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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
29 Feb - 28 Mar 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Comparable to guideline study with acceptable restrictions. The test substance was only administered during organogenesis and not through the entire period of gestation to the day before caesarean section. Body weights were not determined in 3-day intervals during treatment period.

Data source

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

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
test substance was only administered during organogenesis and not through the entire period of gestation to the day before caesarean section; body weights were not determined in 3-day intervals during treatment period
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
other: Sprague Dawley, CD
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River, Wiga GmbH, Sulzfeld, Germany
- Age at study initiation: 8 weeks
- Weight at study initiation: 203 g
- Housing: individually in Makrolon Type M3 cages (EBECO, Castrop-Rauxel, Germany) with standard softwood bedding (ARWI-Center, Düsseldorf, Germany)
- Diet: pelleted Atromin Maintenance Diet 1324 (ALTROMIN GmbH, Lage, Germany), ad libitum
- Water: community tap water (Düsseldorf, Germany), ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23
- Humidity (%): 40-66
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: the test substance was prepared daily before administration by dissolving appropriate amounts in water.

VEHICLE
- Concentration in vehicle: 1, 3 and 10% (v/v)
- Amount of vehicle (if gavage): 10 mL/kg bw
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The formulations of test substance were analysed once in a previous study by High Performance liquid chromatography (HPLC). In this study, the determined analytical concentrations of 0.94, 2.88 and 9.23% verified the nominal concentrations of 1, 3 and 10% of the test substance in solution.
Details on mating procedure:
- Impregnation procedure: purchased timed pregnant
Duration of treatment / exposure:
(P) Females: Day 6-15 of gestation (organogenesis period)
Frequency of treatment:
once daily in the morning
Duration of test:
20 days
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 100, 300, 1000 mg/kg bw
Basis:
nominal conc.
No. of animals per sex per dose:
24 P females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on the results of previous toxicological examinations

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: animals were checked at least twice daily (working days) for clinical signs and mortality.

BODY WEIGHT: Yes
- Time schedule for examinations: body weights were determined on Day 0, 6, 16 and 20

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: all maternal organs with emphasis on uterus
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
- Head examinations: No
Statistics:
Mean values and standard deviations were calculated. Statistical analyses at significance levels of 5% and 1% were performed on the following parameters and using the following statistical tests:
- Steel test: implantation sites, embryonic and foetal resorptions, live and dead foetuses
- Fishers exact test (Bonferroni-Holm-corrected): pre- and post-implantation loss, total embryonic deaths, total and malformed foetuses, skeletal parameters
- Dunnett-test based on pooled variance: weights of live foetuses, placenta and uteri
Indices:
Percentage of implantation sites: (no. of implantations / no. of corpora lutea) * 100

Percentage of pre-implantation loss: [(no. of corpora lutea - no. of implantations) / no. of corpora lutea] * 100

Percentage of post-implantation loss: [(no. of implantations - no. of live foetuses) / no. of implantations] * 100

Percentage of embryonic resorptions: (no. of embryonic resorptions / no. of implantations) * 100

Percentage of foetal resorptions: (no. of foetal resorptions / no. of implantations) * 100

Percentage of total foetuses: (no. of total foetuses / no. of implantations) * 100

Percentage of malformed foetuses: (no. of malformed foetuses / no. of total foetuses) * 100

Percentage of male foetuses: (no. of male foetuses / total no. of live foetuses) * 100

Percentage of female foetuses: (no. of female foetuses / total no. of live foetuses) * 100

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Details on maternal toxic effects:
MORTALITY:
No deaths occurred in dams receiving the vehicle or the test substance at doses of 300 mg/kg bw/d. Due to an application error, test substance-unrelated mortalities were found on Day 11 and 13 each in one animal of the 100 and 1000 mg/kg bw/d test group.

CLINICAL SIGNS:
No substance-related symptoms were observed at any dose level during the study. The animal of the 100 mg/kg bw/d test group found dead on Day 11 showed impeded respiration, lethargy, and a decrease in body weight on Day 10. One animals of the high dose group (1000 mg/kg bw/d) showed impeded respiration on Day 15 and 16 and lethargy on Day 16. However, these findings were not related to treatment.

BODY WEIGHTS:
Maternal body weights were not affected by treatment.

REPRODUCTION DATA:
No substance-related effects on reproduction data were noted compared to controls.

NECROPSY:
At scheduled necropsy, no macroscopic changes were observed between treated and control animals. Incidental findings in two animals either comprised white nodules in the left inguinal region or haematoma in the region of larynx.

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
EMBRYOTOXICITY/FETOTOXICITY:
No substance-related differences in pre-and post-implantation loss, mean figures of resorptions, embryonic deaths and total foetuses were observed in treated animals compared to controls.

BODY WEIGHTS:
The weight of live foetuses exhibited not significant differences on a litter or individual basis.

PLACENTA AND UTERUS WEIGHT:
The weight of placenta and uteri including content showed no significant differences between treated and control animals.

SEX RATIOS:
The foetal sex ratio was comparable in all test groups.

EXTERNAL OBSERVATIONS:
No abnormal findings were observed that were considered to be related to treatment. Incidental findings comprised the occurrence of only one placenta for two foetuses in the control group and one foetus with hydrops in the high dose group (1000 mg/kg bw/d).

VISCERAL OBSERVATIONS:
The main figures of visceral variations (hydronephrosis, dilated and waved ureters) were similar compared to controls and not considered to be related to treatment. All other findings except for situs inversus total in the high dose group and enlarged parenchymous organs in the controls were considered to be incidental.

SKELETAL EXAMINATION:
The figures of skeletal variations (absent or malformed cervical vertebrae arches, luxation and malposition of the mandible) in all test groups were within the range of normal spontaneous findings. Retarded ossification was found in all treatment groups and was similar to the level of skeletal ossification in the control group. The isolated statistically significant difference in the figure “14 ribs short/rudimentary bilateral” in the high dose group (100 mg/kg bw/d) was considered to be incidental and not related to treatment, since no dose-response relationship was apparent.

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no treatment related

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
According to the study described, the test substance does not reveal any embryotoxic or teratogenic potential.