N-(2-oxo-1,2-dihydropyrimidin-4-yl)benzamide

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental start date: 04 December 2012. Experimental end date: 03 January 2013.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 420 (Acute Oral Toxicity - Fixed Dose Method)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

fixed dose procedure

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

N4-Benzoylcytosine

EC Number:

628-907-2

Cas Number:

26661-13-2

Molecular formula:

C11H9N3O2

IUPAC Name:

N4-Benzoylcytosine

Specific details on test material used for the study:

Sponsor's identification: N-Benzoyl Cytosine
Description: off white powder
Batch number: NBC-5-11001
Purity: not supplied
Date received: 09 July 2012
Expiry date: not supplied
Storage conditions: room temperature in the dark over silica gel

Test animals

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

Female Wistar (RccHan :WIST) strain rats were supplied by Harlan Laboratories UK Ltd., Oxon, UK. On receipt the animals were randomly allocated to cages. The females were nulliparous and non-pregnant. After an acclimatisation period of at least five days the animals were selected at random and given a number unique within the study by indelible ink-marking on the tail and a number written on a cage card. At the start of the study the animals were eight to twelve weeks of age. The bodyweight variation did not exceed ±20% of the bodyweight of the initially dosed animal.
The animals were housed in groups of up to four in suspended solid-floor polypropylene cages furnished with woodflakes. With the exception of an overnight fast immediately before dosing and for approximately three to four hours after dosing, free access to mains drinking water and food (2014C Teklad Global Rodent diet supplied by Harlan Laboratories UK Ltd., Oxon, UK) was allowed throughout the study. The diet, drinking water and bedding were routinely analysed and were considered not to contain any contaminants that would reasonably be expected to affect the purpose or integrity of the study.
The temperature and relative humidity were set to achieve limits of 19 to 25°C and 30 to 70% respectively. Any occasional deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was at least fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness. The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

For the purpose of the study the test item was freshly prepared, as required, as a suspension in arachis oil BP. Arachis oil BP was used because the test item did not dissolve/suspend suitably in distilled water.
The test item was formulated within two hours of being applied to the test system. It is assumed that the formulation was stable for this duration. No analysis was conducted to determine the homogeneity, concentration or stability of
the test item formulation. This is an exception with regard to GLP and has been reflected in the GLP compliance statement.

Doses:

300 mg/kg
2000 mg/kg

No. of animals per sex per dose:

1 female at 300 mg/kg
4 females at 2000 mg/kg

Control animals:

no

Details on study design:

Using available information on the toxicity of the test item, 300 mg/kg was chosen as the starting dose.
In the absence of toxicity at a dose level of 300 mg/kg, an additional animal were treated at 2000 mg/kg.
In the absence of toxicity at a dose level of 2000 mg/kg, an additional group of animals were treated at 2000 mg/kg.
A total of five animals were therefore treated at a dose level of 2000 mg/kg in the study.
All animals were dosed once only by gavage, using a metal cannula attached to a graduated syringe. The volume administered to each animal was calculated according to the fasted bodyweight at the time of dosing. Treatment of animals was sequential. Sufficient time was allowed between each dose level to confirm the survival of the previously dosed animals.
Clinical observations were made 14, 1, 2, and 4 hours after dosing and then daily for fourteen days. Morbidity and mortality checks were made twice daily.
Individual bodyweights were recorded on Day 0 (the day of dosing) and on Days 7 and 14.
At the end of the observation period the animals were killed by cervical dislocation. All animals were subjected to gross necropsy. This consisted of an external examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded. No tissues were retained.

Results and discussion

Effect levels

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

There was no mortality at 300 mg/kg or 2000 mg/kg

Clinical signs:

No signs of systemic toxicity were noted during the observation period, at either 300 mg/kg or 2000 mg/kg.

Body weight:

The animal showed expected gains in bodyweight over the observation period at 300 mg/kg. Animals showed expected gains in bodyweight over the observation period, except for one animal treated at a dose level of 2000 mg/kg which showed expected gain in body weight during the first week but bodyweight loss during the second week.

Gross pathology:

No abnormalities were noted at necropsy at 300 mg/kg or 2000 mg/kg.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The acute oral median lethal dose (LD50) of the test item in the female Wistar strain rat was estimated to be greater than 2000 mg/kg bodyweight (Globally Harmonised Classification System - Unclassified).

Executive summary:

Introduction

The study was performed to assess the acute oral toxicity of the test item in the Wistar strain rat. The method was designed to be compatible with the following:

OECD Guidelines for Testing of Chemicals No 420 “Acute Oral Toxicity - Fixed Dose Method” (2001)

Method B1 bis Acute Toxicity (Oral) of Commission Regulation (EC) No. 440/2008

Method

Following a sighting test at dose levels of 300 mg/kg and 2000 mg/kg, a further group of four fasted females was given a single oral dose of test item, as a suspension in arachis oil BP, at a dose level of 2000 mg/kg bodyweight. Clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

Mortality

There were no deaths.

Clinical Observations

There were no signs of systemic toxicity.

Bodyweight.

Animals showed expected gains in bodyweight over the observation period, except for one animal treated at a dose level of 2000 mg/kg which showed expected gain in body weight during the first week but bodyweight loss during the second week.

Necropsy

No abnormalities were noted at necropsy.

Conclusion

The acute oral median lethal dose (LD₅₀) of the test item in the female Wistar strain rat was estimated to be greater than 2000 mg/kg bodyweight (Globally Harmonised Classification System - Unclassified).