2-(3-Chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylic acid ethyl ester

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 2006 - October 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2001

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Version / remarks:

2002

GLP compliance:

yes

Test type:

up-and-down procedure

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

ethyl 2-(3-chloropyridin-2-yl)-5-oxopyrazolidine-3-carboxylate

EC Number:

610-490-3

Cas Number:

500011-88-1

Molecular formula:

C11H12ClN3O3

IUPAC Name:

ethyl 2-(3-chloropyridin-2-yl)-5-oxopyrazolidine-3-carboxylate

Test material form:

solid

Test animals

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, NC
- Females (if applicable) nulliparous and non-pregnant: not reported
- Age at study initiation: Approximately 10 or 11 weeks old
- Weight at study initiation: 196.7–244.1 g
- Fasting period before study: 16-18.5 hours prior to dosing
- Housing: Animals were housed singly in stainless steel, wire-mesh
cages suspended above cage boards.
- Diet: PMI Nutrition International, LLC Certified Rodent LabDiet (#5002), ad libitum
- Water: Tap water, ad libitum
- Acclimation period: At least 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 − 26°C
- Humidity (%): 30–70%
- Air changes (per hr): Not recorded
- Photoperiod (hrs dark / hrs light): Alternating 12-hour light and dark cycles

IN-LIFE DATES: From: 10 May 2006 to 16 August 2006

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 0.5% aqueous methylcellulose

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 175; 550; 1750; 5000 mg/kg
- Amount of vehicle (if gavage): 10 mL/kg

Doses:

175; 550; 1750; 5000 mg/kg bw

No. of animals per sex per dose:

175 mg/kg: 1 female rat
550 mg/kg: 1 female rat
1750 mg/kg: 2 female rats
5000 mg/kg: 5 female rats

Control animals:

no

Details on study design:

A single oral dose of the test item, suspended in 0.5% aqueous methylcellulose, was administered by intragastric intubation to one fasted female rat each at a dose of 175 or 550 mg/kg; to two fasted female rats at a dose of 1750 mg/kg; and to five fasted female rats at a dose of 5000 mg/kg. The animals were dosed one at a time at a minimum of 48-hour intervals.

The animals were observed for clinical signs just before dosing, once during the first 30 minutes after dosing and 2 more times within 4 hours after dosing, and once each day thereafter.
The animals were weighed on test Days -1, 0, 7, and 14. One rat was weighed on Day 1. Another rat was also weighed on Days 12, 13, and 15-21. The observation period for this rat was extended to 21 days to ensure survival. This rat was necropsied on test day 21. On test day 14, the remaining surviving rats were
euthanized and necropsied to detect grossly observable evidence of organ or tissue damage or dysfunction.

Statistics:

A software package (A0T425StatPgm) was used to determine the dose progression and to calculate the LD50.

Results and discussion

Effect levels

Sex:

female

Dose descriptor:

LD50

Effect level:

5 000 mg/kg bw

Based on:

test mat.

Mortality:

One rat dosed at 5000 mg/kg was found dead 2 days after dosing. The death of a rat dosed at 1750 mg/kg was attributed to gavage trauma. This rat was not used in the LD50 determination. The dose progression and mortality are detailed in Table 1 and Table 2.

Clinical signs:

other: Four rats dosed at 5000 mg/kg exhibited various staining, wet fur, high carriage, abnormal gait or posture, absent feces, and/or not eating during the study. No clinical signs of toxicity were observed in the remaining rats.

Gross pathology:

Gross findings were present in rats administered 1750 and 5000 mg/kg. These included esophagus rupture in rat 3554 (sacrificed in extremis, 1750 mg/kg), which was determined to be gavage error; and lungs discoloration in rat 3214 (sacrificed by design, 5000 mg/kg).
No other gross findings were observed.

Any other information on results incl. tables

Table 1: Acute oral toxicity of test item: Dose progression and mortality

 

Test sequence	Animal ID	Dose (mg/kg bw)	Short-term result	Long-term result
1	3252	175	O	O
2	3257	550	O	O
3	3616	1750	O	O
4	3620	5000	O	O
5	3735	5000	X	X
6	3735	1750	O	O
7	3970	5000	O	O
8	3214	5000	O	O
9	6242	5000	O	O

(X = Died, O = Survived)

Dose Recommendation: The main test is complete.
Stopping criteria met: 3 at limit dose.

 

Table 2: Acute oral toxicity of test item: Summary of long term results

 

Dose	O	X	Total
175	1	0	1
550	1	0	1
1750	2	0	2
5000	4	1	5
All doses	8	1	9

(X = Died, O = Survived)

Statistical Estimate based on long term outcomes: Estimated LD50 = 5000 mg/kg (the one dose with partial response). 95% Profile likelihood confidence interval is 4140 to greater than 20,000 mg/kg.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of this study, the oral LD50 for the test item was 5000 mg/kg bw for female rats.

Executive summary:

The acute oral toxicity of the test item was investigated according to OECD Guideline 425, Acute Oral Toxicity: Up-and-Down Procedure.

A single oral dose of test item, suspended in 0.5% aqueous methylcellulose, was administered by intragastric intubation to one fasted female rat each at a dose of 175 or 550 mg/kg, to two fasted female rats at a dose of 1750 mg/kg, and to five fasted female rats at a dose of 5000 mg/kg. The animals were dosed one at a time at a minimum of 46.5-hour intervals. Animals were observed for clinical signs of toxicity, body weight effects, and mortality for up to 21 days after dosing. All animals were examined to detect grossly observable evidence of organ or tissue damage or dysfunction. A software package (A0T425StatPgm) was used to determine the dose progression and to calculate the LD50.

Oral LD50 (Female rats) = 5000 mg/kg bw

One rat dosed at 5000 mg/kg was found dead 2 days after dosing. No other deaths occurred. Four rats dosed at 5000 mg/kg exhibited various staining, wet fur, high carriage, abnormal gait or posture, absent feces, and/or not eating during the study. No clinical signs of toxicity were observed in the remaining rats. Body weight loss of 18% occurred by 15 days after dosing in one of the rats dosed at 5000 mg/kg. This rat also exhibited weight loss of 4% between days 18 and 19. No other body weight losses occurred. Gross findings were present in rats administered 1750 and 5000 mg/kg. These included esophagus rupture in rat 3554 (sacrificed in extremis, 1750 mg/kg), which was determined to be gavage error; and lungs discoloration in rat 3214 (sacrificed by design, 5000 mg/kg). No other gross findings were observed.

Based on the results of the present study, classification by the oral route is not required.