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Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was selected as the key study because the information provided for the hazard endpoint is sufficient for the purpose of classification and labelling and/or risk assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Objective of study:
toxicokinetics
Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 417 (Toxicokinetics)
Deviations:
no
Remarks:
The study was conducted according to the guideline in effect at the time of study conduct.
Qualifier:
according to
Guideline:
EPA OPPTS 870.7485 (Metabolism and Pharmacokinetics)
Deviations:
no
Remarks:
The study was conducted according to the guideline in effect at the time of study conduct.
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Purity: 28 wt%

Radiolabelling:
no

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories International, Inc.
- Age at study initiation: single oral dose and intravenous administration - approximately 11 weeks old.
14-day repeated oral gavage - approximately 9 weeks
- Weight at study initiation: Individual body weights on the first day of test substance administration ranged from 285.5 g to 364.2 g in male animals and from 209.5 g to 237.2 g in female animals.
- Fasting period before study: Animals for the single dose oral gavage and intravenous administration experiments were fasted (approximately 16 ± 2 hours) before dosing with test substance. Animals for the repeated dose 14-day oral gavage experiment were not fasted before dosing with the test substance. The duration of fasting is documented in the study records. Food was returned approximately 2 hours post dose.
- Housing: During the acclimation period, animals were group housed (non-cannulated) or housed individually (cannulated) in solid-bottom caging with Bed-O-Cob® and Nestlets.
- Individual metabolism cages: no
- Diet: PMI® Nutrition International, LLC Certified Rodent LabDiet® 5002 ad libitum,
- Water: tap water ad libitum.
- Acclimation period: quarantined for at least 6 days (groups 1,2 and 4); quarantined for at least 4 days (group 3, shorter quarantine period to ensure cannula patency)


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-26ºC
- Humidity (%): 30-70%
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): approximate 12-hour light/dark cycle

Administration / exposure

Route of administration:
other: oral gavage; intravenous
Vehicle:
other: oral gavage - deionized water; intravenous - 20% dimethyl sulfoxide in deionized water
Details on exposure:
PREPARATION OF TEST SUBSTANCE FORMULATION:

The oral gavage doses were prepared with deionized water, adjusted for purity based on the sponsor-reported purity of 28.0% and administered at a volume of 10 mL/kg bw. The intravenous dose was prepared with 20% dimethyl sulfoxide in deionized water and administered at a volume of 2 mL/kg bw.
Duration and frequency of treatment / exposure:
Group 1: Single Dose Oral Gavage
Group 2: Single Dose Oral Gavage
Group 3: Intravenous
Group 4: 14-Day Oral Gavage, daily
Doses / concentrations
Remarks:
Doses / Concentrations:
Group 1: Single Dose Oral Gavage - 30 mg/kg
Group 2: Single Dose Oral Gavage - 1000 mg/kg
Group 3: Intravenous - 5 mg/kg
Group 4: 14-Day Oral Gavage - 30 mg/kg
No. of animals per sex per dose:
4/sex/dose
Control animals:
no
Details on study design:
Dose selection rationale: Dose levels were selected based on previous toxicity studies with this compound. For the single dose oral gavage experiment, two dose levels were selected in order to provide information on the effect of dose on kinetic processes and help in the dose-response assessment of other toxicity studies. The low dose level, 30 mg/kg bw, was selected to coincide with the lowest dose in the 7-day repeat dose range-finding toxicity study by oral gavage in rats. The high dose, 1000 mg/kg bw, which is the maximum recommended dose as outlined in the OECD guideline, Section 4 (Part 417): Toxicokinetics, Guidelines for the Testing of Chemicals (2010). The high dose level of 1000 mg/kg bw is approximately 1/3 of the oral LD50 observed in the acute oral toxicity study (LD50 = 3129 mg/kg). For the intravenous administration experiment, a dose of 5 mg/kg bw was chosen, which is 1/6 of the low dose for the single oral gavage experiment. For the repeated dose 14-day oral gavage experiment, the dose was set to 30 mg/kg bw, which is equal to the low dose for the single oral gavage experiment.
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: blood, plasma, serum
- Time and frequency of sampling: oral gavage - blood was collected via tail vein at 15 and 30 minutes, and at 1, 2, 4, 8, 12, 24, 48, 72, 96, 120, 144, and 168 hours.
intravenous administration - blood was collected via the tail vein at 2, 5, 15, and 30 minutes, and at 1, 2, 6, 12, 24, 48, 72, 96, 120, 144, and 168 hours.
Statistics:
Group data was represented as a mean ± SD as appropriate. Tables and appendices presented in the report were computer generated and values were rounded appropriately for inclusion in the report. Consequently, the application of manual calculation to report values may in some instances yield a minor variation. These occurrences should not be construed as adversely affecting the integrity or interpretation of the data.

Results and discussion

Preliminary studies:
In a 7-day dose range-finding toxicity study by oral gavage in rats, a sex difference was observed in the toxicokinetic behaviour of this test chemical. Therefore, male and female rats were chosen for this study.

Toxicokinetic / pharmacokinetic studies

Toxicokinetic parametersopen allclose all
Test no.:
#1
Toxicokinetic parameters:
Cmax: 30 mg/kg male = 60.9 (± 1.49) ng/mL; 30 mg/kg female = 107 (± 45.2) ng/mL
Test no.:
#2
Toxicokinetic parameters:
Cmax: 1000 mg/kg male = 259 (± 51.4) ng/mL; 1000 mg/kg female = 325 (± 71.9) ng/mL
Test no.:
#1
Toxicokinetic parameters:
Tmax: 30 mg/kg male =10 (± 2.3) hours; 30 mg/kg female = 7.0 (± 5.8) hours
Test no.:
#2
Toxicokinetic parameters:
Tmax: 1000 mg/kg male = 11 (± 9.9) hours; 1000 mg/kg female = 7.0 (± 5.8) hours
Test no.:
#1
Toxicokinetic parameters:
half-life 1st: 30 mg/kg male = 38 (± 1.7) hours; 30 mg/kg female = 25 (± 12) hours
Test no.:
#2
Toxicokinetic parameters:
half-life 1st: 1000 mg/kg male = 29 (± 3.9) hours; 1000 mg/kg female = 21 (± 4.1) hours
Test no.:
#1
Toxicokinetic parameters:
AUC: 30 mg/kg male = 3,140 (± 557) hr x ng/mL; 30 mg/kg female = 3,790 (± 630) hr x ng/mL
Test no.:
#2
Toxicokinetic parameters:
AUC: 1000 mg/kg male = 13,500 (± 1,560) hr x ng/mL; 1000 mg/kg female = 12,400 (± 939) hr x ng/mL
Test no.:
#4
Toxicokinetic parameters:
Cmax: 30 mg/kg male = 209 (± 23.2) ng/mL; 30 mg/kg female = 109 (± 8.38) ng/mL
Test no.:
#4
Toxicokinetic parameters:
Tmax: 30 mg/kg male = 9.0 (± 11) hours; 30 mg/kg female = 3.0 (± 1.2) hours
Test no.:
#4
Toxicokinetic parameters:
AUC: 30 mg/kg male = 12800 (± 1680) hr x ng/mL; 30 mg/kg female = 4570 (± 1160) hr x ng/mL
Test no.:
#4
Toxicokinetic parameters:
other: Elimination t1/2: 30 mg/kg male = 37 (±3.6) hours; 30 mg/kg female = 24 (±4.2) hours

Metabolite characterisation studies

Metabolites identified:
no

Bioaccessibility

Bioaccessibility testing results:
In the single oral dose experiment, bioavailability of the test item decreased from 1.6 (± 0.35) % to 0.20 (± 0.036) % in male rats and 2.7 (± 0.5) % to 0.27 (± 0.034) % in female rats as the dose increased from 30 mg/kg bw to 1000 mg/kg bw, indicating a saturation in absorption.

Any other information on results incl. tables

There were no adverse clinical signs observed for any test groups.

Elimination T1/2 was 37 (± 3.6) and 24 (± 4.2) hours and the AUC values were 12800 (± 1680) and 4570 (± 1160) hr x ng/mL. The AUC value in male rats was 12800 (± 1680) hr x ng/mL, which was approximately 4.1 times greater than 3140 (± 557) hr x ng/mL, the value obtained after the single oral gavage dose. This indicates that there was some accumulation of the test item in male rats following 14-day repeated oral gavage dosing. The AUC value in female rats was 4570 (± 1,160) hr x ng/mL, which was approximately equal to 3790 (± 630) hr x ng/mL, the value obtained after the single oral gavage dose. This indicates that there was no accumulation of the test item in female rats following 14-day repeated oral gavage dosing.

In summary, the pharmacokinetics of the test item showed that 1) the terminal elimination half-life ranged from 28 to 38 hours in males and 21 to 38 hours in females across the different dose groups 2) bioavailability of the test item decreased as the dose increased indicating saturation in absorption 3) the test item did not accumulate in females but did accumulate to a small degree in males following 14-day repeated oral gavage dosing.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): other: the test item did not accumulate in females but did accumulate to a small degree in males following 14-day repeated oral gavage dosing.
This study and the conclusions which are drawn from it fulfil the quality criteria (validity, reliability, repeatability).
The test item did not accumulate in females but did accumulate to a small degree in males following 14-day repeated oral gavage dosing.
Executive summary:

The toxicokinetics of the test substance was studied in male and female Sprague-Dawley rats. Experiments were performed to understand plasma kinetics following single oral gavage, intra venous, or 14-day repeated oral gavage administration. The oral gavage doses were prepared with deionized water, adjusted for purity based on the sponsor-reported purity of 28.0% and administered at a volume of 10 mL/kg bw. The intravenous dose was prepared with 20% dimethyl sulfoxide in deionized water and administered at a volume of 2 mL/kg bw. In a 7-day dose range-finding toxicity study by oral gavage in rats, a sex difference was observed in the toxicokinetic behaviour of this test chemical. Therefore, male and female rats were chosen for this study.

Four male and four female rats were administered the test substance at 30 or 1000 mg/kg bw by single oral gavage. Another four male and four female rats were administered the test substance at 30 mg/kg bw daily by oral gavage for 14 days. Following the last administered dose, blood was collected via tail vein at 15 and 30 minutes, and at 1, 2, 4, 8, 12, 24, 48, 72, 96, 120, 144, and 168 hours. For the intravenous administration experiment, four male and four female rats with surgically implanted jugular vein cannulas were administered test substance through the cannula at 5 mg/kg bw. Following intravenous dosing, blood was collected via the tail vein at 2, 5, 15, and 30 minutes, and at 1, 2, 6, 12, 24, 48, 72, 96, 120, 144, and 168 hours. Blood was processed into plasma, which was stored frozen at ≤ 10ºC until it was analysed by LC/MS/MS. The concentration time course data for plasma from each animal was analysed to determine pharmacokinetic parameters calculated by non-compartmental analysis using a commercially available software program.

The limit of quantitation (LOQ) of test substance in plasma was calculated based on the lowest calibration standard concentration multiplied by the least sample dilution factor of 12. The limit of detection (LOD) was defined to equal 3/10 of the LOQ. Therefore, the LOQ and LOD for test substance in plasma were determined to be 1.20 and 0.360 ng/mL, respectively.

For the intravenous administration experiment, the mean peak plasma concentration (Cmax) was 29100 (± 3400) and 31100 (± 1350) ng/mL in males and females, respectively. The mean terminal elimination half-life (T1/2) values were 28 (± 2.1) and 38 (± 4.3) hours with an area under–the-curve (AUC) value of 33000 (± 4310) and 23300 (± 2360) hr x ng/mL in males and females, respectively. The volume of distribution (V) was 6200 (± 446) and 11900 (± 2050) mL/kg bw and clearance (CL) values were 153 (± 17.9) and 216 (± 21.9) mL/hour/kg bw in males and females, respectively. There was a small sex difference with male rats having an approximately 1.4 times greater AUC and CL value than female rats. For the single dose oral gavage experiment, Cmax at the low dose was 60.9 (± 1.49) and 107 (± 45.2) ng/mL and Cmax at the high dose was 259 (± 51.4) and 325 (± 71.9) ng/mL in males and females, respectively. Mean Tmax values were 10 (± 2.3) and 7.0 (± 5.8) hours at the low dose and 11 (± 9.9) and 7.0 (± 5.8) hours at the high dose in males and females, respectively. The T1/2 values were 38 (± 1.7) and 25 (± 12) hours at the low dose and 29 (± 3.9) and 21 (± 4.1) hours at the high dose in males and females, respectively. The AUC values were 3140 (± 557) and 3790 (± 630) hr x ng/mL at the low dose and 13500 (± 1560) and 12400 (± 939) hr x ng/mL at the high dose in males and females, respectively. Bioavailability of test substance decreased from 1.6 (± 0.35) % to 0.20 (± 0.036) % in male rats and 2.7 (± 0.5) % to 0.27 (± 0.034) % in female rats as the dose increased from 30 mg/kg bw to 1000 mg/kg bw, indicating a saturation in absorption.

For the 14-day repeated dose oral gavage experiment, the Cmax values were 209 (± 23.2) and 109 (± 8.38) ng/mL and Tmax values were 9.0 (± 11) and 3.0 (± 1.2) hours in males and females, respectively. Elimination T1/2 was 37 (± 3.6) and 24 (± 4.2) hours and the AUC values were 12800 (± 1680) and 4570 (± 1160) hr x ng/mL. The AUC value in male rats was 12800 (± 1680) hr x ng/mL, which was approximately 4.1 times greater than 3140 (± 557) hr x ng/mL, the value obtained after the single oral gavage dose. This indicates that there was some accumulation of test substance in male rats following 14-day repeated oral gavage dosing. The AUC value in female rats was 4570 (± 1160) hr x ng/mL, which was approximately equal to 3790 (± 630) hr x ng/mL, the value obtained after the single oral gavage dose. This indicates that there was no accumulation of test substance in female rats following 14-day repeated oral gavage dosing.

In summary, the pharmacokinetics of the test substance showed that 1) the terminal elimination half-life ranged from 28 to 38 hours in males and 21 to 38 hours in females across the different dose groups 2) bioavailability of the test substance decreased as the dose increased indicating saturation in absorption 3) the test substance did not accumulate in females but did accumulate to a small degree in males following 14-day repeated oral gavage dosing.