7a-ethyldihydro-1H,3H,5H-oxazolo[3,4-c]oxazole

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD guideline and in accordance with GLP

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

no

Test guideline 2

Guideline:

EPA OPPTS 870.7485 (Metabolism and Pharmacokinetics)

Test guideline 3

Guideline:

EU Method B.36 (Toxicokinetics)

Principles of method if other than guideline:

Test guideline followed

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

7a-ethyldihydro-1H,3H,5H-oxazolo[3,4-c]oxazole

EC Number:

231-810-4

EC Name:

7a-ethyldihydro-1H,3H,5H-oxazolo[3,4-c]oxazole

Cas Number:

7747-35-5

Molecular formula:

C7H13NO2

IUPAC Name:

7a-ethyl-tetrahydro-1H-[1,3]oxazolo[3,4-c][1,3]oxazole

Details on test material:

- Name of test material (as cited in study report): BIOBAN™ CS-1246, biocide
- Molecular formula (if other than submission substance): C7H13NO2
- Molecular weight (if other than submission substance): 143.09
- Physical state: Liquid, pale yellow
- Lot/batch No.: Non-radiolabeled: Lot # TC1031LAH3
Radiolabeled: Registry # DA2459
- Radiochemical purity (if radiolabelling): >98%
- Specific activity (if radiolabelling): Radiolabeled 20.92 mCi/mmol

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Jugular cannulated rats: Taconic (Germantown, New York)
Non-cannulated rats: Charles River (Portage, Michigan)
- Age at study initiation: 9-10 weeks
- Weight at study initiation: Males 234-337g and Females 167-211g
- Fasting period before study: ~16 hours
- Housing: Animals were housed singly in glass Roth-type metabolism cages
- Individual metabolism cages: yes
- Diet (e.g. ad libitum): Certified Rodent Diet, ad libitum
- Water (e.g. ad libitum): Municipal water, ad libitum
- Acclimation period: one week

ENVIRONMENTAL CONDITIONS
Temperature: 18.2 to 24.7°C
Humidity: 38-78%
Air Changes: 12-15 times/hour
Photoperiod: 12-hour light/dark (on at 6:00 a.m. and off at 6:00 p.m.)

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Oral Dose Preparation:
The oral dose solutions were prepared in corn oil. Appropriate amounts of 14C-labeled and/or non-radiolabeled BIOBAN CS-1246 were added to obtain the target doses of 5 or 200 mg BIOBAN CS-1246/kg body weight. Confirmation of the test material concentration in the dose solutions was conducted. Radioactivity in the dose solutions were quantified by liquid scintillation spectrometry (LSS) as described below. The amount of dose solution administered was targeted at ~ 5 g/kg body weight. The target radioactivity was ~125 µCi/kg for both the low and the high dose.

The appropriate quantity of non-radiolabeled test material was dissolved in corn oil to prepare the non-radiolabeled dose solution. Non-radiolabeleddose solution for Group 5 was prepared once, as BIOBAN CS-1246 has been reported to be stable in corn oil.

Duration and frequency of treatment / exposure:

Oral:
Groups 1-4, single oral dose of 14C-BIOBAN CS-1246.
Group 5, 14 daily oral doses of non-radiolabeled BIOBAN CS-1246 followed by a single oral dose of 14C-BIOBAN CS-1246 on day 15.

Doses / concentrations

Remarks:

Doses / Concentrations:
Oral dose administration:
With the exception of Group 5, all animals on the study received a single oral gavage dose. Group 5 animals received 14 daily doses of non-radiolabeled test material. On day 15, each Group 5 animal received a single dose of radiolabeled dose formulation. The volume of radiolabeled dose formulation administered to each animal was calculated based on the body weight taken on the day of the dose administration. The volume of the non-radiolabeled dose administered to each Group 5 animal on days 1 to 14 was based on the body weight taken on day 1 and day 8 of non-radiolabeled dose administration. The actual amount of radiolabeled test material administered to each animal was determined by weighing the dose syringe before and after dose administration. The targeted volume of the radiolabeled dose formulation was 5 mL/kg bw. The amount of non-radiolabeled test material administered to Group 5 animals was determined by drawing the target dose volume of 5 ml/kg in a glass syringe on the basis of their body weight on day 1 and 8 of the study.
All animals were fasted overnight through approximately 4 hours post-dosing except for animals in Group 5, which were fasted only prior to the last dose (radiolabeled test material).

No. of animals per sex per dose / concentration:

4 rats per sex per dose level will be used in this study; except, a probe study consisting of one or more animals may be conducted in order optimize the experimental design of the actual study

Control animals:

yes

Positive control reference chemical:

No data

Details on study design:

- Dose selection rationale:
This study consisted of a blood/plasma 14C concentration-time course (after oral and dermal application) to determine peak (Cmax) blood/plasma 14C concentrations and to determine absorption (including penetration of BIOBAN™ CS-1246 from skin), distribution, metabolism, and elimination of BIOBAN™ CS-1246 following single or multiple doses (see Text Table 1 for detail). For Groups 1, 2, and 5, the study continued until ≥ 95% of the administered dose was recovered in the excreta (168 hour for Group 1 and 144 hour for Groups 2 and 5).

The rats of Groups 1, 2, and 6 were fitted with indwelling jugular vein cannulae and plasma and red blood cell (RBC) 14C concentration-time course evaluated to determine peak (Cmax) and half-peak (½ Cmax) plasma 14C concentrations. Approximately 0.1-0.2- ml blood was collected at chosen times (0.25, 0.5, 1, 2, 4, 6, 12, 24 hour post-dosing and every 24 hour thereafter) and plasma and RBC separated by centrifugation. The RBC was oxidized (OxiMate 80 Sample Oxidizer, PerkinElmer Life Sciences, Inc., Boston, Massachusetts) and the plasma and RBC analyzed for radioactivity by liquid scintillation spectrometry (LSS).

Oral Dose Administration
The oral dose was administered via a ball-tipped gavage needle attached to glass syringe. With the exception of Group 5, all animals on the study received a single dose. Group 5 animals received 14 daily doses of non-radiolabeled test material. On day 15, each Group 5 animal received a single dose of radiolabeled dose formulation. The volume of radiolabeled dose formulation administered to each animal was calculated based on the body weight taken on the day of the dose administration. The volume of the non-radiolabeled dose administered to each Group 5 animal on days 1 to 14 was based on the body weight taken on day 1 and day 8 of non-radiolabeled dose administration. The actual amount of radiolabeled test material administered to each animal was determined by weighing the dose syringe before and after dose administration. The targeted volume of the radiolabeled dose formulation was 5 g/kg bw. The amount of non-radiolabeled test material to Group 5 animals was determined by drawing the target dose volume of 5 ml/kg in a glass syringe on the basis of their body weight on day 1 and 8 of the study.
All animals were fasted overnight through approximately 4 hours post-dosing except for animals in Group 5, which were fasted only prior to the last dose (radiolabeled test material).


Dose Levels and Justification:
This study was conducted on low (5 mg/kg; Groups 1, 3-6) and high (200 mg/kg; Group 2) dose levels of BIOBAN™ CS-1246. Low dose of 5 mg/kg was lower than NOEL and high dose where an effect was observed (in a 90-day repeated-dose toxicity study, Stebbins et al., (2007) found the NOEL to be 10 mg/kg/day and a thickened limiting ridge of the stomach in all males and females given 250 mg/kg/day.)

Details on dosing and sampling:

Specimen Collection:

Urine:
All urine voided during the study was collected in dry-ice cooled traps. The urine traps were changed at 12-, 24- and 48-hour post-dosing followed by 24-hour intervals for the remainder of the study. The cages were rinsed with water at the time the traps were changed and the rinse collected. Each urine specimen and urine/cage rinse was weighed, and a weighed aliquot analyzed for radioactivity by LSS as described below. Urine was collected 6 hours post-dosing for the Group 4. Equal volume aliquots of urine samples (per time, dose and sex) from the 0-12-hour and 12-24-hour
collection intervals was pooled and stored at -80ºC and selected urine samples underwent chemical analysis.

Feces:
Feces were collected in dry-ice chilled containers at 24-hour intervals. An aqueous homogenate (~ 25% w/w) was prepared (shaken for > 4 hours) and weighed aliquots of these homogenates was oxidized and quantitated for radioactivity by LSS. Feces were collected 6 hours post-dosing for the Group 4. In addition, equal volume aliquots of fecal homogenates from each animal were taken from the 0-24-hour collection interval and pooled (per dose and sex). These pooled samples were stored at -80ºC for chemical analysis. Inadvertently, Group 1 samples were stored at –20oC.

Expired Volatiles:
Air was drawn through the cage at approximately 850 ml/minute. A probe experiment was conducted to determine volatiles (in the expired air or from the application site skin) in the air drawn through the cage. One rat was administered BIOBAN™ CS-1246 via oral gavage and skin from one rat was used for dermal application; both were kept separately in metabolism cages and the air exiting the cage was passed through charcoal traps. The charcoal traps were changed at 24-hour intervals. The charcoal was ground with a blender and weighed aliquots oxidized and analyzed for radioactivity. In the orally dosed rat, ~0.2% of the administered dose was trapped in charcoal over 48 hours, therefore, no charcoal trap was used in the actual experiments. A significant amount of radioactivity (17%)was trapped in the charcoal from the dermal application skin site and therefore, charcoal traps were used in the actual study animals for the dermal exposure (Group 6). Recovery of the dermally applied dose was low (66-71%); therefore, several other
trapping agents (i.e., silica and chromosorb) in addition to charcoal were used. In addition to passing the exiting air through a series of traps, the trapping agents were also extracted in suitable solvents to determine the lost radioactivity.

Expired CO2:
Expired CO2 was not collected from any orally dosed animals because it was determined that <1% was recovered in the probe experiment. For group 6 only, following the charcoal trap (described above) the expired air was passed through a solution of monoethanolamine:1-methoxy-2-propanol (3:7 v/v) to trap expired CO2 and analyzed for radioactivity. The CO2 trap was changed only at the 12-hour and 24-hour intervals for Group 6 because < 1% of the administered dose was detected in the CO2 trap during the preceding interval, the replacement traps were not analyzed for radioactivity.

Terminal Sacrifice:
At the specified time (168 hours post-dosing for Group 6 or when ≥95% of the administered radioactivity was recovered in urine, feces, and expired air for Groups 1, 2, and 5) after dosing, animals were anaesthetized with CO2/O2 and sacrificed by exsanguination. Animals from Group 3 were sacrificed at the time point (0.25 hour post-dosing) at which the maximum concentration (Cmax) was measured in Group 1. Because the test material was cleared from the system rapidly reaching Cmax in < 1 hour and to ½Cmax in < 2 hours of dosing, animals in Group 4 were sacrificed 6 hours after dosing in order to provide scientifically sound data pertinent to the time-course fate of the test material in tissues of the test animals. Following sacrifice, the Roth cages or plastic tubs (Group 3) were washed and the cage wash analyzed for radioactivity.


Tissues:
The following tissues were collected at sacrifice:
Adrenal blood (RBC and plasma)
Brain Carcass (residual)
Fat (perirenal)
GI tract (with contents)
Kidney
Liver
Ovary
Skin
Spleen
Stomach (without contents)
Testis
Thyroid
Uterus


Final Cage Wash:
Following the terminal sacrifice of the animals, a final cage wash (FCW) was performed. The final cage wash and contents were collected and the weight of the sample was determined. The FCW and contents were shaken for > 4 hours. A weighed aliquot of the FCW was analyzed for radioactivity.

Plasma
Blood was obtained at sacrifice via cardiac puncture and/or inferior vena cava and/or dorsal aorta. The blood was centrifuged to separate plasma and plasma analyzed for radioactivity. Equal volume aliquots of plasma collected from Groups 3 and 4 was pooled (per time, dose and sex) and stored at –80ºC, however the samples could not be analyzed because of low radioactivity.

Control Samples:
Control urine and feces were collected for 24 hours in dry-ice cooled traps from one male and one female rat not dosed with 14C- BIOBAN™ CS-1246 and not fasted prior to sample collection. The control animals were sacrificed and plasma collected by the same procedure as the dosed animals.

Sample Analysis:
14C Analysis: Radioactivity was quantified in a liquid scintillation spectrometer. Counts per minute (cpm) were corrected for quench and converted to disintegrations per minute (dpm). Samples with dpm less than twice the concurrently run background were considered to contain insufficient radioactivity to reliably quantify for all the groups with the exception of Group 6. Samples collected from Group 6 were counted for longer periods of time (e.g., 2 hour/sample) once they normally become below twice the background levels. This was to confirm that extremely low levels of the applied radioactivity is not moving into blood stream from the deeper layers of skin. The subsequent samples after counting the last sample that did not accumulate enough cpm over 2 hours to become above the background were counted normally. This, along with collection of samples for 7 days instead of terminating the study upon recovery of ≥95% of the dermally applied dose, allowed for accurate determination of any influx of the residual radiolabeled test material through the skin.

Statistics:

Descriptive statistics was used, i.e., mean ± standard deviation. All calculations in the database were conducted using Microsoft Excel spreadsheets and databases in full precision mode (15 digits of accuracy). Certain pharmacokinetic parameters were estimated for both blood (plasma and RBC) and urine data, including AUC (area-underthe- curve), Cmax, and elimination rate constants, using a pharmacokinetic computer modeling program. Pharmacokinetic analysis of the time-course plasma and RBC data of Groups 1 and 2 and RBC data of Group 6 was performed using a two-compartmental
model that better described the data. Pharmacokinetic analysis of the time-course plasma data of Group 6 rats was performed by using one-compartmental model which described the data better than a two-compartmental model, as radioactivity dropped below the limit of quantification within 24-48 hours post-dosing. In contrast, the radioactivity in RBC of the rats dosed dermally remained above the limit of detection during the course of the
study (168 hour post-dosing). For pharmacokinetic analysis, WinNonLin v. 5.0.1 (Pharsight Corp., Mountain View, California) computer modeling software was used.

Results and discussion

Preliminary studies:

Dose Solution (Concentration, Stability, Administration and Recovery of the Dose):

The concentration of BIOBAN™ CS-1246 in the various dose solutions is shown in Table 1. The measured concentration of total test material in each dose solution was within 10% of the target concentration (Beuthin 2008a-e). The concentration of radioactivity in each of the dose solutions was within 10% of the target radioactivity, except for the Group 1 dose, which was within 25% of the nominal value BIOBAN™ CS-1246 was determined to be stable in corn oil for 25 days at concentrations encompassing those used in the oral dose solutions (Stebbins and Card, 2006).

The mean body weight (BW), mean amounts of BIOBAN™ CS-1246 and mean radioactivity actually administered to each group of rats are presented in Table 2 and the individual animal data are presented in Appendix Tables 1-6. At the time of 14CBIOBAN ™ CS-1246 dosing, the body weights of male and female rats ranged from 0.234-0.337 and 0.167-0.211 kg, respectively. The mean dose of 14C-BIOBAN™ CS- 1246 administered to various groups ranged from 4.5-6.5 mg/kg for the targeted 5.0 mg/kg dose and from 212-215 mg/kg for the targeted 200 mg/kg dose (Table 2). The rats of the repeated dose (Group 5) received 14 daily doses of 4.5-5.3 mg unlabeled BIOBAN™ CS-1246 /kg prior to receiving 6.2-6.5 mg/kg 14C-BIOBAN™ CS-1246 (Table 2).

An average of 122-136 μCi/kg (or, ~34 μCi per rat) was administered to male rats of the oral dose groups; female rats received 126-143 μCi/kg (or, ~24 μCi per rat). The actual radioactivity administered to rats through oral dosing was consistent with the targeted dose of ~125 μCi/kg. The difference between the target and actual doses administered had no effects on the results of this study. There were no signs of toxicity observed in any animals following oral administration of either 5 or 200 mg 14CBIOBAN CS-1246™/kg.

The mean total recovery of radioactivity from all oral dose groups ranged from 91-109% (34 animals out of 40 were between 94 and 101%) of administered dose.

Main ADME results

Main ADME results 1

Type:

absorption

Results:

The orally absorbed dose was rapidly excreted in urine (83-97%) without any gender difference. Elimination of the dermally applied dose was low accounting for only 17-20%. Total fecal elimination of the dermal dose was only 4%.

Main ADME results 2

Type:

distribution

Results:

Only ~1% of the administered 14C-BIOBAN™ CS-1246 biocide remained in the tissues after 144 (high single dose) or 168 (low single or multiple dose) hours post-dosing.

Main ADME results 3

Type:

metabolism

Results:

The absorbed test material was completely metabolized, affording 2-amino-2-ethyl-1,3- propanediol (AEPD) as the only metabolite above 5% of the administered dose in all urine and fecal samples analyzed from all dose groups.

Main ADME results 4

Type:

excretion

Results:

Elimination of the radioactivity from plasma was biphasic with most of the elimination occurring during the rapid (α) elimination phase (t½α = 0.1-0.5 hours), with a slower (β) elimination phase (t½β = 4-5 hours).

Toxicokinetic / pharmacokinetic studies

Details on absorption:

Absorption of the oral doses was estimated from the percent of administered radioactivity recovered in urine and rinse, final cage wash and tissues at sacrifice (i.e., sum of all sample matrices except feces). From the sum of radioactivity (as percent of administered dose) associated with those matrices, it is concluded that 92 and 86% (for male and female rats, respectively) of the single oral dose of 5 mg BIOBAN™ CS-1246 /kg (Group 1) was systemically absorbed. Absorption of BIOBAN™ CS-1246 after multiple 5 mg/kg oral doses (Group 5) was higher (96 and 99% of dose, for male and female rats, respectively) than the single oral dose. Absorption of the single oral high dose of 200 mg/kg (Group 2) was 85 and 90% of administered dose for male and female rats, respectively.

Details on distribution in tissues:

Disposition of the Administered 14C-BIOBAN™ CS-1246 in Tissues:
The distribution of radioactivity in tissues after the administration of 14C- BIOBAN™CS-1246 is presented in Table 3 (as percent of administered dose) and in Table 4 (as microgram equivalent BIOBAN™ CS-1246 per gram of tissue). While most tissues from animals of all groups contained quantifiable radioactivity, some tissues, containing less than 0.005% of the administered dose, appear as 0.00% in the tables.

Group 1. Low Single Oral Dose of 14C- BIOBAN™ CS-1246:
On average, a total of 1% of the 5 mg/kg single oral dose of 14C- BIOBAN™ CS- 1246 remained in tissues 168 hours after dosing, most of which was found in the residual carcass and skin (0.7-0.8% and 0.3% of the administered dose, respectively) (Table 3). The concentrations of radioactivity measured in tissues at terminal sacrifice, and expressed as μg 14C- BIOBAN™ CS-1246 equivalent/g of tissue are presented in Table 4. For males, the highest concentrations ranked from skin (0.055 μg/g) > carcass (0.049 μg/g) > kidney (0.025 μg/g) > testes (0.024 μg/g) > liver (0.021 μg/g).
A similar rank order (and concentration) was observed for tissues from females, with the highest tissue concentrations ranked from skin (0.065 μg/g) > carcass (0.055 μg/g) > kidney (0.022 μg/g) = stomach tissue (0.022 μg/g).

Group 2. High Single Oral Dose of 14C- BIOBAN™ CS-1246:
On average, a total of 1% of the 200 mg/kg single oral dose of 14C-BIOBAN™ CS- 1246 remained in tissues 144 hours after dosing. Consistent with that observed for low-dosed animals, most was recovered in the residual carcass and skin (~0.7-0.8% and 0.2% of administered dose associated with each of those tissues) (Table 3). For males, the highest concentrations, expressed as μg 14C- CS-1246™ equivalent/g of tissue, ranked from kidney (2.4 μg/g) ≥ carcass (2.3 μg/g) ≥ testes (2.3 μg/g) > skin (1.5 μg/g) > brain (1.1 μg/g). A similar rank order (and concentration) was observed
for tissues from females, with the highest tissue concentrations ranked from kidneys (6.7 μg/g) > carcass (2.6 μg/g) > skin (2.0 μg/g) > brain (1.5 μg/g) (Table 4).

Group 3. Low Single Oral Dose of 14C-BIOBAN™ CS-1246; Sacrificed at Cmax:
As would be expected, a higher percentage of administered radioactivity was associated with tissues of animals sacrificed at 0.25 hours post-dosing. On average, 91-94% of the dose remained inside the animals’ body at tmax (0.25 hour post-dosing) (Table 3). Most remained unabsorbed and recovered from the GI tract (69% of administered dose). Besides residual carcass, most of the absorbed dose was found in skin > liver > kidney. As expected, most (~69%) of the radioactivity was found in the GI tract and liver (~2%) as the process of absorption was underway from the GI tract to liver through hepatic portal system. Higher levels of radioactivity in kidney (0.5-1.3%) was due to rapid elimination of the absorbed 14C-BIOBAN™ CS-1246 in urine through kidneys. Higher percent dose in skin (3-4%) than liver and kidney was unexpected and cannot be explained from these data (Table 3).

Group 4. Low Single Oral Dose of 14C-BIOBAN™ CS-1246; Sacrificed at 6 Hours Post-Dosing:
On average, 37% of the 5 mg/kg single oral dose of 14C-BIOBAN™ CS-1246 remained in the bodies of animals sacrificed at 6 hours post-dosing tmax), or ~40% of the radioactivity remained inside the body of animals sacrificed at tmax (0.25 hour post-dosing). Most (~15% of administered dose) was found in the GI tract. Besides residual carcass, most of the radioactivity was found in whole liver > total skin > whole kidney.
Again, as expected from significant (~15% of the dose) amount of 14C-BIOBAN™ CS-1246 remaining in the GI tract and its continuous absorption andactive elimination, higher radioactivity was detected in stomach (1-2%), liver (3-5%; site of passage of all GI absorption) and in kidney (~1%; primary elimination site). Higher levels of radioactivity in liver > skin > kidney was somewhat consistent to that observed in animals sacrificed 0.25 hours post-dosing.

Group 5. Low Multiple Oral Dose of 14C-BIOBAN™ CS-1246:
On average, a total of 1% of the 5 mg/kg final (15th) oral dose of 14C-BIOBAN™ CS- 1246 remained in tissues 168 hours after dosing (similar to that observed for Groups 1 and 2 animals). Consistent with that observed for low, single-dosed animals, most was recovered in the residual carcass and skin (0.8% and 0.1% of administered dose associated with each of those tissues). Tissue residue concentrations from the multiple-dosed animals followed a similar general rank order as observed from singly dosed animals. For males, the highest concentrations ranked from carcass (0.08 μg/g) > liver (0.06 μg/g) > kidney (0.05 μg/g) > testes (0.043 μg/g) > skin (0.041 μg/g). For females, tissue concentrations ranked from carcass (0.08 μg/g) >stomach tissue (0.05 μg/g) > kidney (0.04 μg/g) = brain (0.04 μg/g) ≥ skin (0.04 μg/g).

Details on excretion:

Urinary Elimination of the Administered 14C-BIOBAN CS-1246™:
The amounts of BIOBAN™ CS-1246-derived radioactivity excreted in urine during successive 12- or 24-hour collection intervals are shown in Table 3 and Appendix Tables 1-6. Urinary data at each time interval is the sum of radioactivity found in the collected urine sample plus cage rinse.
Following a single oral dose of 14C- BIOBAN™ CS-1246 (Group 1), a total of 90 and 83% percent of the dose was recovered in urine of male and female rats, respectively (Table 3, Appendix Table 1). Radioactivity was rapidly excreted. In Group 1 male rats, 70% of administered dose was excreted within 12-hours of dosing; an additional 11% of administered dose was collected between 12-24 hours post-dosing (accounting for 81% of total urinary recovery within 24 hours post-dosing). Urinary excretion in Group 1 female rats was comparable to that of males, with 64% of administered dose excreted within 12-hours of dosing; an additional 9% of administered dose (accounting to 73% of total urinary recovery) was recovered in 12-24 hours post-exposure urine. Recovery of the radioactivity in the urine of rats dosed for 14 days with non-radiolabeled test compound followed by a single dose of 14C- BIOBAN™ CS-1246 on day 15 (Group 5) was 93 and 97% of the dose for the males and females, respectively. Of the total radioactivity recovered in urine, 75% was excreted within 12 hours post-dosing (for both males and females) and additional 10% in the 12-24 hour interval. Rapid urinary
elimination of the absorbed dose was quite apparent from the recovery of a very high (~43% of the dose) amount of radioactivity from the urine of rats sacrificed 6 hours postdosing
(Group 4).
Urinary elimination of the high dose of 200 mg 14C- BIOBAN™ CS-1246/kg (Group 2) was 82 and 87% of the administered dose for the male and female rats, respectively (Table 3). For males, 61% of total radioactivity recovered in urine was excreted within 12 hours post-dosing, and 12% between 12 and 24 hours. For females, 66% of total radioactivity recovered in urine was excreted within 12 hours post-dosing, and 11% between 12 and 24 hours. A much lower percent of the administered radioactivity was recovered in the urine of the dermally dosed (Group 6) rats. Over the 168-hour collection period, 19% and 15% of administered dose was recovered in urine of males and females, respectively. Furthermore, the appearance of radioactivity in urine was slower than that observed for the oral dose groups, with only 9-11% of the administered dose excreted within the first 24 hour (accounting for 46-65% of the total radioactivity excreted over the entire collection period). Total urinary elimination accounted for 64-80% of the absorbed dose during the course of the study. Slow and low urinary elimination was consistent with pattern of slow penetration of the applied dose from the dermal site of application and limited absorption of the applied dose, as expected due to cornified layer of cells on the skin surface that work as a barrier slowing skin penetration of xenobiotics.

Fecal Elimination of the Administered 14C-BIOBAN™ CS-1246:
The mean fecal elimination of the administered 14C- BIOBAN™ CS-1246-derived radioactivity is presented in Table 3 (and Appendix Tables 1-6).
A small percentage (compared to recovery in urine) of the orally dosed 14C-BIOBAN™ CS-1246 was eliminated in feces, ranging from an average of 9-15% of the administered dose after a single oral dose (of either 5 or 200 14C-BIOBAN™ CS-1246/kg) and 11-13% after multiple dosing. The 14C-BIOBAN™ CS-1246-derived radioactivity recovered in feces of the dermal group (Group 6) was only 4%.

Toxicokinetic parameters

Toxicokinetic parameters 1

Toxicokinetic parameters:

Cmax: All the groups

Toxicokinetic parameters 2

Toxicokinetic parameters:

Tmax: All the groups

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

The absorbed test material was completely metabolized, affording 2-amino-2-ethyl-1,3- propanediol (AEPD) as the only metabolite above 5% of the administered dose in all urine and fecal samples analyzed from all dose groups. Four minor metabolites were also observed above 0.5% of the administered dose, but not identified.

Any other information on results incl. tables

Refer below attachments:

Attachment 1. Text Table.1 Study Design

Attachment 2: BIOBAN™ CS-1246 BIOCIDE: PHARMACOKINETICS AND METABOLISM IN CRL:CD(SD) RATS

Time-Course Concentration of Radioactivity and Pharmacokinetics in Plasma Oral Doses of 14C- BIOBAN™ CS-1246:

The plasma concentrations of 14C- BIOBAN™ CS-1246-derived radioactivity, expressed as μg-equivalent/g plasma, the data presented in Table 5. The kinetic parameters for the plasma concentration-time profiles of 14CBIOBAN ™ CS-1246 of Groups 1 and 2 rats were derived by a two-compartmental model, which better described the data than a single-compartment model. The derived pharmacokinetic parameters of plasma time-course 14C activity in rats are presented in Table 6. The orally administered BIOBAN™ CS-1246 was rapidly absorbed without any apparent lag time and achieved the highest measured concentration (Cmax) within 0.25 hours (tmax), the first collected blood sample. The highest mean plasma concentrations for males were 2.1±0.6 μg/g (Group 1) and 60.2 ± 22.7 μg/g (Group 2) and for females were 1.8±0.2 μg/g (Group 1) and 44.7±17.5 μg/g (Group 2). On the basis of these results rats in Group 3 were sacrificed 0.25 hours post-dosing (at tmax). As the absorbed radioactivity was rapidly eliminated (t½ of α elimination phase, which accounted for majority of the elimination of the absorbed dose, of <0.5 hour) the calculated ½Cmax would have been <1 hour, therefore, the Group 4 animals were sacrificed 6 hours post-dosing to provide better information on the fate of the absorbed dose in tissues.

For the Group 1 rats, model predicted slightly higher plasma Cmax (2.9±0.8 μg/g [male] and 2.9±0.2 μg/g [female]) of 14C-BIOBAN™ CS-1246 derived radioactivity than the observed (2.1±0.6 μg/g [male] and 1.8±0.2 μg/g [female]) (Tables 5 and 6). Elimination of the radioactivity from plasma was biphasic with most of the elimination occurring during the rapid (α) elimination phase. The plasma elimination t½α was between 0.3 and 0.5 hours for both male and female rats (Table 6). Consistent with the rapid elimination of BIOBAN™ CS-1246 from plasma, concentration was dropped by 3- to 6-fold within 4 hours and 7- to 12-fold within 8 hours post-dosing (Table 5). The remaining residual radioactivity was eliminated,

mostly after 12 hours of dosing, by the slow (β) elimination phase. The plasma elimination t½β was ~4 hours (Table 6). There was some indication of enterohepatic circulation of the biliary eliminated radioactivity between 2-6 hours post-dosing (Table 5, Figure 1). The AUC of radioactivity at 5 mg/kg oral dose was 5.5±0.8 μg h g-1 (male) and 6.4±0.5 μg h g-1 (female); similarly, total body clearance of BIOBAN™ CS-1246 was 846±116 ml kg-1 h-1 and 757±52 ml kg-1 h-1 (Table 6).

Similar to the low dose of Group 1, the tmax for the highest plasma concentration of 14C-BIOBAN™ CS-1246 derived radioactivity in the high dose Group 2 animals was 0.25 hour post-dosing; within the time of first sample collection (Tables 5 and 6, Figure 1). Again, the model predicted slightly higher Cmax than the observed values (Tables 5 and 6). The model predicted Cmax for the high dose was 27-34 fold higher than the low dose; slightly below the dose proportionality expected from the difference in the dose. The absorbed radioactivity was eliminated by the two distinct

phases (α and β), similar to that observed for the low dose group animals (Table 5, Figure 1). The t½α of 14C-BIOBAN™ CS-1246 derived radioactivity from plasma was 0.1-0.2 hours (Table 5, Figure 5). Most of the rapid elimination of radioactivity from plasma occurred within the first 6 hours post-dosing (4- to 6-fold drop in concentration from the observed Cmax within 6 hours), even with pronounced enterohepatic circulation, which resulted in higher plasma concentration of radioactivity during that same period (Table 5, Figure 1). The rate of elimination of radioactivity during α phase for the Group 2 (high dose) was slightly faster than the Group 1 (low dose) (Table 6). At the high dose, enterohepatic circulation of the biliary eliminated radioactivity became very apparent. Enterohepatic circulation is normally become more apparent at the high doses due to higher amount (40-fold higher in this case between low [5 mg/kg] and high [200 mg/kg] doses) become available for circulation resulting in appearance of much higher secondary peaks. The plasma elimination t½β was ~5 hours (Table 6). The AUC of radioactivity at 200 mg/kg oral dose was 270±28 μg h g-1 (male) and 281±26 μg h g-1 (female), which was 44-49 fold higher than the low dose of 5 mg/kg, consistent with the 40-fold

difference between the two doses (Table 6). Consistent with the dose dependent increase in the AUC and non-saturated kinetics of BIOBAN™ CS-1246 at 5 and 200 mg/kg dose, the total body clearance remained unchanged (793±64 ml kg-1 h-1 [male] and 772±67 ml kg-1 h-1 [female]) between the two doses (Table 6).

Time-Course Concentration and Pharmacokinetics of Radioactivity in RBC Oral Doses of 14C-BIOBAN™ CS-1246:

The RBC of Groups 1, 2, and 6 were oxidized and the radioactivity determined by LSS. The results, expressed as μg 14C-BIOBAN™ P-1487 equivalent/g RBC, are summarized in Table 5. The time-course 14C concentrations in RBC roughly paralleled the plasma time-course concentration profiles including the enterohepatic circulation. In few of the Group 2 animals, a secondary peak, due to enterohepatic circulation occurred between 1 and 2 hours post-dosing, was equal or even higher than the observed Cmax at 0.25 hours. These later occurring peaks in few of the Group 2 animals gave an impression that actual Cmax occurred 1-2 hours post-administration; however, they were only due to the enterohepatic circulation. Similar to the plasma, RBC data was also best described by a two-compartment pharmacokinetic model.

The modeled Cmax of radioactivity in RBC was 34-47% (Group 1) and 17-38% (Group 2) lower than the levels found in plasma (Tables 6 and 7). Elimination of the RBC-bound radioactivity was biphasic with a rapid α (t½ = 0.1-1.4 hours) and a slower β (t½ = 20-24 hours) (Table 7). The β elimination phase of radioactivity from RBC was ~4-fold longer than was observed from plasma, consequently, the total body clearance of radioactivity from RBC was 2.6- to 3.0-fold slower than was from plasma (Tables 6 and 7). Due to longer residence time of radioactivity in RBC (28-32 hours for RBC versus 4-8 hours for plasma), the AUC of radioactivity in RBC was 2.8- to 3.1-fold larger than in plasma (Tables 6 and 7).

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): no bioaccumulation potential based on study results
In summary, administered BIOBAN™ CS-1246 biocide was rapidly absorbed, completely metabolized and readily eliminated from the rat within 144-168 hours after dosing, animals were almost free of radioactivity (1-3% total in the body). These data suggest that accumulation of BIOBAN™ CS-1246 biocide would not occur upon exposure.

Executive summary:

The purpose of this study was to provide data on the absorption, distribution, metabolism, and elimination (ADME) of BIOBAN™ CS-1246 biocide hereafter referred to as BIOBAN™ CS-1246 following oral gavage or dermal administration to rats in support of registration (OPPTS Guideline 870.7485, OECD Guideline 417 & 427, EC, Guideline B.36)

This study was conducted to determine absorption, distribution, metabolism, and excretion of 14C-BIOBAN™ CS-1246 following oral exposure to groups (n = 4) of male and female Crl:CD(SD) rats. Orally administered BIOBAN™ CS-1246 was rapidly absorbed without any apparent lag time. Absorption of the oral dose (5 or 200 mg/kg) was 85-99%. Total recovery of radioactivity from the orally dosed rats was 91-109% of the administered dose.

The orally absorbed dose was rapidly excreted in urine (83-97%) without any gender difference. Most of the urinary elimination (61-75%) occurred within 12 hours (~43% within 6 hours) of dosing with additional 9-12% during 12-24 hours post-dosing. Only a small percent (9-15%) of the oral dose was eliminated in feces.

Only ~1% of the administered 14C-BIOBAN™ CS-1246 remained in the tissues after 144 (high single dose) or 168 (low single or multiple dose) hours post-dosing.

In the rats dosed orally with 14C-BIOBAN™ CS-1246, elimination of the radioactivity from plasma was biphasic with most of the elimination occurring during the rapid (α) elimination phase (t½α = 0.1-0.5 hours), with a slower (β) elimination phase (t½β = 4-5

hours). There was some indication of enterohepatic circulation of the biliary eliminated radioactivity between 2-6 hours post-dosing in the low-dose rats, which became pronounced at the high dose. The AUC of radioactivity in plasma at the high dose was 270-281 μg h g-1, which was largely dose proportional; 44-49 fold higher than that ™ Trademark of The Dow Chemical Company ("Dow") or an affiliated company of Dow observed at the low dose. Consistent with dose proportionally of Cmax, AUC and unsaturated kinetics between the low and high doses, clearance remained unchanged between the two doses.

Test-material derived radioactivity was also present in RBC, with Cmax concentrations ~75% of the levels seen in plasma. The time-course radioactivity in RBC roughly paralleled the plasma time-course concentration profiles at much lower concentrations. Kinetics (absorption, elimination t½, AUC, clearance) of radioactivity from RBC were slower than plasma as detectable levels of radioactivity were found in RBC for extended period of time when compared to plasma.

The absorbed test material was completely metabolized, affording 2-amino-2-ethyl-1,3 - propanediol (AEPD) as the only metabolite above 5% of the administered dose in all urine and fecal samples analyzed from all dose groups. Four minor metabolites were also

observed above 0.5% of the administered dose, but not identified.

In summary, administered BIOBAN™ CS-1246 was rapidly absorbed, completely metabolized and readily eliminated from the rat Within 144-168 hours after dosing, animals were almost free of radioactivity (1-3% total in the body). These data suggest that accumulation of BIOBAN™ CS-1246 would not occur upon exposure.