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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:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Limit test:
no

Test material

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals or test system and environmental conditions:
TEST ANIMALS Sprague Dawley rats, strain Crl:CD(SD)
- Source: Charles River (UK) Ltd.
- Age at study initiation: approx. 70 days (Day 0 of gestation)
- Weight at study initiation: 227-278 g
- Fasting period before study: none
- Housing: one cage per animal during gestation
- Diet (e.g. ad libitum): ad libitum (pelleted diet)
- Water (e.g. ad libitum): ad libitum (tap water)
- Acclimation period: five days before commencement of pairing

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23°C
- Humidity (%): 40-70%
- Photoperiod (hrs dark / hrs light): 12 h light, 12 h dark

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Justification for use and choice of vehicle (if other than water): corn oil allows good dispersion of test substance, experience from other gavage studies
- Concentration in vehicle: 50, 150, 500 mg/ml
- Amount of vehicle (if gavage): 2 ml/kg body weight
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
- Chemical analysis of test material formulations by high performance liquid chromatography (HPLC/UV) using an external standard technique.
- Concentrations (verified for first and last preparation) of the test material formulations were confirmed at each dose level.
- Chemical analysis confirmed that the prepared formulations were within 4% of the corresponding nominal concentration.
Details on mating procedure:
- M/F ratio per cage: 1 : 1 with identified stock males
- Length of cohabitation: until positive evidence of mating was detected
- Proof of pregnancy: ejected copulation plugs and vaginal smears were checked for presence of sperm; when positive then referred to as day 0 of pregnancy
Duration of treatment / exposure:
females were treated from Day 6 to Day 19 (inclusive)
Frequency of treatment:
once daily
Duration of test:
animals were killed on Day 20 after mating
Doses / concentrationsopen allclose all
Dose / conc.:
100 mg/kg bw/day (actual dose received)
Dose / conc.:
300 mg/kg bw/day (actual dose received)
Dose / conc.:
1 000 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
20 animals per group
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on result of reproduction toxicity screening study

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: once daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: Days 0, 3 and 6-20 after mating

FOOD CONSUMPTION AND COMPOUND INTAKE : Yes
- Food consumption for each animal determined for days: 0-2, 3-5, 6-9, 10-13, 14-17 and 18-19

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- Organs examined: detailed necropsy and macroscopic examination of tissues
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
- Number of fetuses: 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:
The analyses were carried out using the individual animal as the basic experimental unit. For litter/fetal findings the litter was taken as the treated unit and the basis for statistical analysis and biological significance was assessed with relevance to the severity of the anomaly and the incidence of the finding within the background control population.
The following data types were analysed at each timepoint separately:
Body weight, using absolute values and gains over appropriate study periods
Gravid uterine weight and adjusted body weight
Food consumption, over appropriate study periods
Litter size and survival indices
Fetal, placental and litter weight

A sequence of statistical tests was used for body weight, gravid uterine weight, food consumption, corpora lutea, implantations, live young, fetal, placental and litter weight data.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
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:
not examined
Gross pathological findings:
not examined
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined

Maternal developmental toxicity

Number of abortions:
no effects observed
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
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): not examined
Changes in number of pregnant:
no effects observed

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (actual dose received)
Basis for effect level:
other: no effects observed in maternal animals

Maternal abnormalities

Key result
Abnormalities:
no effects observed

Results (fetuses)

Fetal body weight changes:
no effects observed
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): 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:
not examined
External malformations:
no effects observed
Skeletal malformations:
no effects observed
Visceral malformations:
no effects observed
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The incidence of major and minor visceral and skeletal abnormalities and skeletal variants showed no relationship to treatment.

Across all treated groups there was a slightly higher incidence of incompletely ossified hyoid and 13/14 14/14 short supernumerary ribs compared to concurrent control but was within Historical Control Data (HCD) (see attachment "historical control data").

At 1000 mg/kg/day there was also a slightly higher incidence of incompletely ossified sacrocaudal vertebrae compared to concurrent control but again this was within HCD.

These findings are therefore considered to be unrelated and incidental, showing no clear treatment relationship.

Effect levels (fetuses)

Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (actual dose received)
Basis for effect level:
other: teratogenicity, embryotoxicity, fetotoxicity

Fetal abnormalities

Key result
Abnormalities:
no effects observed

Overall developmental toxicity

Key result
Developmental effects observed:
no

Any other information on results incl. tables

There was no effect of WS400128 on body weight and body weight change as well as food consumption during gestation (Tables 2, 3, 4 in the attachment "result tables from OECD 414 study with WS400128).

There was no effect of WS400128 on implantations, early or late resorptions, live young or sex ratio (Table 5 in the attachment "result tables from OECD 414 study with WS400128).

There was no effect of treatment on placental weight or litter weight (Table 6 in the attachment "result tables from OECD 414 study with WS400128).

The incidence of major and minor visceral and skeletal abnomalities and skeletal variants showed no relationship to treatment (Tables 7, 8, 9 in the attachment "result tables from OECD 414 study with WS400128).

Applicant's summary and conclusion

Conclusions:
Based on the results of this study the No Observed Adverse Effect Level for maternal toxicity, embryo-fetal survival, growth and development was considered to be at least 1000 mg/kg body weight/day.