Registration Dossier

Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1991

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: T44-03:Guidelines for Reproduction Studies for Safety Evaluation of Drugs for Human Use(FDA:1966)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): MMB
- Physical state: clear liquid
- Analytical purity: 100%
- Receiced on (date): 10 august 1990
- Lot/batch No.: 023849
- Storage condition of test material: 4°C (refrigerated)
- Other:

Test animals

Species:
rat
Strain:
Crj: CD(SD)
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Inc.
- Age at study initiation: 72 days (birthday: 20 august 1990; female); 66 days (birthday: 18 feburary 1990; male)
- Weight at study initiation: 196 to 228 g (after day of arrival; female); 242 to 288 g (after day of arrival; male)
- Housing: 1 per stainless steel cage
- Diet (e.g. ad libitum): ad libitum ( certified rodent chow; Ralston purina)
- Water (e.g. ad libitum): ad libitum (reverse osmosis membrane)


ENVIRONMENTAL CONDITIONS
- Temperature: 70 to 78 °F
- Humidity (%): 40 to 70 %
- Air changes (per hr): 10/hr
- Photoperiod (hrs dark / hrs light): 12 h dark/12 h light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Solutions of the test article in deionized water were prepared daily during the study. The following concentrations of 3-methoxy-3-methyl-butan-1-ol were preparted: 0, 25, 50, 200 mg/mL

DIET PREPARATION
no details given

VEHICLE
- Concentration in vehicle: 0, 25, 50, 200 mg/mL
- Amount of vehicle (if gavage): 10 ml/kg
- Lot/batch no. (if required): 023849
- Purity: 100%
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
target concentrations: 12.5; 200 mg/mL
measured average concentrations: 12.33; 196.8 mg/mL
GC (Shimadzu, FID detector); (conducted at Lancaster Laboratories Inc.)
Details on mating procedure:
- Impregnation procedure:
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: female rats with spermatozoa observed in a vaginal lavage or a copulatory plug observed in situ were considered to be at day 0 of presumed gestation and assigned to individual housing
- All females rats that did not have a confirmed mating date, as well as all female rats that mated but were not assigned to the study, were placed in the general population of the test facility.
Duration of treatment / exposure:
day 6 through 15 of gestation
Frequency of treatment:
once a day
Duration of test:
15 days from 6 to 20 days of gestation
No. of animals per sex per dose:
25
Control animals:
yes, concurrent vehicle
Details on study design:
Sex: female
Duration of test: for 15 days from 6 to 20 days of gestation

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily for test duration

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: day 0 and on days 6 through 20 of presumed gestation

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes; day 0 and on days 6 through 20 of presumed gestation

POST-MORTEM EXAMINATIONS: Yes /
- Sacrifice on gestation day #20
- Organs examined: laparaohysterectomic examination and necropsy

OTHER:
half of the foetuses from 0 and 2000 mg/kg bw/day groups were examined for soft tissue abnormalities
half of the foetuses from all groups were examined for skeletal abnormalities
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
Statistics:
Dunnet (1955), A multiple comparison procedure for comparing several treatments with a control
Snedecor (1967), variance test for homogeneity of the binomial distribution
Siegel (1956), nonparametric statitistics for the behavioral sciences
Dunn (1964), multiple comparisons using rank sums
Kruskal-Wallis test

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
No rats died during the conduct of this study
Decreased mortor activity, excess salivation, ataxia, muscle flaccidity and loss of righting reflex were observed in the 2000 mg/kgbw/day group.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
< 250 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
maternal abnormalities
Dose descriptor:
NOAEL
Effect level:
500 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
maternal abnormalities

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
The 2000 mg/kgbw/day group reduced fetal body weight. No other Caesarean-sectioning or litter observations were attributable to the test material. Malformations and variations: The test material did not cause fetal malformations. The 2000 mg/kgbw/day group had significant increases in the litter and fetal incidences of variations in skeletal ossification of the ribs, sternum and pelvis.

Effect levels (fetuses)

open allclose all
Dose descriptor:
LOAEL
Effect level:
2 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
fetal/pup body weight changes
Dose descriptor:
LOAEL
Effect level:
2 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
changes in litter size and weights

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables


NOEL for pregnant females: Less than 250 mg/kgbw/day
NOEL for development of fetuses: 500 mg/kgbw/day
  
Clinical signs: Decreased mortor activity, excess salivation, ataxia, muscle flaccidity and loss of righting reflex were observed in the 2000 mg/kgbw/day group.
Body weights: Decreases of body weight gains in pregnant females of 250, 500 and 2000 mg/kgbw/day.
Food consumption: The 250, 500 and 2000 mg/kgbw/day groups had significant reductions in absolute (g/day) and
relative(g/kg/day) maternal feed consumption values for the entire dosage period.
Necropsy: No gross lesions were caused by the test material.
Fetal parameters: The 2000 mg/kgbw/day group reduced fetal body weight. No other Caesarean-sectioning or litter observations were attributable to the test material.
Malformations and variations: The test material did not cause fetal malformations. The 2000 mg/kgbw/day group had
significant increases in the litter and fetal incidences of variations in skeletal ossification of the ribs, sternum and pelvis.

Applicant's summary and conclusion

Conclusions:
A well reported study conducted according to generally accepted scientific standards and in accordance with GLP reported maternal toxicity (increased incidences of clinical observations, and decreases in body weight gain and food consumption) at 500 and 2000 mg/kg bw/day. The occurrence of maternal toxicity was accompanied by fetal toxicity (reduced fetal body weight and significant increases in the litter and fetal incidences of variations in skeletal ossification of the ribs, sternum and pelvis at 2000 mg/kg bw/day). No significant maternal or developmental effects were observed at 250 and 500 mg/kg bw/day, respectively. The maternal NOEL was 250 mg/kg bw/day and developmental NOAEL was 500 mg/kg bw/day.