4-methylpyrazole

Repeated dose toxicity: other routes

Administrative data

Endpoint:

short-term repeated dose toxicity: other route

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Animal experimental study, published in peer reviewed literature.

Data source

Reference

Reference Type:

publication

Title:

Normal electroretinogram and no toxicity signs after chronic and acute administration of the alcohol dehydrogenase inhibitor 4-methylpyrazole to the cynomolgus monkey (Macaca fascicularis)-a possible new treatment of methanol poisoning.

Author:

Blomstrand R.

Year:

1984

Bibliographic source:

Drug Alcohol Depend. 1984 Jan;13(1):9-20.

Materials and methods

Principles of method if other than guideline:

Four male Macaca fascicularis monkeys per dose were injected intramuscular with the test substance once a day, 5 times/week for 6 weeks. Ophthalmoscopic examinations and ERG recordings were performed, haematology and clinical chemistry were examined, and clinical signs recorded. After an observation period of an additional 72 hours animals were necropsied.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

4-methylpyrazole

EC Number:

231-445-0

EC Name:

4-methylpyrazole

Cas Number:

7554-65-6

Molecular formula:

C4H6N2

IUPAC Name:

4-methyl-1H-pyrazole

Details on test material:

Name of test material (as cited in study article): 4-methylpyrazole (4-MP)

Test animals

Species:

monkey

Strain:

Macaca fascicularis

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 2.1 - 3 kg
- Diet: ad libitum
- Water: ad libitum

Administration / exposure

Route of administration:

intramuscular

Vehicle:

physiological saline

Details on exposure:

Injection in 2-10% solutions

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

6 weeks

Frequency of treatment:

Once a day, 5 days/week

Doses / concentrations

Remarks:

Doses / Concentrations:
- Group 2: 20 mg/kg
- Group 3: 100 mg/kg for 5 weeks, and 200 mg/kg in the last week

No. of animals per sex per dose:

4

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: 72 h after the last injections

Examinations

Observations and examinations performed and frequency:

- DETAILED CLINICAL OBSERVATIONS: Animals were carefully observed for clinical signs of intoxication during the course of the experiment.
- OPHTHALMOSCOPIC EXAMINATION: It was performed after 3 weeks and repeated 72 hours after the last injection at the end of the study.
- HAEMATOLOGY: Before the start of the experiment and at the end of the experiment blood samples were collected for determination of hemoglobin, number of erythrocytes, leucocytes and platelets, and blood cell microscopy.
- CLINICAL CHEMISTRY: Before the start of the experiment and at the end of the experiment blood samples were collected for determination of aminotransferases ASAT and ALAT, alkaline phosphatase, bilirubin, N-urea and glucose.
- CONCENTRATION IN BLOOD: From the second week and once a week afterwards, blood samples were taken for analysis of the serum levels of 4-MP in group 3. In group 2 the serum levels were checked only after 6 weeks.
- ERG: During the ERG recording, the heads and bodies of the naimals were held by means of plastic support. Pupils were dilated (by Mydriacyl® and 10% Neosynephrine®), photographs were taken from the left eye and ERG was recorded on the right eye. 45 min before the ERG animals were dark-adapted. The ERG was elicited with a strobe lamp connected to a pulse generator (Grass model PS 22). The signal was displayed on storage oscilloscope and photographed.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes. Tissue samples were taken from the brain, spinal cord, sciatic nerve, eyes, heart, liver, kidney and the spleen.

Results and discussion

Results of examinations

Details on results:

CLINICAL SIGNS AND MORTALITY
In the third week, one monkey from group 3 died during anaesthesia. No test substance related clinical toxic reactions were observed in all exposed animals. All animals were in good shape, well nourished, alert, strong and showed a normal behavioural pattern.

OPHTHALMOSCOPIC EXAMINATION
No changes during the course of the experiments were observed.

HAEMATOLOGY and CLINICAL CHEMISTRY
No effects were observed in comparison with animals in the control group in all parameters.

GROSS PATHOLOGY and HISTOPATHOLOGY
No gross and microscopic morphological effects were observed.

CONCENTRATION
Animals in group 3 had very high and rather constant serum levels for the first 5 weeks, the range being between 204 and 1154 µM/L, then the values increased considerably (range 1742 – 2353 µM/L) the last week when the dose levels were doubled. Serum levels in group 2 were only taken at the end of the study. In three animals is was roughly similar (37 – 45 µM/L), but in one animal is much higher (425 µM/L).

Target system / organ toxicity

Critical effects observed:

not specified