ethynyl cyclopropane

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method B.1 bis (Acute Oral Toxicity - Fixed Dose Procedure)

Principles of method if other than guideline:

The method followed was based on that described in the EEC Methods for the determination of toxicity, Annex to Directive 92/69/EEC (OJ No. L383A, 29.12.92), Part B. Method B .1 bis . Acute toxicity (oral) - fixed dose method.

GLP compliance:

yes

Test type:

fixed dose procedure

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

425-430-1

EC Name:

-

Cas Number:

6746-94-7

Molecular formula:

C5 H6

IUPAC Name:

ethynylcyclopropane

Details on test material:

- Name of test material (as cited in study report): EthynyI cyclopropane (SD 957)
- Physical state: Colourless liquid
- Analytical purity: 97-100 %
- Lot/batch No.: 3590-129-D4
- Expiration date of the lot/batch: January 1999
- Storage condition of test material: -20°C, under nitrogen and in the dark
- Intended use: Pharmaceutical intermediate

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan UK Ltd, Bicester, Oxon, England
- Age at study initiation: four to six weeks
- Weight at study initiation: 125 to 174 g
- Fasting period before study: no data
- Diet: standard laboratory rodent diet (Special Diet Services RM I (E) SQC expanded pellet) ad libitum
- Water: drinking water ad libitum
- Acclimation period: for a minimum period of five days prior to the start of the study


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 55 ± 15
- Air changes (per hr): 12 to 15
- Photoperiod (hrs dark / hrs light): 12/12

The batch(s) of diet used for the study was analysed for certain nutrients, possible contaminants and microorganisms.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

MAXIMUM DOSE VOLUME APPLIED: 2.556 ml/kg


DOSAGE PREPARATION:
SD 957 was administered, as supplied by the Sponsor, at various dose volumes to achieve the required dose concentration. A sub-sample of SD 957 was transported just prior to dosing in a closed container at ambient temperature from the Department of formulation to the animal holding area. In the main phase of the study, the test substance was retained in a fume cupboard housed in a walk-in ventilated cabinet which was separated from the cabinets in the main room 111 which the animals were housed. The absorption of the test substance was not determined. Characterisation of the homogeneity, stability and purity of the test substance was not undertaken in this study and remains the responsibility of the sponsor.

Doses:

500, 2000 mg/kg bw

No. of animals per sex per dose:

5 males, 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: daily
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

TREATMENT PROCEDURE
Preliminary study
A female rat was treated at 500 mg/kg, after review of results a further female was treated at 2000 mg/kg bodyweight in order to select a dosing regime for the main study.

Main study
A group of ten rats (five males and five females) was treated at 2000 mg/kg bodyweight . A further ten rats were similarly treated at 500 mg/kg after review of results in order to define the discriminating dose. The treatment regime and constitution of the groups are as follows:

Dates Dose Dose volume No. of rats
dosed (mg/kg) (ml/kg) Male Female

25.02.97 500 0.639 - 1
28.02.97 2000 2.556 - 1
03.03.97 2000 2.556 5 5
10.03.97 500 0.639 5 5
12.03.97 500 0.639 1* 1*

*: Replacement animals

OBSERVATIONS
Mortality
Cages of rats were checked at least twice daily for any mortalities.

Clinical signs
Animals in the main study were observed soon after dosing and at hourly intervals for the remainder of Day 1. On subsequent days animals were observed once in the morning and again at the end of the experimental day (with the exception of Day 15 - morning only). The nature and severity of the clinical signs and time were recorded at each observation.

The animals on the preliminary study and those surviving treatment on the main study were observed for 7 or 14 days respectively after dosing.

Bodyweight
The bodyweight of each rat in the main study was recorded on Days 1 (prior to dosing), 2, 3, 4, 8 and 15, or at death. Individual weekly bodyweight changes and group mean bodyweights were calculated .

TERMINAL STUDIES
Termination
All surviving animals were killed on either Day 8 (preliminary study) or Day 15 (main study).

Macroscopic pathology
All animals were subjected to a macroscopic examination which consisted of opening the cranial, abdominal and thoracic cavities. The macroscopic appearance of all tissues was recorded.

Results and discussion

Preliminary study:

There were no deaths following a single oral administration to one female rat at 500 mg/kg or to a further female at 2000 mg/kg. A minimal systemic response was evident in the rat treated at 500 mg/kg, with a more notable response in the rat treated at 2000 mg/kg. The response notable at 2000 mg/kg although pronounced did not appear to be life threatening and on this basis it was considered -that 2000 mg/kg bodyweight was a stumble dosage for animals in the main study.

Effect levels

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Mortality:

One male and two females treated at 2000 mg/kg died during the study. Deaths occurred between three and a half hours and four days post dose. Macroscopic examination of these animals (was undertaken in all instances within thirty minutes of finding the animals dead) revealed changes considered to be congestive in nature (characterized by darkened tissue, prominent blood vessels and/or fluid contents and gaseous distension along the gastro - intestinal tract) involving all or the majority of organs and tissues.

Clinical signs:

other: Clinical signs were first evident within minutes of dosing. Piloerection was seen in all rats at both 500 and 2000 mg/kg, in rats at 2000 mg/kg only, signs comprised piloerection, respiratory distress, hunched posture, waddling/unsteady gait and walking o

Gross pathology:

Macroscopic examination of rats treated at 2000 mg/kg killed at study termination revealed slight congestion in the lungs. No abnormalities were observed at the study termination necropsy of animals treated at 500 mg/kg.

Any other information on results incl. tables

MAIN STUDY

A group of ten rats (five males and five females) was dosed at 2000 mg/kg bodyweight (EU limit dose). As a result of mortalities at the limit dose (and as the preliminary study indicated the response at 500 mg/kg to be suitable) a further group of ten rats was dosed at 500 mg/kg bodyweight. As a result of a deterioration in health of two out of the ten rats treated at 500 mg/kg and subsequent death of one of these animals, two additional animals were treated. The decision to replace the two affected animals (at 500 mg/kg) was taken on the basis that the initial preliminary study animal treated at 500 mg/kg showed only a minimal response following treatment and the remaining four males and four females in the main study at 500 mg/kg also only showed a similar minimal response. It was therefore considered the deterioration in health of both animals and subsequent death of one of these animals was associated in some manner to inadvertent inhalation of vapour from the test material, particularly as the initial response in both animals was respiratory distress (with subsequent deterioration in health considered to be associated with the labored breathing and stress from the treatment procedure). In addition macroscopic findings in the decedent male revealed swollen congested lungs . Based on these findings, it is reasonable to assume the response observed in the two affected animals at 500 mg/kg was not as a direct result of the oral ingestion of SD 957 and on this basis treatment of additional animals to verify the above considerations was considered justified.