Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02.09. - 24.09.1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: OECD guideline study, GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Objective of study:
absorption
distribution
excretion
Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 417 (Toxicokinetics)
Version / remarks:
adopted April 4, 1984
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Radiolabelling:
yes

Test animals

Species:
rat
Strain:
Wistar
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River, Sulzfeld
- Age at study initiation: 7 weeks
- Weight at study initiation: 293-319 g
- Fasting period before study: Animals receiving radiolabelled test material were fasted for approximately 18 hours prior to and for approximately four hours after the adminisfration
- Housing: Macrolon plastic cages (type M III)
- Individual metabolism cages: yes
- Diet: animals had free access to standard pelleted laboratory animal diet
- Water: tap water ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-25
- Humidity (%): 40-80
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
VEHICLE
- Concentration in vehicle: 10 and 200 mg/mL
- Amount of vehicle (if gavage): 5 ml/kg bw

HOMOGENEITY AND STABILITY OF TEST MATERIAL:
Immediately after preparation, and prior to dose administration, the homogeneity and radioactivity concentration of each formulation was verified by radio analysis. For this purpose, a weighed aliquot of 10 µL was taken from the top, middle and bottom of the mixture and analysed by liquid scintillation counting (LSC) using Ultima Gold (Packard) scintillation cocktail.

The 4-hour stability of the test substance in the vehicle at ambient temperature was determined at NOTOX prior to the start of dosing for both concentrations. For this purpose, immediately after preparation of the dose suspension a weighed aliquot of 10 µL was taken from the top, middle and bottom of the mixture and analysed by LSC using Ultima Gold (Packard) scintillation cocktail. Another aliquot of the dose suspension was diluted in acetone prior to TLC analysis. The same analytical procedures were applied to both dose suspensions after storage at ambient temperature on a magnetic stirring device for 4 hours. Hence [ring methyls-14C]-test substance was considered stable in corn oil under the conditions of testing for a period of 4 hours.
Duration and frequency of treatment / exposure:
All animals received a single dose via oral gavage.
Doses / concentrations
Remarks:
Doses / Concentrations:
The nominal dose levels of the test item were 50 and 1000 mg/kg bw, and the nominal radioactivity contained in each dose was approximately 3 MBq.
No. of animals per sex per dose:
4 male rats per dose
Control animals:
no
Details on dosing and sampling:
PHARMACOKINETIC STUDY
- Tissues and body fluids sampled: urine, cage washes, faeces, volatiles, blood, volatiles, plasma and tissues: Liver, kidneys, spleen, abdominal fat, muscle (left hind leg), G.I. tract, gonads (testes, seminal vesicles, prostate), bone (left femur), thymus, skin, and carcass. The weight of each tissue and blood sample was recorded at the time it was harvested.
- Time and frequency of sampling:
urin and faeces: 0-24, 24-48,48-72, and 72-96 hours after administration;
volatiles: 0-8,8-24, 24-36, and 36-48 h after the administration.
all others: 96 h after administration
Statistics:
The mean and standard deviation were used to characterise the data, where appropriate (i.e., radioactivity measurement, concentrations, etc.). Concentrations of radioactivity in blood, plasma and tissues were calculated as mg equivalents of test substance/kg of sample. The total amounts of radioactivity in tissue and excreta samples were calculated as a percentage of the administered radioactivity and a 14C mass balance is presented. Individual excretion half-lives (t ½)) were calculated by linear regression of time versus log concentration curves for urine and faeces.

Results and discussion

Main ADME resultsopen allclose all
Type:
absorption
Results:
not specified
Type:
distribution
Results:
fat > thymus > liver > kidney > skin, gastrointestinal tract, carcass > blood
Type:
excretion
Results:
Mainly via faeces and in a lower extend via urine and negligibly via expired air.
Type:
other: bioaccumulation
Results:
Low tissue levels indicate extremely low bioaccumulation.

Toxicokinetic / pharmacokinetic studies

Details on absorption:
Study design does not provide details experimental details on absorption.
Details on distribution in tissues:
In the tissues and organs examined at 96 h postdose, the highest mean tissue concentration was observed in the fat (2.42 and 116 mg/kg tissue at low and high dose respectively), followed by thymus, liver and kidney (overall range of means 1.39-1.88 and 13.6-25.9 mg/kg tissue for low and high dose respectively), and, at the high dose, by skin, gastrointestinal tract and carcass (overall range of means 11.9-17.4 mg/kg tissue). Tissue levels in the blood at 96 h postdose were 0.06 and 0.6 mg/kg tissue for the low and high dose respectively. The retention of the administered radiolabel was very limited. Generally, the organs and tissues examined contained less than 0.01 % of the dose, except the liver (< 0.15 %), and the kidney and gastrointestinal tract (< 0.03%). There were no significant differences in the pattern of distribution between the high and low dose.
Details on excretion:
Following the 50 and 1000 mg doses, respectively, 9 and 6% of the administered radioactivity was recovered from urine within 96 hours after administration. The majority of radiolabel (92-93 %) was excreted via the faeces, predominantly during the first 24 hours post dose. Excretion via the faeces, however, does not
necessarily mean that the compound was not absorbed. Excretion of radioactivity via expired air was negligible (< 0.03% of the dose). Cumulative excretion of total radioactivity after oral administration of [ring methyls-14C]-test substance was virtually complete within 96 hours after dosing.
Toxicokinetic parametersopen allclose all
Test no.:
#1
Toxicokinetic parameters:
other: excretion half-life urine: 11.84 h (mean value from 4 rats; administration of 50 mg radiolabelled test substance)
Test no.:
#1
Toxicokinetic parameters:
other: excretion half-life faeces: 9.14 h (mean value from 4 rats; administration of 50 mg radiolabelled test substance)
Test no.:
#1
Toxicokinetic parameters:
other: excretion half-life urine: 14.55 h (mean value from 4 rats; administration of 1000 mg radiolabelled test substance)
Test no.:
#1
Toxicokinetic parameters:
other: excretion half-life faeces: 8.61 h (mean value from 4 rats; administration of 1000 mg radiolabelled test substance)

Metabolite characterisation studies

Metabolites identified:
not measured

Applicant's summary and conclusion