5-(2-Fluoro-3-methoxyphenyl)-1-[[2-fluoro-6-(trifluoromethyl)phenyl]methyl]-6-methyl-2,4(1H,3H)-pyrimidinedione

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 February - 3 March, 2020

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

no

Test type:

fixed dose procedure

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

5-(2-fluoro-3-methoxyphenyl)-1-{[2-fluoro-6-(trifluoromethyl)phenyl]methyl}-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione

EC Number:

855-578-4

Cas Number:

1150560-59-0

Molecular formula:

C20H15F5N2O3

IUPAC Name:

5-(2-fluoro-3-methoxyphenyl)-1-{[2-fluoro-6-(trifluoromethyl)phenyl]methyl}-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione

Test material form:

solid: particulate/powder

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

not specified

Details on test animals or test system and environmental conditions:

Food was removed overnight prior to dosing and returned approximately 3 hours after dosing. Then, food was available ad libitum.

Body weights were recorded on days 1, 7, & 14

Clinical observations were made on Day 1: 0-0.5, 1, 2, 3, 4, 6, and 24 hours post dosing and on days 2-14 daily.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

Animals were weighed and administered a single dose of the test article by intragastric intubation by means of a ball tip gavage needle and a syringe.

Formulation: 0.5% Hydroxpropylmethylcellulose (HPMC)

Doses:

Dose Volume: 10 mL/kg ( all concentrations)
Sighting Study: 300 mg/kg, 2000 mg/kg
Main Study: 2000 mg/kg

No. of animals per sex per dose:

A total of 5 animals were used for each dose level. This included the animal from the sighting study administered the same dose and an additional four animals.

Control animals:

not specified

Details on study design:

Sighting Study: The purpose of the sighting study was to determine the starting dose for the main study. The test article was administered to one animal at a time in a sequential manner with at least 24 hours between the dosing of each animal. Animals were maintained for a period of at least 14 days. Dose levels were fixed at 5, 50, 300, and 2000 mg/kg. The first animal was dosed at a level expected to produce toxicity based on available in vivo or in vitro data; or at 300 mg/kg when no toxicity information was available. Depending on signs of toxicity the next animal was dosed at the next higher or next lower dose level. Dosing continued until a dose level for the Main Test was determined or death was seen at the lowest fixed dose.

Main Test: The Main Test dose was determined by the Sighting Study. A total of 5 animals were used for each dose level. This included the animal from the sighting study administered the same dose and an additional four animals. The course of the study depended on the response of the animals at the dose level for the Main Test; either the testing was stopped and the appropriate hazard classification class was assigned; or the testing continued at a higher fixed dose level; or testing continued at a lower fixed dose level. If additional dose levels were tested, the time interval between them was determined by the onset, duration, and severity of toxic signs.

After dosing, the animals were returned to their cages and supplied with feed and water ad libitum. Clinical observations were made at least once during the first 30 minutes with
special attention given during the first 6 hours and then at least daily for a period of 14 days. The frequency was determined by the response of the test animals to the treatment. However, the duration of observation was not fixed rigidly. It was determined by the toxic reactions, rate of onset and length of recovery period, and could thus be extended when considered necessary. The time at which signs of toxicity appeared and disappeared and the time of death were important, especially if there was a tendency for deaths to be delayed. All observations were recorded and individual records were maintained for each animal. Cageside observations included changes in skin and fur, eyes and mucous membranes, and also respiratory, circulatory, autonomic, and central nervous system, and somatomotor activity and behavior pattern. Particular attention was directed to observations of tremors, convulsions, salivation, diarrhea, lethargy, sleep and coma. The time of death was recorded
as precisely as possible. Moribund animals that were killed for humane reasons were considered in the same way as animals that died on test.

Animals were weighed weekly and at the end of the observation period and then are sacrificed by exsanguination under deep anesthesia with intraperitoneal ketamine (100 mg/ kg) and xylazine (10 mg/ kg). Changes in weights were calculated and recorded when survival exceeded one day. Any animal found dead was necropsied as soon as possible, but in no case later than 12 hours after discovery. A gross necropsy was performed on all animals whether found dead, sacrificed in extremis, or sacrificed at the end of the study and all gross pathological changes were recorded. An evaluation of acute toxicity data included the relationship, if any, between the animals exposed to the test article and the incidence and severity of all abnormalities, including behavioral and clinical abnormalities, gross lesions, body weight changes, effects on
mortality, and any other toxic effects.

Results and discussion

Preliminary study:

Animal 2002 was dosed at 300 mg/kg as there was no information available on toxicity. Starting approximately 1 hour after dosing mildly decreased activity was
observed, which lasted until the 2 h time point. To gain more information on the toxicologic profile of the test material, animal 2004 was dosed the next day at the next higher dose of 2000 mg/kg. Starting approximately 1 hour after dosing clinical signs including rough hair, piloerection, walking on toes and decreased activity were observed. All clinical signs in animal 2004 were resolved 6 hours after dosing and the animal appeared normal. Based on these observations 2000 mg/kg was chosen for the main study with the test material.

Effect levels

Key result

Sex:

not specified

Dose descriptor:

approximate LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

Using OECD 420 Fixed Dose Procedure (main test), five animals survived the dose of 2000 mg/kg

Clinical signs:

other: Four additional animals (2006, 2008, 2010 and 2012) were dosed with the test material at 2000 mg/kg. All four animals showed clinical signs of decreased activity and a rough coat starting 1 hour p.a (2008, 2010 and 2012) or 3 hours p.a. (2006). No more cl

Gross pathology:

There were no findings during gross necropsy in any of the main study animals at the end of study; all tissues appeared normal.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test material was evaluated for potential acute toxicity following oral administration. Using OECD 420 Fixed Dose Procedure (main test), five animals survived the dose of 2000 mg/kg. Therefore, the test item was defined to have an estimated LD50>2000 mg/kg and therefore classified as a Hazard Category of 5 according to Globally Harmonized System (GHS). However, because category 5 is not implemented in the EU, GHS criteria was considered to be not met.