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Repeated dose toxicity: oral

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short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1989-Mar-03 to 1989-Apr-14
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: OECD guideline study with GLP, acceptable with restriction (analytical purity of the test substance not reported).

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity in Rodents)
analytical purity of the test substance not reported
GLP compliance:
(Safepharm Laboratories Limited, UK)
Limit test:

Test material

Details on test material:
- Name of test material: N-Vinylcaprolactam

Test animals

Details on test animals and environmental conditions:
- Source: Interfauna (U.K.) Limited, Cambridgeshire
- Weight at study initiation: males (147-188 g) and females (152-184 g)
- Housing: 5 per sex per cage
- Diet (e.g. ad libitum): A pelleted diet (SQC Rat and Mouse Diet No. 1 Expanded, Special Diet Services
Limited, Witham, Essex, U.K.)
- Water: ad libitum

- Temperature (°C): 20-24
- Humidity (%): 35-62
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
arachis oil
Details on oral exposure:
The test material was liquified by warming in a water bath at 37°C, added to arachis oil at the appropriate concentrations and shaken thoroughly. Stability of the test material formulations was determined by Safepharm Analytical Laboratory prior to the start of the study and found to be stable for at least nine days. Formulations were therefore prepared weekly and stored at 4°C in the dark.

- Concentration in vehicle: 0, 25, 125 and 250 mg/mL
- Amount of vehicle: 2 mL/kg bw
Analytical verification of doses or concentrations:
Details on analytical verification of doses or concentrations:
The N-Vinylcaprolactam concentration of the test material formulations was determined by gas chromatography incorporating a flame ionisation detector using an external standard technique .The analytical measurements of test material formulation concentrations of 25, 125 and 250 mg/mL were 26.5, 130.0 and 253.3 mg/mL, respectively. Homogenicity and stability of the test item were analytically determined.
Duration of treatment / exposure:
28 days
Frequency of treatment:
Doses / concentrations
Doses / Concentrations:
50, 250, 500 mg/kg bw/day
actual ingested
No. of animals per sex per dose:
5 animals per sex per dose in the test groups, in addition 5 animals per sex per dose were included in 2 satellite groups (0 and 500 mg/kg bw)
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale:
The dose was selected based on a range-finding study where the test substance was administered by gavage to groups of 3 male and 3 female Sprague-Dawley CFY rats at dose levels of 50, 250, 500, 750, and 1000 mg/kg bw for 14 days. A control group of 3 rats/sex was administered the vehicle. Clinical observations and body weights were monitored. All surviving animals were killed on study day 15 and subjected to full macroscopic (internal and external) examination. Tissues were not retained.
Animals treated with 50 and 250 mg/kg bw/day showed no clinically observable signs of toxicity during the 14-day study period. At 500 mg/kg bw/day moderate signs of toxicity were noted from day 3 until the end of treatment including hunched posture, pilo-erection, lethargy, red/brown staining around the snout, mouth and of the fur. Severe signs of toxicity were noted in both the 750 and 1000 mg/kg bw/day dose groups from the start of the study. Observations included those seen at 500 mg/kg bw/day with further incidents of increased salivation, ataxia, ptosis, diuresis, pallor of the extremities, emaciation, vocalisation, noisy respiration and loss of righting reflex with two females treated with 1000 mg/kg bw/ day appearing comatose on day 3. This dose group was consequently killed in extremis the same day, with the 750 mg/kg bw/day dose group being terminated on day 5 of the study as one female of this group was found dead on day 5. No effect on bodyweight was seen in the 50 and 250 mg/kg bw/day dose groups in comparison with controls. At 500 mg/kg bw/day, a reduction in bodyweight gain was noted by day 4 with one female showing an actual loss. Body weights recovered by day 8 and animals seemed to show normal gains during the remainder of the study. Animals treated with 750 mg/kg/day, the females in particular, showed losses in bodyweight during the first four days of treatment. One female rat treated with 500 mg/kg bw/day showed congested lungs. Macroscopic abnormalities noted in the 750 mg/kg bw/day dose group included pale livers, with incidents of accentuated lobular pattern, and pale kidneys. The decedent from this dose group showed congested lungs, pale liver with a small green area noted adjacent to the stomach, plus a small dark depression on the glandular region and multiple raised white foci on the non-glandular region of the stomach. Abnormalities at 1000 mg/kg bw/day included extremely pale liver and kidneys with severe -ulceration and epithelial sloughing of the glandular region of the stomach. Hydronephrosis was seen in the 50, 250 and 500 mg/kg bw/day dose groups. This finding is commonly encountered and consistent with normally expected findings in laboratory maintained rats and, as such was considered not to be treatment-related. Based on these results, dose levels of 50, 250, and 500 mg/kg bw/day were selected for the main study.

- Post-exposure recovery period in satellite groups: 14 days


Observations and examinations performed and frequency:
- Time schedule: twice daily

- Time schedule for examinations: on day before treatment and on days 7, 14, 21 and 28; and in case of satellite group, also on days 35 and 42. Body weights were also recorded at necropsy.

- Time schedule for examinations: weekly

WATER CONSUMPTION: Yes by visual inspection of the water bottles
- Time schedule for examinations: daily

- Time schedule for collection of blood: on day 28 in test groups and on day 42 in satellite groups.
- Anaesthetic used for blood collection: Yes (ether anesthesia)
- Animals fasted: No
- How many animals: all
- Parameters checked: haematocrit, haemoglobin, erythrocyte count, total leucocyte count, erythrocyte indices, plate count, differential leucocyte counts and clotting potential.

- Time schedule for collection of blood: on day 28 in test groups and on day 42 in satellite groups.
- Anaesthetic used for blood collection: Yes (ether anesthesia)
- Animals fasted: No
- How many animals: all
- Parameters checked: blood urea, total protein, sodium, potassium, chloride, calcium, inorganic phosphorus, creatinine, alkaline phosphatase, alanine aminotransferase, glucose, gamma glutamyl transpeptidase, triglycerides and total cholesterol

URINALYSIS: Yes (only in test groups)
- Time schedule for collection of urine: during week 4
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes but normal hydration
- Parameters checked: volume, specific gravity, pH, protein, glucose, ketones, bilirubin, urobilinogen, reducing substances and blood.

Sacrifice and pathology:
HISTOPATHOLOGY: Yes for the following organs:
Adrenals, Muscle (skeletal), Aorta (thoracic), Pancreas, Bone & Bone Marrow (femur), Pituitary, Brain, Rectum, Caecum, Sciatic nerve ,Colon, Skin (hind limb), Duodenum, Spleen, Eyes, Stomach, Gross lesions, Testes, Heart, Thymus, Ileum, Thyroid/parathyroid, Jejunum, Trachea, Kidneys, Urinary bladder, Liver, Oesophagus, Lungs, Ovaries, Lymph nodes (cervical and mesenteric )

All animals of test and satellite groups were killed by intravenous overdose of sodium pentobarbitone followed by exsanguination. Adrenals, brain gonads, heart, kidneys, liver, pituitary and spleen were weighed.
Relative organ weights, haematological and blood chemical data were analysed by one way analysis of variance incorporating 'F-max' test for homogeneity of variance.

Results and discussion

Results of examinations

Details on results:
CLINICAL SIGNS AND MORTALITY: No mortality was observed. Animals treated with 500 mg/kg bw/day showed signs of increased salivation, red/brown staining around the snout and mouth and pilo-erection. Slight signs of staining around the mouth and increased salivation were noted in animals treated with 250 mg/kg bw/day. Satellite high dose animals showed immediate recovery after termination of treatment. No clinically observable signs of toxicity were observed in animals treated with 50 mg/kg bw/day.

BODY WEIGHT AND WEIGHT GAIN: A slight reduction in bodyweight gain was noted during the first week only, in animals treated with 500 mg/kg bw/day.

FOOD CONSUMPTION: A slight reduction was noted during the first week only in animals treated with 500 mg/kg bw/day.

WATER CONSUMPTION: Visual inspection of water bottles throughout the study period revealed no overt intergroup differences.

HAEMATOLOGY: Clotting time was significantly increased in females from the 500 mg/kg bw/day dose group but no effects were seen in the other dose groups.

CLINICAL CHEMISTRY: A slight increase in creatinine and urea was noted for high dose males. Such a small increase in one of these parameters would not be considered toxicologically significant but an increase in both is worthy of note since they are dual indicators of renal obstruction. Similar increases were not apparent in satellite group animals after the treatment-free period.

URINALYSIS: no abnormalities were detected.

ORGAN WEIGHTS: High dose males showed a slight reduction in kidney weight compared with controls. High dose females showed significantly increased liver weight and intermediate dose females also showed an increase but less marked. Liver weights were still slightly increased in satellite high-dose females after the fourteen day treatment-free period but the severity of this was substantially reduced.

GROSS PATHOLOGY: No treatment-related macroscopic abnormalities were detected.

HISTOPATHOLOGY: NON-NEOPLASTIC: Treatment-related changes were observed in the liver of animals treated with 500 mg/kg bw/day. Changes were characterised by an increased staining intensity and tendency towards basophilia in the cytoplasm of centrilobular hepatocytes. There was no evidence of associated degenerative or inflammatory changes. No histopathological evidence of renal changes were observed.

Effect levels

open allclose all
Dose descriptor:
Effect level:
50 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: no effects
Dose descriptor:
Effect level:
250 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: liver weight

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion