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Developmental toxicity / teratogenicity

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developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 December 2018 - 06 January 2019
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report

Materials and methods

Test guideline
no guideline required
Principles of method if other than guideline:
The study was not designed to meet any particular regulatory requirement. No claim for compliance with Good Laboratory Practice was made, although the work performed generally followed Good Laboratory Practice principles.
GLP compliance:
Not Required, Preliminary study used to inform main testing.
Limit test:

Test material

Constituent 1
Test material form:
Details on test material:
Batch number: AAF1453400
Purity: UVCB
Specific details on test material used for the study:
Batch number: AAF1453400
Purity: UVCB

Test animals

New Zealand White
Details on test animals or test system and environmental conditions:
Strain/Species: New Zealand White rabbit.
Supplier: Envigo RMS.
Number of animals ordered: 28 time mated females (delivered as two batches of 14 females).
Day of delivery: Gestation Day 1.
Duration of acclimatization: Five days from arrival on GD1 to start of treatment on GD6.
Age of the animals at the start of the study (Day 1 of gestation): 18 to 22 weeks old
Weight range of the animals at the start of the study (Day 1 of gestation): 2.50 to 4.44 kg

Temperature and relative humidity: Monitored and maintained within the range of 15-21°C and 45-70%.
Air changes (per hr): Filtered fresh air which was passed to atmosphere and not recirculated.
Photoperiod (hrs dark / hrs light): Artificial lighting, 14 hours light : 10 hours dark.

Administration / exposure

Route of administration:
oral: gavage
Details on exposure:

Diet: Teklad 2930 Diet. The diet contained no added antibiotic or other chemotherapeutic or prophylactic agent.
Availability: Restricted 200 g/animal/day.
In addition to this diet, a small supplement of autoclaved hay was given on a daily basis to promote gastric motility and a small amount (approximately 20 g) of chopped fresh vegetables was offered twice weekly. Consumption of hay was monitored qualitatively but not quantitatively.

- Choice of vehicle (if other than water): Aqueous 1% w/v methylcellulose
- Amount of vehicle (if gavage): 5 mL/kg
Analytical verification of doses or concentrations:
Details on analytical verification of doses or concentrations:
none specified
Details on mating procedure:
Natural mating with New Zealand white bucks of established fertility at the supplier’s facility. Males and females not closely related. After mating each female injected intravenously with 25 i.u. luteinising hormone.
Duration of treatment / exposure:
Females were treated from Day 6 to Day 28 (inclusive) after mating.
Frequency of treatment:
Once daily at approximately the same time each day.
Duration of test:
28 days
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
90 mg/kg bw/day (nominal)
Dose / conc.:
180 mg/kg bw/day (nominal)
Dose / conc.:
375 mg/kg bw/day (nominal)
No. of animals per sex per dose:
7 females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: A previous pilot study
- Rationale for animal assignment (if not random): Random


Maternal examinations:
- Time schedule: Daily

- Time schedule: Animals were inspected visually at least twice daily

- Time schedule for examinations: The weight of each adult was recorded on the day of arrival (Day 1 after mating) and on Days 3, 6-29 after mating.

The weight of food supplied to each animal, that remaining and an estimate of any spilled was recorded daily from Day 2 after mating.


- Animals surviving until the end of the scheduled study period were killed on Day 29 after mating.
Ovaries and uterine content:
For females surviving to term, the following was recorded:
Uterus - Gravid uterine weight (including cervix and ovaries).

The following were recorded for all animals:
For each ovary/uterine horn: Number of Corpora lutea, Implantation sites, Intrauterine deaths (classified as early or late), Fetuses (live and dead).
Apparently non-pregnant animals and for apparently empty uterine horns: The absence or number of uterine implantation sites was confirmed.
Fetal examinations:
All fetuses and placentae were dissected from the uterus and weighed individually. Fetuses were individually identified within the litter, using a coding system based on their position in the uterus. Each placenta and fetus was externally examined and an internal examination of the neck and the contents of the thoracic and abdominal cavities of each fetus was performed and any abnormalities were recorded, sampled as appropriate and retained in appropriate fixative. The sex of each fetus was recorded. Grossly normal fetuses were discarded.
Where appropriate, group mean values, each with standard deviation (SD), were calculated from individual data.
Not specified
Historical control data:
Not specified

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
no effects observed
no mortality observed
Body weight and weight changes:
no effects observed
Description (incidence and severity):
At 375 mg/kg/day mean bodyweight loss of 0.05 kg was recorded during Days 6-10 of gestation compared with a mean weight gain of 0.07 kg in controls; this resulted in a lower than control overall bodyweight gain.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
There was no effect of treatment on food consumption following treatment of with 90 or 180 mg/kg/day; reduced food intake was evident in animals treated at 375 mg/kg/day during the second week of treatment (GD12-16). Overall food consumption for animals at 375 mg/kg/day was 87% of the control group.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not examined

Maternal developmental toxicity

Number of abortions:
not examined
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Changes in pregnancy duration:
not examined
Changes in number of pregnant:
not examined
Other effects:
no effects observed

Effect levels (maternal animals)

Key result
Dose descriptor:
dose level: suitable for main study
Effect level:
ca. 375 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
body weight and weight gain
clinical signs
food consumption and compound intake
gross pathology
organ weights and organ / body weight ratios
pre and post implantation loss
total litter losses by resorption

Maternal abnormalities

Key result
no effects observed

Results (fetuses)

Fetal body weight changes:
no effects observed
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
no effects observed
External malformations:
no effects observed
Skeletal malformations:
not examined
Visceral malformations:
not examined
Other effects:
not examined
Details on embryotoxic / teratogenic effects:
Litter data as assessed by the number of implantations, resorptions, live young, sex ratio and the extent of the pre- and post-implantation loss was unaffected by maternal treatment. Macropathological examination of the fetuses showed no treatment related abnormality.
There was no effect of treatment on placental and litter weights; overall fetal weights from Dams treated at 375 mg/kg/day were slightly less than control, however, this was considered to be due to the slightly larger litter size in these animals.

Effect levels (fetuses)

Key result
Dose descriptor:
dose level: for main study
Effect level:
ca. 375 mg/kg bw/day (nominal)
Based on:
test mat.
not specified
Basis for effect level:
reduction in number of live offspring
changes in sex ratio
fetal/pup body weight changes
changes in litter size and weights
changes in postnatal survival
external malformations

Fetal abnormalities

Key result
no effects observed

Overall developmental toxicity

Key result
Developmental effects observed:
Lowest effective dose / conc.:
375 mg/kg bw/day (nominal)
Treatment related:

Applicant's summary and conclusion

Based on the findings in this study a dose level of 375 mg/kg/day was considered suitable for use as the high dose level on the forthcoming main embryo-fetal development study.