Quaternary ammonium compounds, di-C12-18-alkyldimethyl, chlorides

Endpoint summary

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

From February 10, 2004 to March 13, 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Objective of study:

absorption

distribution

excretion

metabolism

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories France, L’Arbresle, France. Caesarean Obtained, Barrier Sustained-Virus Antibody Free (COBS-VAF®).
- Age at study initiation: 7 wk old; for the bile collection group, animals were around 10 wk (males) 12 wk females).
- Weight at study initiation: 229 g males and 159 g females
- Fasting period before study: Overnight
- Housing: 2 or 3 animals/cage in oral groups and singly in dermal and bile collection group
- Diet (e.g. ad libitum): A04 C pelleted diet ad libitum
- Water (e.g. ad libitum): Filtered tap water ad libitum
- Acclimation period: At least 7 d

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22± 2 °C
- Humidity (%): 50±20%
- Air changes (per hr): 12 cycles/h of filtered, non-recycled air
- Photoperiod: 12 h light/ 12 h dark

Route of administration:

other: Oral gavage and dermal

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Amount of vehicle (if gavage): 10 mL/kg



TEST SITE
- Area of exposure: Interscapular/upper back region
- % coverage: 10 % (25 -30 cm2 for 250-300 g rat)


REMOVAL OF TEST SUBSTANCE
- Washing (if done): Washed to remove all traces of test material by wiping with at least 3 cotton swabs dampened with water and diluted normal hand soap solution.
- Time after start of exposure: 6 h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 1.5 mL of dosage form/kg ( Dose: 1.5 mg/kg)

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes

Duration and frequency of treatment / exposure:

6 h

Remarks:

Doses / Concentrations:
Oral: 50 and 200 mg/kg/day;
Dermal: 1.5 and 15 mg/kgbw/day

No. of animals per sex per dose / concentration:

9/sex/dose - Plasma/blood pharmacokinetics (Group 1-5)
5/sex/dose - Excretion balance (Group 6-8)
5/sex/dose bile collection (Group 9)

Control animals:

other: Yes: For the purposes of pre-dose sample analysis, plasma, blood and tissues will be collected from at least one untreated supplementary animal/sex using the above mentioned procedures.

Positive control reference chemical:

Not applicable

Details on study design:

- Rationale for animal assignment (if not random): Random

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled : Blood, plasma, serum, urine, feces, cage washes, bile, skin-application site
- Time and frequency of sampling: Oral groups: 0.5, 1, 2, 4, 8, 24, 48, 72 and 96 h post gavage on Day 1 (Groups 1, 2 and 5)
Dermal group: 3, 6, 7, 8, 10, 16, 24, 48 and 72 h post dermal application (Groups 3 and 4)
Excreta and tissue collection: 0-24, 24-48, 48-72, 96-120, 120-144 and 144-168 h after the radioactive gavage/dermal application (Group 6-8)
Bile collection: 0-3, 3-6, 6-12 and 12-24 h post injection/gavage (Group 9)

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled : urine, faeces, tissues, cage washes, bile
- Method type(s) for identification : Radio- HPLC for urine samples and LSC for biological samples

Statistics:

None

Preliminary studies:

None

Type:

absorption

Results:

Low oral bioavailability (0.93 to 3.16 %); rapidly eliminated with a 48 h period

Type:

distribution

Results:

Radioactive levels generally decreased over time in all tissues

Type:

excretion

Results:

A mean 2.57±2.39 (males) and 1.14±0.69 % (females) of the radioactive dose was recovered over the 24 h period in the bile

Details on absorption:

Single dose: The minimal fraction(from urine data) of the oral dose absorbed systemically was below 3.16 and 1.75 % for males and females respectively.
Repeated dose: The minimal fraction (from urine data) of the oral dose absorbed systemically was below 0.93 and 1.18 % for males and females respectively.

Details on distribution in tissues:

Oral gavage:
50 mg/kg (single dose): The mean radioactivity levels were below quantifiable limits (Group 1) in all tissues except for intestines, kidneys and liver
200 mg/kg (single dose): The mean radioactivity levels were above quantifiable limits (Group 2) in half analysed tissues and organs at 24 h. Specifically high levels were present in adrenals, abdominal fat, eyes, heart, kidneys, liver, lungs, lymph nodes and pancreas.
50 mg/kg (repeated dose): The mean radioactivity levels were below quantifiable limits (Group 1) in all tissues except for intestines, kidneys, liver and mesenteric lymph nodes

Dermal application:
Single application (1.5 mg/kg): Radioactivity levels were below quantifiable limits in all tissues/organs at all time points except for the stripped skin from the application site and intestine (15 mg/kg)
Single application (15 mg/kg): Radioactivity levels were below quantifiable limits in all tissues/organs at all time points except for the stripped skin from the application site, adrenals, heart, kidneys, liver and lungs

Details on excretion:

Following single oral gavage at a nominal dose level of 50 mg/kg to rats, a mean 2.57±2.39 (males) and 1.14±0.69 % (females) of the radioactive dose was recovered over the 24 h period in the bile.

Key result

Toxicokinetic parameters:

other: Oral: Mean plasma and blood radioactivity levels were all below quantifiable limits

Key result

Toxicokinetic parameters:

other: Dermal: Mean plasma and blood radioactivity levels were all below quantifiable limits

Metabolites identified:

no

Details on metabolites:

No metabolites nor parent drug were found in urine samples

Conclusion: Low dermal and oral absorption. The actual minimal fraction of the oral dose absorbed was 0.93 to
3.16%; this was eliminated rapidly, essentially within a 48-hour period.

Conclusions:

Under the study conditions, the test substance was found to have low dermal and oral absorption. The total oral absorption value therefore was roughly in the range around 3-7%, based on urinary (0.93 - 3.16%) and bile (1.8-4.0%) excretion. Further, the study was flawed with respect to the dermal absorption part and did not allow a precise quantification of percutaneous absorption. Nevertheless, based on the results, it can be assumed that dermal absorption is very limited compared to absorption via the oral route.

Executive summary:

A study was conducted to determine the blood and plasma pharmacokinetics, tissue distribution and mass balance of the test substance, 14C-test substance, DDAC (non-radiolabellled: 40.5% active, radilabelled: 98% active) following oral and dermal administrations, according to OECD guideline 417, in compliance with GLP.

Single dermal administration (at 1.5 and 15 mg/kg, as 6 h exposure over 10% of the body surface) and single (at 50 and 200 mg/kg) and repeated (at 50 mg/kg/d) oral gavage administrations of test substance were performed to male and female Sprague-Dawley rats. In addition, the elimination of radioactivity in bile after single oral administration at 50 mg/kg was investigated. Investigations included blood and plasma pharmacokinetics, tissue distribution and mass balance of total radioactivity. The animals were divided into 9 groups; groups 1 to 5 (each of 9 animals/sex) for plasma/blood pharmacokinetics of radioactivity and tissue distribution, groups 6 to 8 (each of 5 animals/sex) principally for excretion balance and group 9 (4 animals/sex) for bile collection. Animals of groups 1 to 4 and 6 and 7 were treated once with the radiolabelled test item. Animals of groups 5 and 8 were treated once per day for 6 d with the unlabelled test item, followed by a single administration of the radiolabelled test material on Day 7. All oral dosages applied 2.2 MBq/kg for radioactive dose-levels, and 3.7 MBq/kg for dermal applications. Dermal dosages were applied on clipped skin approx. 10% of the total body surface area, over the interscapular/ upper back region. The animals wore an Elizabethan collar to prevent ingestion of the test item. At the end of the exposure period, the collar was removed and kept with the swabs for analysis. After 6 h, the treated areas were washed using dampened cotton swabs with diluted hand soap followed by two dry swabs to remove all traces of the test material.

Blood and plasma sampling were performed as follow: (a) Oral group: 0.5, 1, 2, 4, 8, 24, 48, 72 and 96 h (b) Dermal group: 3 and 6 (i.e. during the exposure period), 7, 8, 10, 16, 24, 48 and 72 h. Following the final blood sampling/animal (i.e. at 24, 48 and 72/96 h), each sampled animal was sacrificed by cervical dislocation, under isoflurane anesthesia. The carcass were weighed and the following tissues dissected out and weighed: Adrenals, Gastro intestinal tract (complete), Lymph nodes (mesenteric and mandibular), Brain, Heart, Muscle (right leg adductor), Eyes, Kidneys, Pancreas, Fat (abdominal), Liver, Skin (lower back), Femur (right with marrow), Lungs, Spleen. In addition, for the dermal treated animals, the application site will be dissected out and weighed. Thereafter, the application site and the skin from the lower back will be each stripped completely (using tape) 13 times. No macroscopic examination was performed on the prematurely sacrificed animals or those found dead. Urine and faeces were collected from the groups 6 to 8 animals for the radioactive treatments at the following times: (a) During a period of 24 h before radioactive dosing on Day 1 (Groups 6 and 7), or Day 7 (Group 8) (b) during the periods 0-24, 24-48, 48-72, 72-96, 96-120, 120 -144 and 144-168 h after the radioactive gavage/dermal application. After each collection of faeces, the cages and trays will be carefully rinsed with not more than 20 mL of water (cage wash) (except for last collection; approximately 100 mL will be used).

Following single and/or repeated oral gavage at 50 and 200 mg/kg bw/day, the plasma and blood radioactivity levels were non-quantifiable indicating a low oral bioavailability. The actual minimal fraction of the oral dose absorbed was 0.93 to 3.16%; this was eliminated rapidly, essentially within a 48 -h period. The vast majority of the oral dose was excreted rapidly in the faeces. At the high oral dose-level only, quantifiable levels of radioactivity were found in some central organs at 24 h post- dosing (intestines, liver. kidney) ; otherwise, the vast majority of the dose was confined to the intestines and levels decreased over time. Only 2.57/1.14% (males/females) of the oral dose was eliminated in the bile in a 24-h period. No metabolites or parent drug were found in urine.

Following single dermal application at 1.5 and 15 mg/kg bw, the plasma and blood radioactivity levels were non-quantifiable at all time-points. For the 1.5 mg/kg bw group, around 1% and 50% of the dose was eliminated in the urine and faeces, respectively, mostly within a 48 h period, suggesting that the dermal dose was highly absorbed via the skin. However, as the test site was not protected with an Elizabethan collar during the main part of the collection period (the collar was worn during the exposure period only), this may have been due to the animal licking the test site. This is also supported with the finding that after oral dosing only 1-2.5% was excreted via bile back to intestines, and 2-3 % excreted via urine. At 24 h post- dosing, most of the radioactivity was in the "stripped" skin (dermis and epidermis) application site (6.07 to 21.6% of the dose) and intestines for both dose- levels, though some radioactivity was in the skin adjacent to the application site (most likely from cross- contamination due to grooming) and minor traces were in the eyes and other organs. At 72/168 h, levels in the application site were 1.06 to 2.82% of the radioactive dose, suggesting the skin acted as a drug reservoir. In the stratum corneum of the application site, the levels of radioactivity were of similar magnitude in the different layers at each time point. For all tissues/organs, the radioactivity levels essentially decreased over time. All data showed generally a low inter-animal variability. In addition, there was no evidence of gender differences.

Under the study conditions, the test substance was found to have low dermal and oral absorption. The actual minimal fraction of the oral dose absorbed roughly ranged from 0.93 to 3.16 % (based on urinary excretion) and ((1.8-4.0%) biliary excretion), which was eliminated rapidly, essentially within a 48 h period (Appelqvist, 2006). Further, the study was flawed with respect to the dermal absorption part and did not allow a precise quantification of percutaneous absorption. Nevertheless, based on the results, it can be assumed that dermal absorption is very limited compared to absorption via the oral route.  

Reference 2

Endpoint:

basic toxicokinetics

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

From February 10, 2004 to March 13, 2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

KL2 due to RA

Justification for type of information:

Refer to section 13 of IUCLID for details on the read-across justification. The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Objective of study:

absorption

distribution

excretion

metabolism

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories France, L’Arbresle, France. Caesarean Obtained, Barrier Sustained-Virus Antibody Free (COBS-VAF®).
- Age at study initiation: 7 wk old; for the bile collection group, animals were around 10 wk (males) 12 wk females).
- Weight at study initiation: 229 g males and 159 g females
- Fasting period before study: Overnight
- Housing: 2 or 3 animals/cage in oral groups and singly in dermal and bile collection group
- Diet (e.g. ad libitum): A04 C pelleted diet ad libitum
- Water (e.g. ad libitum): Filtered tap water ad libitum
- Acclimation period: At least 7 d

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22± 2 °C
- Humidity (%): 50±20%
- Air changes (per hr): 12 cycles/h of filtered, non-recycled air
- Photoperiod: 12 h light/ 12 h dark

Route of administration:

other: Oral gavage and dermal

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Amount of vehicle (if gavage): 10 mL/kg



TEST SITE
- Area of exposure: Interscapular/upper back region
- % coverage: 10 % (25 -30 cm2 for 250-300 g rat)


REMOVAL OF TEST SUBSTANCE
- Washing (if done): Washed to remove all traces of test material by wiping with at least 3 cotton swabs dampened with water and diluted normal hand soap solution.
- Time after start of exposure: 6 h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 1.5 mL of dosage form/kg ( Dose: 1.5 mg/kg)

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes

Duration and frequency of treatment / exposure:

6 h

Remarks:

Doses / Concentrations:
Oral: 50 and 200 mg/kg/day;
Dermal: 1.5 and 15 mg/kgbw/day

No. of animals per sex per dose / concentration:

9/sex/dose - Plasma/blood pharmacokinetics (Group 1-5)
5/sex/dose - Excretion balance (Group 6-8)
5/sex/dose bile collection (Group 9)

Control animals:

other: Yes: For the purposes of pre-dose sample analysis, plasma, blood and tissues will be collected from at least one untreated supplementary animal/sex using the above mentioned procedures.

Positive control reference chemical:

Not applicable

Details on study design:

- Rationale for animal assignment (if not random): Random

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled : Blood, plasma, serum, urine, feces, cage washes, bile, skin-application site
- Time and frequency of sampling: Oral groups: 0.5, 1, 2, 4, 8, 24, 48, 72 and 96 h post gavage on Day 1 (Groups 1, 2 and 5)
Dermal group: 3, 6, 7, 8, 10, 16, 24, 48 and 72 h post dermal application (Groups 3 and 4)
Excreta and tissue collection: 0-24, 24-48, 48-72, 96-120, 120-144 and 144-168 h after the radioactive gavage/dermal application (Group 6-8)
Bile collection: 0-3, 3-6, 6-12 and 12-24 h post injection/gavage (Group 9)

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled : urine, faeces, tissues, cage washes, bile
- Method type(s) for identification : Radio- HPLC for urine samples and LSC for biological samples

Statistics:

None

Preliminary studies:

None

Type:

absorption

Results:

Low oral bioavailability (0.93 to 3.16 %); rapidly eliminated with a 48 h period

Type:

distribution

Results:

Radioactive levels generally decreased over time in all tissues

Type:

excretion

Results:

A mean 2.57±2.39 (males) and 1.14±0.69 % (females) of the radioactive dose was recovered over the 24 h period in the bile

Details on absorption:

Single dose: The minimal fraction(from urine data) of the oral dose absorbed systemically was below 3.16 and 1.75 % for males and females respectively.
Repeated dose: The minimal fraction (from urine data) of the oral dose absorbed systemically was below 0.93 and 1.18 % for males and females respectively.

Details on distribution in tissues:

Oral gavage:
50 mg/kg (single dose): The mean radioactivity levels were below quantifiable limits (Group 1) in all tissues except for intestines, kidneys and liver
200 mg/kg (single dose): The mean radioactivity levels were above quantifiable limits (Group 2) in half analysed tissues and organs at 24 h. Specifically high levels were present in adrenals, abdominal fat, eyes, heart, kidneys, liver, lungs, lymph nodes and pancreas.
50 mg/kg (repeated dose): The mean radioactivity levels were below quantifiable limits (Group 1) in all tissues except for intestines, kidneys, liver and mesenteric lymph nodes

Dermal application:
Single application (1.5 mg/kg): Radioactivity levels were below quantifiable limits in all tissues/organs at all time points except for the stripped skin from the application site and intestine (15 mg/kg)
Single application (15 mg/kg): Radioactivity levels were below quantifiable limits in all tissues/organs at all time points except for the stripped skin from the application site, adrenals, heart, kidneys, liver and lungs

Details on excretion:

Following single oral gavage at a nominal dose level of 50 mg/kg to rats, a mean 2.57±2.39 (males) and 1.14±0.69 % (females) of the radioactive dose was recovered over the 24 h period in the bile.

Key result

Toxicokinetic parameters:

other: Oral: Mean plasma and blood radioactivity levels were all below quantifiable limits

Key result

Toxicokinetic parameters:

other: Dermal: Mean plasma and blood radioactivity levels were all below quantifiable limits

Metabolites identified:

no

Details on metabolites:

No metabolites nor parent drug were found in urine samples

Conclusion: Low dermal and oral absorption. The actual minimal fraction of the oral dose absorbed was 0.93 to
3.16%; this was eliminated rapidly, essentially within a 48-hour period.

Conclusions:

Based on the result of the read across study, the test substance was found to have low dermal and oral absorption. The total oral absorption value therefore was roughly in the range around 3-7%, based on urinary (0.93 - 3.16%) and bile (1.8-4.0%) excretion. Further, the study was flawed with respect to the dermal absorption part and did not allow a precise quantification of percutaneous absorption. Nevertheless, based on the results, it can be assumed that dermal absorption is very limited compared to absorption via the oral route.

Executive summary:

A study was conducted to determine the blood and plasma pharmacokinetics, tissue distribution and mass balance of the read across substance, 14C-read across substance, DDAC (non-radiolabellled: 40.5% active, radilabelled: 98% active) following oral and dermal administrations, according to OECD guideline 417, in compliance with GLP.

Single dermal administration (at 1.5 and 15 mg/kg, as 6 h exposure over 10% of the body surface) and single (at 50 and 200 mg/kg) and repeated (at 50 mg/kg/d) oral gavage administrations of read across substance were performed to male and female Sprague-Dawley rats. In addition, the elimination of radioactivity in bile after single oral administration at 50 mg/kg was investigated. Investigations included blood and plasma pharmacokinetics, tissue distribution and mass balance of total radioactivity. The animals were divided into 9 groups; groups 1 to 5 (each of 9 animals/sex) for plasma/blood pharmacokinetics of radioactivity and tissue distribution, groups 6 to 8 (each of 5 animals/sex) principally for excretion balance and group 9 (4 animals/sex) for bile collection. Animals of groups 1 to 4 and 6 and 7 were treated once with the radiolabelled test item. Animals of groups 5 and 8 were treated once per day for 6 d with the unlabelled test item, followed by a single administration of the radiolabelled test material on Day 7. All oral dosages applied 2.2 MBq/kg for radioactive dose-levels, and 3.7 MBq/kg for dermal applications. Dermal dosages were applied on clipped skin approx. 10% of the total body surface area, over the interscapular/ upper back region. The animals wore an Elizabethan collar to prevent ingestion of the test item. At the end of the exposure period, the collar was removed and kept with the swabs for analysis. After 6 h, the treated areas were washed using dampened cotton swabs with diluted hand soap followed by two dry swabs to remove all traces of the test material.

Blood and plasma sampling were performed as follow: (a) Oral group: 0.5, 1, 2, 4, 8, 24, 48, 72 and 96 h (b) Dermal group: 3 and 6 (i.e. during the exposure period), 7, 8, 10, 16, 24, 48 and 72 h. Following the final blood sampling/animal (i.e. at 24, 48 and 72/96 h), each sampled animal was sacrificed by cervical dislocation, under isoflurane anesthesia. The carcass were weighed and the following tissues dissected out and weighed: Adrenals, Gastro intestinal tract (complete), Lymph nodes (mesenteric and mandibular), Brain, Heart, Muscle (right leg adductor), Eyes, Kidneys, Pancreas, Fat (abdominal), Liver, Skin (lower back), Femur (right with marrow), Lungs, Spleen. In addition, for the dermal treated animals, the application site will be dissected out and weighed. Thereafter, the application site and the skin from the lower back will be each stripped completely (using tape) 13 times. No macroscopic examination was performed on the prematurely sacrificed animals or those found dead. Urine and faeces were collected from the groups 6 to 8 animals for the radioactive treatments at the following times: (a) During a period of 24 h before radioactive dosing on Day 1 (Groups 6 and 7), or Day 7 (Group 8) (b) during the periods 0-24, 24-48, 48-72, 72-96, 96-120, 120 -144 and 144-168 h after the radioactive gavage/dermal application. After each collection of faeces, the cages and trays will be carefully rinsed with not more than 20 mL of water (cage wash) (except for last collection; approximately 100 mL will be used).

Following single and/or repeated oral gavage at 50 and 200 mg/kg bw/day, the plasma and blood radioactivity levels were non-quantifiable indicating a low oral bioavailability. The actual minimal fraction of the oral dose absorbed was 0.93 to 3.16%; this was eliminated rapidly, essentially within a 48 -h period. The vast majority of the oral dose was excreted rapidly in the faeces. At the high oral dose-level only, quantifiable levels of radioactivity were found in some central organs at 24 h post- dosing (intestines, liver. kidney) ; otherwise, the vast majority of the dose was confined to the intestines and levels decreased over time. Only 2.57/1.14% (males/females) of the oral dose was eliminated in the bile in a 24-h period. No metabolites or parent drug were found in urine.

Following single dermal application at 1.5 and 15 mg/kg bw, the plasma and blood radioactivity levels were non-quantifiable at all time-points. For the 1.5 mg/kg bw group, around 1% and 50% of the dose was eliminated in the urine and faeces, respectively, mostly within a 48 h period, suggesting that the dermal dose was highly absorbed via the skin. However, as the test site was not protected with an Elizabethan collar during the main part of the collection period (the collar was worn during the exposure period only), this may have been due to the animal licking the test site. This is also supported with the finding that after oral dosing only 1-2.5% was excreted via bile back to intestines, and 2-3 % excreted via urine. At 24 h post- dosing, most of the radioactivity was in the "stripped" skin (dermis and epidermis) application site (6.07 to 21.6% of the dose) and intestines for both dose- levels, though some radioactivity was in the skin adjacent to the application site (most likely from cross- contamination due to grooming) and minor traces were in the eyes and other organs. At 72/168 h, levels in the application site were 1.06 to 2.82% of the radioactive dose, suggesting the skin acted as a drug reservoir. In the stratum corneum of the application site, the levels of radioactivity were of similar magnitude in the different layers at each time point. For all tissues/organs, the radioactivity levels essentially decreased over time. All data showed generally a low inter-animal variability. In addition, there was no evidence of gender differences.

Under the study conditions, the read across substance was found to have low dermal and oral absorption. The actual minimal fraction of the oral absorbed dose roughly ranged from 0.93 to 3.16 % (based on urinary excretion) and ((1.8-4.0%) biliary excretion), which was eliminated rapidly, essentially within a 48 h period (Appelqvist, 2006). Further, the study was flawed with respect to the dermal absorption part and did not allow a precise quantification of percutaneous absorption. Nevertheless, based on the results, it can be assumed that dermal absorption is very limited compared to absorption via the oral route.  

Based on the result of the read across study,similar toxicokinetic profile can be expected for the test substance.

Reference 3

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Objective of study:

absorption

distribution

excretion

Principles of method if other than guideline:

The test material is administered by an oral/dermal route. The absorption, distribution and excretion of the test material were investigated.

GLP compliance:

no

Radiolabelling:

yes

Species:

rat

Strain:

other: Iva:SIV 50

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Individual metabolism cages: yes
- Weight at study initiation: 200- 300 g

Route of administration:

other: dermal & oral intubation

Vehicle:

other: Isopropanol/H20 2:3.

Details on exposure:

TEST SITE
- Area of exposure: Trunk
- % coverage: 2 cm2
- Type of wrap if used: Poro Plast ophthalmologic plaster provided with an elevated plastic window was placed in position over the application site with adhesive tape during the exposure time of at least 72 h


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 or 200 µL

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes

Duration and frequency of treatment / exposure:

72 h

Remarks:

Doses / Concentrations:
Dermal: 100 and 200 µL test solution
Oral: 200 µL test solution
Test solution contains 2500 ppm of test material in isopropanol/H20, 2:3.

No. of animals per sex per dose / concentration:

4 animals -Dermal
4 animals- Oral

Control animals:

no

Positive control reference chemical:

Not applicable

Details on study design:

No data

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled : urine, faeces, liver, kidney, spleen, heart, lung and muscle

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled : urine
- Method type(s) for identification: Scintillation counting, and Radio TLC/autoradiogram

Statistics:

No data

Preliminary studies:

No data

Type:

absorption

Results:

Very poor

Type:

distribution

Results:

Very poor

Type:

excretion

Results:

Total urinary excretion amounted to only 1.3 and 1.4% o f the administered dose after dermal and oral treatment respectively

Details on absorption:

Dermal and gastrointestinal absorption are very poor

Details on distribution in tissues:

Dermal application (mean): Liver and kidney 0.02 and 0.01 % of the dose respectively
Oral (mean): Liver and kidney= 0.04 and 0.01 % respectively

Details on excretion:

Total urinary excretion amounted to only 1.3 and 1.4 % o f the administered dose after dermal and oral treatment respectively

Metabolites identified:

no

Details on metabolites:

Approximately 20% of the excreted radioactivity were eliminated as the parent compound whereas the remaining obviously did undergo metabolic alteration most probably by oxidation and conjugation reactions. Approximately 4% of the urinary [3H] activities were extractable after treatment with glucuronidase/sulfatase, another 20% after strong hydrolytic treatment, most probably resulting in the cleavage of other conjugates. No further attempts were made to identify the metabolites.

Results:
Dermal and gastrointestinal absorption are very poor. Total urinary excretion amounted to only 1.3% and 1.4% of the
administered dose after dermal and oral treatment respectively. The amount of [3H] activity measured in the
organs was also similar in both groups. No target organ was found.

Urinary Metabolites: 
The consecutive extractions of the urine of orally dosed animals before and after enzymatic and hydrolytic cleavage
revealed that approximately 20% of the excreted radioactivity were eliminated as the parent compound whereas
the remaining obviously did undergo metabolic alteration most probably by oxidation and conjugation reactions.
Approximately 4% of the urinary [3H] activity were extractable after treatment with glucuronidase/sulfatase,
another 20% after strong hydrolytic treatment, most probably resulting in the cleavage of other conjugates. No further
attempts were made to identify the metabolites.

Conclusions:

Under the study conditions, the total absorption, excretion of radioactivity in the urine and the amounts found in the tissues were very low after the administration of test substance by the dermal as well as the oral route in rats.

Executive summary:

A study was conducted to determine the absorption, distribution and excretion patterns following the administration of test substance, DDAI (radiolabelled - purity not specified) by the dermal and the oral route in rats. Dermal and gastrointestinal absorption were very poor. Total urinary excretion amounted to only 1.3 and 1.4% of the administered dose after dermal and oral treatment respectively. The amount of [³H] activity measured in the organs was also similar in both groups. No target organ was found. The consecutive extractions of the urine of orally dosed animals before and after enzymatic and hydrolytic cleavage revealed that approximately 20% of the excreted radioactivity were eliminated as the parent compound whereas the remaining obviously did undergo metabolic alteration most probably by oxidation and conjugation reactions.  Approximately 4% o f the urinary [³H] activity were extractable after treatment with glucuronidase/sulfatase, another 20 % after strong hydrolytic treatment, most probably resulting in the cleavage of other conjugates. No further attempts were made to identify the metabolites. These findings indicate that the test substance does not readily penetrate cell membranes and that it was very stable and did not undergo considerable degradation on the skin or in the stomach. The studies on the radioactivity extracted from urine revealed that part of the metabolism most probably proceeded by oxidation and conjugation reactions analogous to the degradation of the fatty acids by β-oxidation. Under the study conditions, the total absorption, excretion of radioactivity in the urine and the amounts found in the tissues were very low after the administration of test substance by the dermal as well as the oral route in rats (Bosshard & Schlatter, 1982).

Reference 4

Endpoint:

basic toxicokinetics in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Refer to section 13 of IUCLID for details on the read-across justification. The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Objective of study:

absorption

distribution

excretion

Principles of method if other than guideline:

The test material is administered by an oral/dermal route. The absorption, distribution and excretion of the test material were investigated.

GLP compliance:

no

Radiolabelling:

yes

Species:

rat

Strain:

other: Iva:SIV 50

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Individual metabolism cages: yes
- Weight at study initiation: 200- 300 g

Route of administration:

other: dermal & oral intubation

Vehicle:

other: Isopropanol/H20 2:3.

Details on exposure:

TEST SITE
- Area of exposure: Trunk
- % coverage: 2 cm2
- Type of wrap if used: Poro Plast ophthalmologic plaster provided with an elevated plastic window was placed in position over the application site with adhesive tape during the exposure time of at least 72 h


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 or 200 µL

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes

Duration and frequency of treatment / exposure:

72 h

Remarks:

Doses / Concentrations:
Dermal: 100 and 200 µL test solution
Oral: 200 µL test solution
Test solution contains 2500 ppm of test material in isopropanol/H20, 2:3.

No. of animals per sex per dose / concentration:

4 animals -Dermal
4 animals- Oral

Control animals:

no

Positive control reference chemical:

Not applicable

Details on study design:

No data

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled : urine, faeces, liver, kidney, spleen, heart, lung and muscle

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled : urine
- Method type(s) for identification: Scintillation counting, and Radio TLC/autoradiogram

Statistics:

No data

Preliminary studies:

No data

Type:

absorption

Results:

Very poor

Type:

distribution

Results:

Very poor

Type:

excretion

Results:

Total urinary excretion amounted to only 1.3 and 1.4% o f the administered dose after dermal and oral treatment respectively

Details on absorption:

Dermal and gastrointestinal absorption are very poor

Details on distribution in tissues:

Dermal application (mean): Liver and kidney 0.02 and 0.01 % of the dose respectively
Oral (mean): Liver and kidney= 0.04 and 0.01 % respectively

Details on excretion:

Total urinary excretion amounted to only 1.3 and 1.4 % o f the administered dose after dermal and oral treatment respectively

Metabolites identified:

no

Details on metabolites:

Approximately 20% of the excreted radioactivity were eliminated as the parent compound whereas the remaining obviously did undergo metabolic alteration most probably by oxidation and conjugation reactions. Approximately 4% of the urinary [3H] activities were extractable after treatment with glucuronidase/sulfatase, another 20% after strong hydrolytic treatment, most probably resulting in the cleavage of other conjugates. No further attempts were made to identify the metabolites.

Results:
Dermal and gastrointestinal absorption are very poor. Total urinary excretion amounted to only 1.3% and 1.4% of the
administered dose after dermal and oral treatment respectively. The amount of [3H] activity measured in the
organs was also similar in both groups. No target organ was found.

Urinary Metabolites: 
The consecutive extractions of the urine of orally dosed animals before and after enzymatic and hydrolytic cleavage
revealed that approximately 20% of the excreted radioactivity were eliminated as the parent compound whereas
the remaining obviously did undergo metabolic alteration most probably by oxidation and conjugation reactions.
Approximately 4% of the urinary [3H] activity were extractable after treatment with glucuronidase/sulfatase,
another 20% after strong hydrolytic treatment, most probably resulting in the cleavage of other conjugates. No further
attempts were made to identify the metabolites.

Conclusions:

Based on the results of the read across study, the total absorption, excretion of radioactivity in the urine and the amounts found in the tissues are considered very low after the administration of test substance by the dermal as well as the oral route in rats.

Executive summary:

A study was conducted to determine the absorption, distribution and excretion patterns following the administration of read across substance, DDAI (radiolabelled - purity not specified) by the dermal and the oral route in rats. Dermal and gastrointestinal absorption were very poor. Total urinary excretion amounted to only 1.3 and 1.4% of the administered dose after dermal and oral treatment respectively. The amount of [³H] activity measured in the organs was also similar in both groups. No target organ was found. The consecutive extractions of the urine of orally dosed animals before and after enzymatic and hydrolytic cleavage revealed that approximately 20% of the excreted radioactivity were eliminated as the parent compound whereas the remaining obviously did undergo metabolic alteration most probably by oxidation and conjugation reactions. Approximately 4% o f the urinary [³H] activity were extractable after treatment with glucuronidase/sulfatase, another 20 % after strong hydrolytic treatment, most probably resulting in the cleavage of other conjugates. No further attempts were made to identify the metabolites. These findings indicate that the read across substance does not readily penetrate cell membranes and that it was very stable and did not undergo considerable degradation on the skin or in the stomach. The studies on the radioactivity extracted from urine revealed that part of the metabolism most probably proceeded by oxidation and conjugation reactions analogous to the degradation of the fatty acids by β-oxidation (Bosshard & Schlatter, 1982). Based on the results of the read across study, similar toxicokinetic profile is expected for the test substance.

Reference 5

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not reported

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Remarks:

Review article, no primary reference.

Objective of study:

absorption

distribution

excretion

metabolism

Principles of method if other than guideline:

Study has been performed to determine absorption, distribution, metabolism and excretion following administration of 14C- labelled test material in rats.

GLP compliance:

not specified

Radiolabelling:

yes

Species:

rat

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

No data

Route of administration:

other: gavage, repeat: diet

Vehicle:

not specified

Details on exposure:

No data

Duration and frequency of treatment / exposure:

Acute and 14 d

Remarks:

Doses / Concentrations:
Single: 5 mg or 50 mg DDAC,
Repeat: 34 ppm DDAC in diet for 14 d

No. of animals per sex per dose / concentration:

3/sex/dose

Control animals:

no

Positive control reference chemical:

None

Details on study design:

No data

Details on dosing and sampling:

No data

Statistics:

No data

Preliminary studies:

The preliminary experiment collected data on the amount of 14C eliminated in the expired air following acute oral administration of 14C-DDAC. The results showed that little or no radioactivity (0.041- 0.054% of dose) was excreted as 14CO2, during the 24 h following oral administration of14C -DDAC. This indicates that the 14C radiolabel was in a stable portion of the DDAC molecule.

Type:

absorption

Results:

Test material is not well absorbed from the gastro-intestinal tract, and only a negligible amount (0.003-0.675 %) remained in the body after 7 d.

Type:

distribution

Results:

Only a negligible amount (0.003-0.675 %) remained in the body after 7 d.

Type:

metabolism

Results:

The four major metabolites found in this study were more polar and presumed to be less toxic than the parent compound, although their chemical structures were not definitively identified.

Type:

excretion

Results:

No radioactivity was excreted as 14CO2 indicating that the label was in a stable portion of the molecule. In the faeces 89-99% of the radioactive material was recovered, and less than 2.5 % was found in the urine.

Details on absorption:

As the test material is highly ionic, it is not expected to be well absorbed from the gastrointestinal tract after oral administration. Test material is not well absorbed from the gastro-intestinal tract, and only a negligible amount (0.003-0.675 %) remained in the body after 7 d.

Details on distribution in tissues:

Only a negligible amount (0.003-0.675 %) remained in the body after 7 d.

Details on excretion:

No radioactivity was excreted as 14CO2 indicating that the label was in a stable portion of the molecule. In the faeces 89-99% of the radioactive material was recovered, and less than 2.5 % was found in the urine.

Metabolites identified:

no

Details on metabolites:

The four major metabolites found in this study were more polar and presumed to be less toxic than the parent compound, although their chemical structures were not definitively identified.

None

Conclusions:

Under the study conditions, the test substance had low absorption (ca. 2.5%) after oral administration, metabolized via hydroxylation/oxidation to form polar metabolites, excreted in the urine and faeces and a negligible amount (0.003-0.675 %) retained in the body after 1 week.

Executive summary:

One preliminary and three large scale pharmacokinetic experiments were conducted to determine the absorption, distribution, metabolism and excretion patterns following the administration of 14-C radiolabeled test substance, DDAC (purity not specified). The preliminary experiment collected data on the amount of 14C eliminated in the expired air following acute oral administration of 14C-DDAC. The results showed that little or no radioactivity (0.041- 0.054% of dose) was excreted as14CO2, during the 24 h following oral administration of 14C -DDAC. This indicated that the 14C radiolabel was in a stable portion of the DDAC molecule. Three large-scale pharmacokinetic studies were performed to determine absorption, distribution, metabolism and excretion following administration of 5 mg or 50 mg 14C- labelled DDAC, using 5 male and 5 female rats each. Animals were dosed with either 5 mg 14C-labelled test substance (low dose groups), or with 50 mg/kg bw (high dose group). Rats in the third experiment were repeatedly administered low oral dose of 5 mg/kg 14-C labelled test substance. For all groups urine and faeces were collected for analysis and after 7days, rats were euthanised for analysis of selected tissue and organs for radioactivity. From this study, the test substance was found to be not well absorbed from the gastro-intestinal tract, and only a negligible amount (0.003-0.675%) remained in the body after 7 days. No radioactivity was excreted as 14CO2 indicating that the label was in a stable portion of the molecule. In the faeces 89-99% of the radioactive material was recovered, and less than 2.5% was found in the urine. A further study to evaluate the metabolic profile of the labelled 14C-residues in the faeces indicated a similar pattern of excretion between the sexes, although a dose -dependent metabolism was observed in females: more parent compound was metabolized in the single low oral dose than in the single high oral dose. The metabolic process for the test substance in the rat was found to involve oxidation of the decyl side-chain to a variety of oxidative products. Evidence seems to favour initial hydroxylation of the carbon next to the terminal carbon, followed by formation of a hydroxyketone. The four major metabolites found in this study were more polar and presumed to be less toxic than the parent compound, although their chemical structures were not definitively identified. Under the study conditions, the test substance had low absorption (ca. 2.5%) after oral administration, metabolized via hydroxylation/oxidation to form polar metabolites, excreted in the urine and faeces and a negligible amount (0.003-0.675 %) retained in the body after 1 week (Henderson, 1992).

Reference 6

Endpoint:

basic toxicokinetics in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

Not reported

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Remarks:

Review article, no primary reference.

Justification for type of information:

Refer to section 13 of IUCLID for details on the read-across justification. The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

read-across source

Objective of study:

absorption

distribution

excretion

metabolism

Principles of method if other than guideline:

Study has been performed to determine absorption, distribution, metabolism and excretion following administration of 14C- labelled test material in rats.

GLP compliance:

not specified

Radiolabelling:

yes

Species:

rat

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

No data

Route of administration:

other: gavage, repeat: diet

Vehicle:

not specified

Details on exposure:

No data

Duration and frequency of treatment / exposure:

Acute and 14 d

Remarks:

Doses / Concentrations:
Single: 5 mg or 50 mg DDAC,
Repeat: 34 ppm DDAC in diet for 14 d

No. of animals per sex per dose / concentration:

3/sex/dose

Control animals:

no

Positive control reference chemical:

None

Details on study design:

No data

Details on dosing and sampling:

No data

Statistics:

No data

Preliminary studies:

The preliminary experiment collected data on the amount of 14C eliminated in the expired air following acute oral administration of 14C-DDAC. The results showed that little or no radioactivity (0.041- 0.054% of dose) was excreted as 14CO2, during the 24 h following oral administration of14C -DDAC. This indicates that the 14C radiolabel was in a stable portion of the DDAC molecule.

Type:

absorption

Results:

Test material is not well absorbed from the gastro-intestinal tract, and only a negligible amount (0.003-0.675 %) remained in the body after 7 d.

Type:

distribution

Results:

Only a negligible amount (0.003-0.675 %) remained in the body after 7 d.

Type:

metabolism

Results:

The four major metabolites found in this study were more polar and presumed to be less toxic than the parent compound, although their chemical structures were not definitively identified.

Type:

excretion

Results:

No radioactivity was excreted as 14CO2 indicating that the label was in a stable portion of the molecule. In the faeces 89-99% of the radioactive material was recovered, and less than 2.5 % was found in the urine.

Details on absorption:

As the test material is highly ionic, it is not expected to be well absorbed from the gastrointestinal tract after oral administration. Test material is not well absorbed from the gastro-intestinal tract, and only a negligible amount (0.003-0.675 %) remained in the body after 7 d.

Details on distribution in tissues:

Only a negligible amount (0.003-0.675 %) remained in the body after 7 d.

Details on excretion:

No radioactivity was excreted as 14CO2 indicating that the label was in a stable portion of the molecule. In the faeces 89-99% of the radioactive material was recovered, and less than 2.5 % was found in the urine.

Metabolites identified:

no

Details on metabolites:

The four major metabolites found in this study were more polar and presumed to be less toxic than the parent compound, although their chemical structures were not definitively identified.

None

Conclusions:

Based on the results of read across study, the read across substance had low absorption (ca. 2.5%) after oral administration, metabolized via hydroxylation/oxidation to form polar metabolites, excreted in the urine and faeces and a negligible amount (0.003-0.675 %) retained in the body after 1 week (Henderson, 1992).

Executive summary:

One preliminary and three large scale pharmacokinetic experiments were conducted to determine the absorption, distribution, metabolism and excretion patterns following the administration of 14-C radiolabeled read across substance, DDAC (purity not specified). The preliminary experiment collected data on the amount of 14C eliminated in the expired air following acute oral administration of 14C-DDAC. The results showed that little or no radioactivity (0.041- 0.054% of dose) was excreted as14CO2, during the 24 h following oral administration of 14C -DDAC. This indicated that the 14C radiolabel was in a stable portion of the DDAC molecule. Three large-scale pharmacokinetic studies were performed to determine absorption, distribution, metabolism and excretion following administration of 5 mg or 50 mg 14C- labelled DDAC, using 5 male and 5 female rats each. Animals were dosed with either 5 mg 14C-labelled read across substance (low dose groups), or with 50 mg/kg bw (high dose group). Rats in the third experiment were repeatedly administered low oral dose of 5 mg/kg 14-C labelled read across substance. For all groups urine and faeces were collected for analysis and after 7days, rats were euthanised for analysis of selected tissue and organs for radioactivity. From this study, the read across substance was found to be not well absorbed from the gastro-intestinal tract, and only a negligible amount (0.003-0.675%) remained in the body after 7 days. No radioactivity was excreted as 14CO2 indicating that the label was in a stable portion of the molecule. In the faeces 89-99% of the radioactive material was recovered, and less than 2.5% was found in the urine. A further study to evaluate the metabolic profile of the labelled 14C-residues in the faeces indicated a similar pattern of excretion between the sexes, although a dose -dependent metabolism was observed in females: more parent compound was metabolized in the single low oral dose than in the single high oral dose. The metabolic process for the read across substance in the rat was found to involve oxidation of the decyl side-chain to a variety of oxidative products. Evidence seems to favour initial hydroxylation of the carbon next to the terminal carbon, followed by formation of a hydroxyketone. The four major metabolites found in this study were more polar and presumed to be less toxic than the parent compound, although their chemical structures were not definitively identified. Under the study conditions, the read across substance had low absorption (ca. 2.5%) after oral administration, metabolized via hydroxylation/oxidation to form polar metabolites, excreted in the urine and faeces and a negligible amount (0.003-0.675 %) retained in the body after 1 week (Henderson, 1992). Based on the results of read across study, the test substance is expected to have similar toxicokinetic profile.

Description of key information

Based on the available weight of evidence and the cationic nature, the test substance, C12-18 DAQ, is expected to have a low absorption potential followed by excretion primarily via feces. Based on QSAR predictions and data on read across substance, it is likely to undergo aliphatic hydroxylation as the first metabolic reaction. Further, based on its ionic nature, molecular weight and key physico-chemical properties it is likely to have no or very bioaccumulation potential. 

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

10

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

50

Additional information

ABSORPTION:  

Oral absorption  

Based on physicochemical properties:  

According to REACH guidance document R7.C (May 2014), oral absorption is maximal for substances with molecular weight (MW) below 500. Water-soluble substances will readily dissolve into the gastrointestinal fluids; however, absorption of hydrophilic substances via passive diffusion may be limited by the rate at which the substance partitions out of the gastrointestinal fluid. Further, absorption by passive diffusion is higher at moderate log Kow values (between -1 and 4). If signs of systemic toxicity are seen after oral administration (other than those indicative of discomfort or lack of palatability of the test substance), then absorption has occurred. 

The test substance, C12-18 DAQ is a di-alkyl dimethyl ammonium chloride, which is a cationic surfactant and a UVCB with majorly C12-18 alkyl chain lengths. It molecular weight ranges from 362.09 to 586.5 g/mol. The purified form of the substance is a solid lumpy paste. It has a moderate low solubility of 2.3 mg/L at 25°C (based on CMC) and a low log Kow of 4.8 value, which was determined using slow stirring method. 

Based on the R7.C indicative criteria, together with the fact that the test substance is cationic with a strong adherence potential to the negatively charged surfaces of the membranes, suggests that the it is not expected to easily pass biological membranes.

 

Based on experimental data on read across substances:  

 

A study was conducted to determine the absorption, distribution and excretion patterns following the administration of test substance, DDAI (radiolabelled - purity not specified) the oral route in rats. The gastrointestinal absorption were very poor. Total urinary excretion amounted to only 1.4% of the administered dose. The amount of [3H] activity measured in the organs was low and no target organ was found.The consecutive extractions of the urine of orally dosed animals before and after enzymatic and hydrolytic cleavage revealed that approximately 20% of the excreted radioactivity were eliminated as the parent compound whereas the remaining obviously did undergo metabolic alteration most probably by oxidation and conjugation reactions.  Approximately 4% of the urinary [3H] activity were extractable after treatment with glucuronidase/sulfatase, another 20 % after strong hydrolytic treatment, most probably resulting in the cleavage of other conjugates. No further attempts were made to identify the metabolites. These findings indicate that the test substance does not readily penetrate cell membranes and that it was very stable and did not undergo considerable degradation in the stomach.The studies on the radioactivity extracted from urine revealed that part of the metabolism most probably proceeded by oxidation and conjugation reactions analogous to the degradation of the fatty acids by β-oxidation. Under the study conditions, the total absorption, excretion of radioactivity in the urine and the amounts found in the tissues were very low after the administration of test substance by the oral route in rats (Bosshard & Schlatter, 1982).

 

One preliminary and three large scale pharmacokinetic experiments were conducted to determine the absorption, distribution, metabolism and excretion patterns following the administration of 14-C radiolabeled read across substance, DDAC (purity not specified). The preliminary experiment collected data on the amount of 14C eliminated in the expired air following acute oral administration of 14C-DDAC. The results showed that little or no radioactivity (0.041- 0.054% of dose) was excreted as14CO2, during the 24 h following oral administration of 14C -DDAC. This indicated that the 14C radiolabel was in a stable portion of the DDAC molecule. Three large-scale pharmacokinetic studies were performed to determine absorption, distribution, metabolism and excretion following administration of 5 mg or 50 mg 14C- labelled DDAC, using 5 male and 5 female rats each. Animals were dosed with either 5 mg 14C-labelled read across substance (low dose groups), or with 50 mg/kg bw (high dose group). Rats in the third experiment were repeatedly administered low oral dose of 5 mg/kg 14-C labelled read across substance. For all groups urine and faeces were collected for analysis and after 7days, rats were euthanised for analysis of selected tissue and organs for radioactivity. From this study, the read across substance was found to be not well absorbed from the gastro-intestinal tract, and only a negligible amount (0.003-0.675%) remained in the body after 7 days. No radioactivity was excreted as 14CO2 indicating that the label was in a stable portion of the molecule. In the faeces 89-99% of the radioactive material was recovered, and less than 2.5% was found in the urine. Under the study conditions, the read across substance had low absorption (ca. 2.5%) after oral administration which was primarily excreted in the urine and faeces. Only a negligible amount (0.003-0.675 %) retained in the body after 1 week (Henderson, 1992).

A study was conducted to determine the basic toxicokinetics of the read across substance, DDAC (non-radiolabellled: 40.5% active,radiolabelled: 98% active), according to OECD Guideline 417, in compliance with GLP. In this study, Sprague-Dawley rats were treated with single and repeated oral doses (50 or 200 mg/kg bw) as well as a single dermal dose (1.5 or 15 mg/kg bw for 6 h) of the radiolabelled read across substance. Following single and/or repeated oral doses, the plasma, blood and organ radioactivity levels were essentially non-quantifiable, indicating a low oral bioavailability.The actual minimal fraction of the oral dose absorbed was 0.93 to 3.16%; this was eliminated rapidly, essentially within a 48 -h period. The vast majority of the oral dose was excreted rapidly in the faeces.At the high oral dose level only, quantifiable levels of radioactivity were found in some central organs at 8 h post-dosing(intestines, liver. kidney);otherwise, the vast majority of the dose was confined to the intestines, where their levels decreased over time. Only2.57/1.14% (males/females) and 3.16/1.75% (males/females) of the oral dose was eliminated in the bile and urine in a 24-h period. This indicates that, after intestinal absorption, excretion via bile and urine are of similar magnitude. The total oral absorption value therefore was roughly in the range around 3-7%, based on urinary (0.93 - 3.16%) and bile (1.8-4.0%) excretion. The total oral absorption value therefore was roughly in the range around 3-7%, based on urinary (0.93 - 3.16%) and bile (1.8-4.0%) excretion.Under the conditions of the study and following oral administration the read across substance was found to have limited absorption (ca. 3-7%), low distribution (limited to low amounts inintestines, liver. Kidney)and majorly excreted via faeces (ca. >80%) (Appelqvist, 2006).

Further, the DDAC assessment report for Product Type 8 conducted under Directive 98/8/EC (evaluating Competent Authority: Italy, June 2015, attached in Section 13 of the IUCLID dataset), which reported the above study stated that“Based on the urinary excretion (3-4%), biliary excretion values (2.6%), the absence of residues in the carcass, and 85-90% recovery of radioactivity in faeces as unabsorbed material the actual absorbed fraction is approximately 10% of the orally administered dose, at non-corrosive concentrations.”An additional toxicokinetics study with DDAC was reported in rats, where the majority (>90%) of orally administered DDAC was excreted, very likely unabsorbed, via the faeces. Based on data on urine excretion (ca. 3%) and tissue residues (<1%), and on the 90% recovery of radioactivity obtained in the available toxicokinetic study, it was expected that the oral absorption was limited to ca. 10% at non corrosive concentration).

Conclusion:Overall, based on the available weight of evidence information, the test substance can be expected to overall have low absorption potential through the oral route. Therefore, in line with the biocide assessment report and as a conservative approach a maximum oral absorption value of 10% can be considered for risk assessment.   

Dermal absorption  

Based on physicochemical properties:  

According to REACH guidance document R7.C (ECHA, 2017), dermal absorption is maximal for substances having MW below 100 together with log Kow values ranging between 2 and 3 and water solubility in the range of 100-10,000 mg/L. Substances with MW above 500 are considered to be too large to penetrate skin. Further, dermal uptake is likely to be low for substances with log P values <0 or <-1, as they are not likely to be sufficiently lipophilic to cross the stratum corneum (SC). Similarly, substances with water solubility below 1 mg/L are also likely to have low dermal uptake, as the substances must be sufficiently soluble in water to partition from the SC into the epidermis. 

The test substance is a solid paste, with an MW exceeding 100 g/mol, low water solubility and an estimated log Kow above 3.This together with the fact that the test substance is cationic with a strong adherence potential to the negatively charged surfaces, suggests that the test substance at non-corrosive concentrations is likely to have a low penetration potential through the skin. 

At higher corrosive concentrations although there is a likelihood of exposure to the test substance due to disruption of the barrier properties of the skin, the likelihood of occurrence of these cases is expected to be minimal due to the required risk management measures and self-limiting nature of the hazard. Therefore, this scenario has not been considered further for toxicokinetic assessment.

Based on (Q)SAR prediction:  

The two well-known parameters often used to characterise percutaneous penetration potential of substances are the dermal permeability coefficient (Kp[1]) and maximum flux (Jmax). Kp reflects the speed with which a chemical penetrates across SC and Jmax represents the rate of penetration at steady state of an amount of permeant after application over a given area of SC. Out of the two, although Kp is more widely used in percutaneous absorption studies as a measure of solute penetration into the skin. However, it is not a practical parameter because for a given solute, the value of Kp depends on the vehicle used to deliver the solute. Hence, Jmax i.e., the flux attained at the solubility of the solute in the vehicle is considered as the more useful parameter to assess dermal penetration potential as it is vehicle independent (Robert and Walters, 2007).  

In the absence of experimental data, Jmax can be calculated by multiplying the estimated water solubility (using WATERNT v.1.02) with the Kp values from DERMWIN v2.02 application of EPI Suite v4.11. The calculated Jmax values for the different carbon chains of the UVCB substance was determined to be range between 1.13E-6 to 3.06E-03μg/cm2/h, leading to a weighted average value of 1.18E-4μg/cm2/h. As per Kroeset al.,2004 and Shenet al. 2014, the default dermal absorption for substances with Jmax ≤0.1 μg/cm2/h can be considered to be less than 10%. Based on this, the test substance can be predicted to have low absorption potential through the dermal route.  

Based on experimental data on read across substances:  

A study was conducted to determine the absorption, distribution and excretion patterns following the administration of test substance, DDAI (radiolabelled - purity not specified) by the dermal route in rats. Dermal absorption were very poor. Total urinary excretion amounted to only 1.3% of the administered dose. The amount of [3H] activity measured in the organs was low and no target organ was found. Under the study conditions, the total absorption, excretion of radioactivity in the urine and the amounts found in the tissues were very low after the administration of test substance by the dermal route in rats (Bosshard & Schlatter, 1982).

Further, following a single dermal application of the read across substance, C12-16 ADBAC in the Appelqvist (2006) study, the plasma and blood radioactivity levels were non-quantifiable at all time-points. For the 1.5 mg/kg bw group, around 1 and 53% of the dose was eliminated in the urine and faeces, respectively, mostly within a 48-h period, suggesting that the dermal dose was highly absorbed via the skin. However, this apparent high absorption via the skin may have been due to the animal licking the test site. This was also supported with the finding that, after oral dosing, only about 1-2.5%% was excreted via bile back to the intestine and 2-3% excreted via urine. If similar routes of excretion are expected for dermally absorbed doses, it would not be possible to find levels of 53% of applied doses in intestine with only 1% excreted via urine. This indicates that about 53% of the dermally applied dose was taken up orally after all. Excretion in bile (1%) and urine (1%) following dermal exposure was similar to that following oral exposure. 

Further information that can be derived is related to the presence of radioactivity in the tape-stripped skin at the application site. This indicates that the radioactivity present in the dermis-epidermis fraction of the skin is bioavailable with time, since the radioactivity levels decreased from 16-20% (24 h after application) to 1.47-2.39% 168 h after the treatment. However, as the actual dermal absorbed dose must have been very small, it is more likely that de decrease of radioactivity is due to the continuous oral uptake from grooming of the dermal application site (Appelqvist, 2006). Further, the DDAC assessment report for Product Type 8 conducted under Directive 98/8/EC (evaluating Competent Authority: Italy, June 2015, attached in Section 13 of the IUCLID dataset), which reported the above study stated that:“The available data do not allow a clear quantification of DDAC percutaneous absorption, although they indicate that there are not marked differences between the oral and the dermal bioavailability. Therefore, it is expected that DDAC dermal absorption is limited to ca.10% at non corrosive concentration (as maximum value).”An additional in vitro dermal absorption study was reported, where following application of 0.1% aqueous concentration of DDAC, the mean total absorbable amount was 9.41% (rounded to 10% at non corrosive concentrations) including the radioactivity present in the dermis and epidermis at the dose site.

Conclusion:Overall, based on the available weight of evidence information, the test substance can be expected to overall have low absorption potential through the dermal route. Therefore, in line with the biocide assessment report and as a conservative approach a maximum oral absorption value of 10% can be considered for risk assessment.  

Inhalation absorption  

Based on physicochemical properties:  

According to REACH guidance document R7.C (ECHA, 2017), inhalation absorption is maximal for substances with VP >25 KPa, particle size (<100 μm), low water solubility and moderate log Kow values (between -1 and 4). Very hydrophilic substances may be retained within the mucus and not available for absorption. 

The test substance, because of its relatively low vapour pressure of 1.34E-4 Pa at 25°C, will not be available as vapours for inhalation under ambient conditions. Therefore, the substance will neither be available for inhalation as vapours nor as aerosols. In case of spraying applications, only coarse droplets would be an exposure potential resulting in very low respiratory fraction. Of the inhalable fraction, almost all droplets are expected to deposit in the upper airways and not reach the deeper lungs. However due to low water solubility, the droplets will not be retained in the mucus and instead will be transported to pharynx and swallowed via the ciliary-mucosal escalator. Therefore, the systemic uptake via respiratory route can be considered to be similar to oral route.   

Conclusion:Overall, based on the available weight of evidence information and the higher vascularity of the inhalation route, the test substance can be expected to have low to moderate absorption potential through the inhalation route, depending on the droplet size. Therefore, a maximum value 50% can be considered for the risk assessment as a conservative approach.  

 

METABOLISM:  

Based on identified literature: 

 

As discussed in the Bosshard & Schlatter, 1982, the analysis of urine metabolites revealed that the read across substance DDAI metabolism probably proceed by oxidation and conjugation reactions analogous to the degradation of the fatty acids by β-oxidation. No 14CO2 was detected in expired air, thus complete oxidation and N-dealkylation of the decyl group is not expected to occur.

A further study to evaluate the metabolic profile of the labelled 14C-residues showed a dose -dependent metabolism in females: more parent compound was metabolized in the single low oral dose than in the single high oral dose. The metabolic process for the read across substance in the rat was found to involve oxidation of the decyl side-chain to a variety of oxidative products. Evidence seems to favour initial hydroxylation of the carbon next to the terminal carbon, followed by formation of a hydroxyketone. The four major metabolites found in this study were more polar and presumed to be less toxic than the parent compound, although their chemical structures were not definitively identified. Under the study conditions, the read across substance was considered to be metabolized via hydroxylation/oxidation to form polar metabolites (Henderson, 1992).

Based on (Q)SAR modelling: 

The OECD QSAR Toolbox was used to predict the first metabolic reaction, using the rat liver S9 metabolism simulator and the in vivo rat metabolism simulator. As shown in the below table, the OECD QSAR Toolbox v.4.4.1 predicted hydroxylation of the penultimate or ultimate position of the alkyl chain to a carboxylic acid group and subsequent break-down of the alkyl chain for the main constituents of the target substance. These results are in agreement with the output generated by Meteor® Nexus from Lhasa. For further details, refer to the read across justification.

Representative constituents		Rat liver S9 metabolism simulator / in vivo rat metabolism
C12-12 DAQ		ω or ω-1 aliphatic hydroxylation
C12-C14 DAQ		ω or ω-1 aliphatic hydroxylation
C12-C16 DAQ		ω or ω-1 aliphatic hydroxylation

Conclusion:Based on all the available weight of evidence information, the test substance is considered to be metabolized by oxidation and conjugation reactions.

DISTRIBUTION 

Based on physico-chemical properties: 

According to REACH guidance document R7.C (ECHA, 2017), the smaller the molecule, the wider the distribution. Small water-soluble molecules and ions will diffuse through aqueous channels and pores, although the rate of diffusion for very hydrophilic molecules will be limited. Further, if the molecule is lipophilic (log P >0), it is likely to distribute into cells and the intracellular concentration may be higher than extracellular concentration particularly in fatty tissues. Identification of the target organs in repeated dose studies are also indicative of the extent of distribution. 

Generally given the ionic nature of the test substance, the test substance is not likely to readily partition across the blood membranes into the different organs, leading to an overall low distribution potential. Moreover, even if the test substance distributes to a certain extent, it is not expected to bioaccumulate based on the read across experimentalBCF values of C16-18 DAQ or the predicted BCF values generated for the test substance using ionic BCF regression-based equation from BCFBAF v. 3.02 program of EPISuite^TM(see section 4.3 of the CSR). 

Based on experimental data on read across substances: 

As discussed above, n the Appelqvist, 2006 study, quantifiable levels of radioactivity were found in some central organs at 8 h post-dosing(intestines, liver. kidney);otherwise, the majority of the dose was confined to the intestines, where levels decreased over time.

Conclusion:Based on all the available weight of evidence information, the test substance is expected to have a low distribution and bioaccumulation potential.  

EXCRETION: 

Based on physicochemical properties: 

Given the expected low absorption potential of the test substance due to its ionic nature and physico-chemical properties, it can be expected to be primarily excreted through faeces. 

Based on experimental data on read across substances: 

Based on the evidence from the available read across oral studies (Bosshard & Schlatter, 1982, Henderson, 1992,Appelqvist, 2006), the test substance is primarily expected in faeces (>90%) and less via urine (<10%).Further, in these studies no radioactivity was found in the expired CO2, thus indicating absence of complete oxidation of the alkyl chains. 

Conclusion:Based on all the available weight of evidence information, the test substance is expected to be primarily excreted via faeces.  

 

[1] Log Kp = -2.80 + 0.66 log kow – 0.0056 MW