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Administrative data

Description of key information

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
short-term repeated dose toxicity: oral
combined repeated dose and reproduction / developmental screening
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
reference to same study
according to guideline
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Version / remarks:
of 1996
GLP compliance:
yes (incl. QA statement)
Limit test:
Details on test animals or test system and environmental conditions:
- Sprague Dawley rats, strain: Crl:CD(SD) with appropriate range of bodyweight at study start.
- Source: Charles River (UK) Ltd.
- Age at treatment start: 61-68 days.
- Weight at treatment start: Males: minimum 332 g, maximum 397 g,
Females: minimum 210 g, maximum 255 g.
- Housing Inside a barriered rodent facility:
all animals pre-pairing + toxicity subgroups: In groups up to 5 by sex in solid floor polycarbonate cages.
during pairing (1 male+1 female/cage): In RB3 modified polypropylene cages with stainless steel grid-floor over absorbent paper-lined trays.
males after pairing: In groups of up to 5 in solid floor polycarbonate cages.
females during gestation and lactation: Females housed individually (+litter) in solid floor polycarbonate cages.
- Bedding material (in solid floor cages): Wood based bedding.
- Cage enrichment: Aspen chew block + plastic shelter (except during pairing or post gestation day 20).
- Diet (ad libitum): Standard rodent diet (SDS VRF1 Certified) without antibiotic, chemotherapeutic or prophylactic agent.
- Fasting (diet withheld): Main phase males and Toxicity phase females overnight before blood sampling for clinical pathology.
- Water (ad libitum): Potable drinking water from the public supply.
- Acclimation period: 5 days before treatment start, under laboratory conditions.

Routine analysis of the batch of diet used and water, chew blocks and bedding material did not provide evidence of contamination that might have prejudiced the study.

- Duration of test, males & toxicity phase females: Five weeks
Duration of test, main phase females (i.e. reproductive subgroup): From 14 days prior to pairing to day 6 of lactation.
Duration of test, offspring: From birth to day 6 of lactation.


Air conditioned room kept at positve pressure without re-circulation of the filtered fresh air supplied to the room.
Controlled environment, environmental conditions were set at:
- Temperature (°C): 21 ± 2°C
- Relative Humidity (%): 40 to 70%
- Photoperiod (artificial lighting): 12 hrs day / 12 hrs night
Deviations from the target ranges for temperature and relative humidity were not evident.
Route of administration:
oral: gavage
corn oil
Details on oral exposure:
- Concentration in vehicle: The concentration of the test material in vehicle was 20, 60, and 200 mg/ml.
- Amount (dose volume by gavage): 5 mL/kg bw/day..
Actual dose volumes were calculated at about weekly or shorter intervals accounting for the latest body weight. Litter animals were not dosed.
Analytical verification of doses or concentrations:
Details on analytical verification of doses or concentrations:
- Chemical analysis of test material formulations by high performance liquid chromatography coupled with a mass spectrometer (HPLC-MS/MS).
- Concentrations (verified at first and last treatment week) of the test material formulations were confirmed at each dose level.
- Chemical analysis confirmed that the mean concentrations of WS405777 in prepared formulations were 100% to 113% of the corresponding
nominal concentration, thus confirming accuracy of formulation.
Duration of treatment / exposure:
- Treatment period, males & toxicity phase females: Daily, for five consecutive weeks, in males commencing 14 days prior to pairing
- Treatment period, main phase females (i.e. reproductive subgroup): 43 to 46 days (from 14 days prior to pairing to day 6 of lactation)
- Offspring were not dosed
Frequency of treatment:
Daily, 7 days/week (during parturition, dosing omitted as appropriate)
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:
Toxicity phase animals: */ 5 females
Main phase animals (i.e. reproductive subgroups): 10 males / 10 females
*Explanatory note by the notifier:
Examinations assigned to the toxicity phase females to meet the requirements of a 28-day repeat dose oral toxicity study were also assigned to 5 main phase males per dose group. Therefore, these 5 main phase males per dose group are called also "toxicity subgroup" in the present robust study summary for clarification. After pairing with main phase females, all males were killed at the same time (Week 6).
Control animals:
yes, concurrent vehicle
Details on study design:
This study was conducted to examine both repeated dose toxicity and  reproductive/developmental toxicity as an OECD screening combined study
(OECD 422 test guideline).  Therefore, animals initially entering the study were divided into toxicity subgroup animals (toxicity phase) and reproductive subgroup animals (main phase), whereby 5 of the 10 F0 males (used for pairing) per dose group formed the toxicity male subgroups.

Dose selection was based on the results of a 7-day preliminary oral toxicity study in the rat in which dose levels of 100, 300 or 1000 mg/kg/day did not have any overt treatment-related effects on young adult animals (females nulliparous and non-pregnant). Accordingly the same dose levels were used in the present OECD 422 combined repeat dose toxicity and reprotoxic/develpmental toxicity screening study.
Positive control:
Not included in the study.
Observations and examinations performed and frequency:
Clinical observations performed and frequency:
- Clinical signs : At least twice a day (before and after administration)
- Detailed physical examination
and arena observations: Before treatment start and at least once a treatment week.
- Functional Observation Battery:* During treatment week 5 (before dosing) on all toxicity subgroup animals (5 males + 5 females/group).
- Body weight, all males: Weekly throughout the study.
Body weight, Toxicity Females: Weekly throughout the study.
- Food consumption, all males: Weekly for pre-pairing period and for the period after mating.
Food cons., Toxicity Females: About weekly throughout the study.

* FOB including sensory reactivity tests (approach, touch, auditory startle reflex, tail pinching), grip strength and motor activity.

Hematological examinations (only for toxicity subgroup animals) during treatment week 5 at least one day after functional observation battery:
Red blood cell count, reticulocyte count, white blood cell count, platelet count, hemoglobin concentration, hematocrit value, differential leukocyte counts, protrombin time, activated partial thromboplastin time, mean cell volume, mean cell hemoglobin, mean cell hemoglobin concentration.

Blood (plasma) chemical examinations (only for toxicity subgroup animals) during treatment week 5 at least one day after functional observation battery:
Total protein, albumin, A/G ratio, urea, creatinine, glucose, total cholesterol, total bilirubin, bile acids, sodium, potassium, chloride,
calcium, inorganic phosphorus, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase.
Sacrifice and pathology:
GROSS PATHOLOGY: Yes, see below
WEIGHING OF ORGANS: Yes, see below
HISTOPATHOLOGY: Yes, see below

Terminal sacrifice
- all males and toxicity subgr. females: Killed in Week 6, after completion of the Treatment Week 5 investigations.

Gross pathology:: Full macroscopic examination with tissue collection.

Organ Weights:
- main phase and tox. subgr. adults: Adrenals, brain, epididymides, heart, kidneys, liver, ovaries, prostate, seminal vesicles & coagulation
gland, spleen, testes, thymus, uterus with cervix & oviducts.

- toxicity subgroups: The following organs were microscopically observed for the control and 1000 mg/kg bw/day groups:
Brain, eyes, pituitary gland, thyroid with parathyroids, heart, thymus, liver, spleen, adrenals
kidneys, testes, epididymides, ovaries, lung, trachea, esophagus, stomach, duodenum, jejunum, ileum, caecum, colon, rectum, Peyer's patch, lymph node (axillary, mesenteric), urinary bladder, uterus (with cervix &
oviducts), vagina, spinal cord, sciatic nerve, skeletal muscle, skin with mammary glands, sternum with marrow,
seminal vesicle & coagulation gland, prostate. In addition, any gross lesions from all dose groups
were examined by light microscopy.
Other examinations:
Reproductive and developmental toxicity parameters (addressed in separate endpoints).
Grip strength, motor activity, bodyweight, food consumption, organ weight, blood chemistry and haematology data were statistically analysed by adoption of the following sequence of tests:

- Parametric analysis, if Bartlett's test for variance homogeneity was not significant at the 1% level.
F1 approximate test for monotonicity of dose-response. If this F1 test was not significant at the 1% level, Williams' test for a monotonic trend was applied.
If this F1 test was significant, suggesting that the dose-response was not monotone , the Dunnett's test was performed instead.

- Non-parametric analysis, if Bartlett's test was still significant at the 1% level following logarithmic and square-root transformations.
H1 approximate test for monotonicity of dose-response. If this H1 test was not significant at the 1% level, Shirley's test for a monotonic trend was applied.

-For grip strength, motor activity, and clinical pathology data,
if 75% of the data (across all groups) were the same value, pairwise comparison of each dose group against the control by Fisher’s Exact tests.

-For organ weight data, covariance analysis using terminal bodyweight as covariate (Angervall & Carlstrom, 1963).

For statistical references, see next field.
Clinical signs:
no effects observed
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
no effects observed
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:
no effects observed
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed
Key result
Dose descriptor:
Effect level:
>= 1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: NOAEL = highest dose tested.
Key result
Critical effects observed:
Executive summary:

Administration of WS405777 to rats at dose levels of 100, 300 and 1000 mg/kg/day was well tolerated with no effects that could be attributed to treatment. The NOAEL was derived at the highest dose, i.e. 1000 mg/kg/day.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Study duration:

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Justification for classification or non-classification

In the OECD 422 study the NOAEL was derived at the highest dose of 1000 mg/kg/day for systemic toxicity in adult male and female rats after five weeks of oral exposure to WS405777. This does not necessitate any classification regarding repeated exposure according to European classification rules [Regulation (EC) 1272/2008].