1H-Pyrazole-5-carboxylic acid, 3-bromo-1-(3-chloro-2-pyridinyl)-

Endpoint summary

Description of key information

In an acute oral toxicity study according to OECD 425 in female Wistar rats, the toxicological profile of 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid was assessed. The determined median lethal dose LD50 was greater than 5000 mg/kg body weight.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 January 2020 to 08 June 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 425 (Acute Oral Toxicity: Up-and-Down Procedure)

Version / remarks:

October 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Version / remarks:

December 2002

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

up-and-down procedure

Limit test:

yes

Specific details on test material used for the study:

Storage Condition (at JRF):
Storage Temperature: Room temperature (15 to 30 °C).
Storage Condition: Cool and dry conditions.
Storage Container: In original container as supplied by the Sponsor.
Storage Location: Test Item Control Office, JRF.

Species:

rat

Strain:

other: RccHan: WIST

Sex:

female

Details on test animals or test system and environmental conditions:

Species: Rat (Rattus norvegicus).
Strain: RccHan: WIST.
Age/Weight at Dosing: 9 to 12 weeks, Weight (g) Minimum: 193.4, Maximum: 235.6.
Source: Animal Breeding Facility, Jai Research Foundation.
Total Number of Animals Used: Six females (nulliparous and non-pregnant).

Acclimatisation: 7 to 18 days.

Animal Identification: Each rat was uniquely numbered on the tail using a tattoo machine on day 1 of acclimatisation. Appropriate labels were attached to the cages indicating the study number, test item code, group number, sex, dose, type of study, cage number and animal number.

Caging: Polypropylene rat cages covered with stainless-steel grid top were used. Autoclaved clean rice husk was used as the bedding material. Wooden blocks were provided as enrichment material.

Water Bottle: Each cage was supplied with a polypropylene water bottle with a stainless-steel nozzle.
Housing: Maximum of three rats per cage, Room No. BMR 28.

Room Sanitation, daily:
1. Rack was cleaned with cloth.
2. Floor of experimental procedure room was swept.
3. All work tops and the floor were mopped with a disinfectant solution (Dettol 2.5%).

Feed and Water
The rats were provided with feed and water, ad libitum. The quality of feed and water is regularly monitored at Jai Research Foundation. There were no known contaminants in the feed and water at levels that would have interfered with the experimental results obtained.
Feed: Teklad certified Global High Fiber Rat/Mice Feed manufactured by Envigo, USA.
Water: UV sterilised water filtered through Reverse Osmosis water filtration system.

Environmental Conditions
Animal Room: BMR 28, Department of Toxicology.
Temperature: 20 to 23°C.
Relative Humidity: 56 to 66%.
Air Changes: Minimum 15 air changes/hour.
Photoperiod: The photoperiod was 12 hours artificial light and 12 hours darkness, light hours being 06:00 h–18:00 h (photoperiod was maintained through automatic timer).

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

VEHICLE/Control ITEM
- The test item was found to be insoluble and did not form a homogenous suspension in water as well as 0.5% aqueous carboxymethylcellulose solution. The test item was found to be forming a homogenous suspension in corn oil the same was used as vehicle in the study.

- Required amount of test item (175, 550, 1750 or 5000 mg) was mixed in corn oil and then adjusted according to the body weight to permit a constant dose volume (10 mL/kg body weight).
- Gavage solutions were prepared freshly prior to dosing on all the occasions.

- Concentration in vehicle: Individual dose volume was adjusted according to body weight and dose level (10 mL/kg body weight):
Dose: 175 mg/kg = Dose Volume administered: 1.93 mL.
Dose: 550 mg/kg = Dose Volume administered: 2.21 mL.
Dose: 1750 mg/kg = Dose Volume administered: 2.10 mL.
Dose: 5000 mg/kg = Dose Volume administered: 2.25–2.36 mL.
- Amount of vehicle: a constant volume of 10 mL/kg body weight.

ORAL GAVAGE
- All rats were dosed by oral gavage (day 0) using a metal cannula attached to a BD 1 mL disposable syringe, which was graduated up to 1 mL.
Rats were fasted overnight, prior to dosing, until three hours post-dosing.

Doses:

Dose: 175 mg/kg = Dose Volume administered: 1.93 mL.
Dose: 550 mg/kg = Dose Volume administered: 2.21 mL.
Dose 1750 mg/kg = Dose Volume administered: 2.10 mL.
Dose: 5000 mg/kg = Dose Volume administered: 2.25–2.36 mL.

No. of animals per sex per dose:

one animal/female/Dose: 175 mg/kg
one animal/female/Dose: 550 mg/kg
one animal/female/Dose: 1750 mg/kg
three animals/female/Dose: 5000 mg/kg

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: At 0.5, 1, 2, 3, 4 and 5 h post-administration on the day of dosing.
- Necropsy of survivors performed: yes
- Clinical signs including body weight: The clinical signs were recorded at least once a day. Individual body weight was recorded prior to dosing on day 0, and on days 7 and 14 and at death.

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

95% CL:

> 175 - <= 5 000

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No mortality was observed in rats treated with 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid.

Clinical signs:

other: No clinical signs were observed in rats treated with 175 mg/kg body weight (rat N° 1), 550 mg/kg body weight (rat N° 2), 1750 mg/kg body weight (rat N° 3) or 5000 mg/kg body weight (rat N° 4, 5, and 6).

Gross pathology:

External Examination
There were no external abnormalities in any rats which were sacrificed at the scheduled termination.

Internal Examination
There were no internal abnormalities in any rats which were sacrificed at scheduled termination.
In the absence of any pathological lesion in terminally sacrificed animals, it is concluded that the test item did not produce any treatment related effect at the dose levels used in the present study.

Dose, Mortality/Rats treated:

Dose (mg/kg body weight)	Female rats (mortality/total)
175	0/1
550	0/1
1750	0/1
5000	0/3

Test Sequence and Mortalities:

Rat N°	Dose (mg/kg body weight)	Mortality after Dosing
		½ - 5 h	24 h	48 h	72 h	4 – 7 Day	8 – 14 Day
1	175	O	O	O	O	O	O
2	550	O	O	O	O	O	O
3	1750	O	O	O	O	O	O
4	5000	O	O	O	O	O	O
5	5000	O	O	O	O	O	O
6	5000	O	O	O	O	O	O

Note: O = Survived

Individual Clinical Observations:

Rat N°	Dose (mg/kg body weight)	Clinical Signs Observed after Dosing
		At Hour (Day 0)						On Day
		0.5	1	2	3	4	5	1	2	3	4	5	6	7	8	9	10	11	12	13	14
1	175	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
2	550	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
3	1750	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
4	5000	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
5	5000	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
6	5000	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1

Note: Day 0 = Day of dosing

Clinical Sign: 1 = Normal

Individual Necropsy Findings:

Rat N°	Dose (mg/kg body weight)	Mode of Death	External	Internal
1	175	Terminal sacrifice	No abnormality detected	No abnormality detected
2	550	Terminal sacrifice	No abnormality detected	No abnormality detected
3	1750	Terminal sacrifice	No abnormality detected	No abnormality detected
4	5000	Terminal sacrifice	No abnormality detected	No abnormality detected
5	5000	Terminal sacrifice	No abnormality detected	No abnormality detected
6	5000	Terminal sacrifice	No abnormality detected	No abnormality detected

Interpretation of Results

The LD50 was calculated using the Dixon’s maximum likelihood method using software (AOT 425 StatPgm) and was found to be greater than 5000 mg/kg body weight.

Interpretation of results:

GHS criteria not met

Conclusions:

Based on results of this study, the acute oral median lethal dose for 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid in Wistar rats was found to be greater than 5000 mg/kg body weight. In accordance with the provisions of regulation 1272/2008, Annex I, 3.1, it is proposed classification is not required.

Executive summary:

In an acute oral toxicity study in female Wistar rats (9 to 12 weeks old), the toxicological profile of 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid was assessed and the median lethal dose determined. A single oral dose of 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid was administered orally to fasted rats (formulated using corn oil as a vehicle and at a constant dose volume of 10 mL/kg) through gavage. Initially rat N° 1 was tested with a starting dose level of 175 mg 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid/kg body weight. The tested rat survived at this dose level, subsequently five additional female Wistar rats received the dose of 550 mg 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid/kg body weight (rat N° 2), 1750 mg 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid/kg body weight (rat N° 3) and 5000 mg/kg body weight (rat N° 4, 5, and 6), according to the Up and Down Procedure. All rats were observed for 14 days following dose administration.

 

There was no treatment-related mortality, no changes in body weight, or necropsy finding recorded.

 

No clinical signs were observed in rats treated with 175 mg/kg body weight (rat N° 1), 550 mg/kg body weight (rat N° 2), 1750 mg/kg body weight (rat N° 3) or 5000 mg/kg body weight (rat N° 4, 5, and 6).

 

The number of animals which died or showed evident toxicity is shown below:

Dose (mg/kg bw)	Mortality (# dead/total)	Time range of deaths (h)	Evident toxicity  (#/total)
175	0/1	-	0/1
550	0/1	-	0/1
1750	0/1	-	0/1
5000	0/3	-	0/3

In accordance with the provisions of regulation 1272/2008, Annex I, 3.1, it is proposed classification is not required.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

According to OECD test 425 provided with an median lethal dose of LD50 = > 5000 mg/kg bw by oral administration, it is proposed classification is not required.