[1,2,4]Triazolo[1,5-a]pyrimidin-2-amine, 5,7-dimethoxy-

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 21 - February 18, 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Deviations:

yes

Principles of method if other than guideline:

DEVIATION FROM THE FINAL PROTOCOL
The protocol requires that food be returned immediately following the test substance administration. Due to a technician error, the re-feeding time of animal #656 was inadvertently not recorded. However, it is Product Safety Laboratories standard operating procedure to perform a viability check in the morning and afternoon hours. Although this animal died on Day 2, confirmation that the animal had food available was recorded in the room record. This deviation did not adversely impact the outcome of this study and is not considered to justify a reduction in the Klimisch reliability rating of the study.

GLP compliance:

yes

Test type:

up-and-down procedure

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

5,7-dimethoxy-[1,2,4]triazolo[1,5-a]pyrimidin-2-amine

EC Number:

603-562-0

Cas Number:

13223-43-3

Molecular formula:

C7H9N5O2

IUPAC Name:

5,7-dimethoxy-[1,2,4]triazolo[1,5-a]pyrimidin-2-amine

Details on test material:

- Name of test material (as cited in study report): ADTP
- Physical state: off-white solid
- Analytical purity: 99.8%
- Lot/batch No.: 041206-5D
- Expiration date of the lot/batch: n/a
- Stability under test conditions: Test substance was expected to be stable for the duration of testing.
- Storage condition of test material: room temperature
- pH: 7-8 (by wetted pH paper)

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Received from Charles River Laboratories, Raleigh, NC on January 11, 2005.
- Age at study initiation: Young adult (9-12 weeks)
- Weight at study initiation: 136-158 grams at experimental start
- Fasting period before study: Prior to each dosing, experimentally naive rats were fasted overnight by removing the feed from their cages. During the fasting period, the rats were examined for health and weighed (initial).
- Housing: The animals were singly housed in suspended stainless steel caging with mesh floors which conform to the size recommendations in the most recent Guide for the Care and Use of Laboratory Animals DHEW (NIH). Litter paper was placed beneath the cage and was changed at least three times per week.
- Diet (e.g. ad libitum): Purina Certified Rodent Diet (PMI #5002)
- Water (e.g. ad libitum): Filtered tap water was supplied ad-libitum by an automatic water dispensing system.
- Acclimation period: 10-27 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-24°C
- Humidity (%): 31-69% RH
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle

Administration / exposure

Route of administration:

oral: gavage

Details on oral exposure:

Individual doses were calculated based on the initial body weights, taking into account the specific gravity (determined by PSL) and concentration of the test mixture.
The test substance was administered as a 25% w/w mixture in distilled water using a stainless steel ball-tipped gavage needle attached to an appropriate syringe. Following administration, each animal was returned to its designated cage. Feed was replaced immediately after dosing.

Doses:

Individual animals were dosed as follows:

Main Test
Dosing Sequence Animal No. Dose Level (mg/kg) Short-Term Outcome Long-Term Outcome
1 419 175 S S
2 468 550 S S
3 566 1,750 D D
4 630 550 S S
5 656 1,750 D D
6 720 550 S S
7 733 1,750 D D

S = survival, D = death

The test substance was administered in sequence to the animals as described above. The decision to proceed with the next animal was based on the survival of the previous animal in the short-term period following dosing. Dose progressions and stopping criteria were determined using a statistical program.

No. of animals per sex per dose:

A total of 7 Female, nulliparous and non-pregnant rats were used in this study. (175 mg/kg = 1 animal; 550 & 1750 mg/kg = 3 animals)

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The animals were observed for mortality, signs of gross toxicity, and behavioral changes for the first several hours post-dosing and at least once daily thereafter for up to 14 days after dosing. Observations included gross evaluation of skin and fur, eyes and mucous membranes, respiratory,. circulatory, autonomic and central nervous systems, somatomotor activity and behavior pattern. Particular attention was directed to observation of tremors, convulsions, salivation, diarrhea, and coma.
Individual body weights of the animals were recorded prior to test substance administration (initial) and again on Days 7 and 14 (termination).
- Necropsy of survivors performed: yes
- Other examinations performed: Surviving rats were euthanized via CO2 inhalation at the end of the 14-day observation period. Gross necropsies were performed on all decedents and euthanized animals. The external surface of the body and all orifices, tissues, and organs of the thoracic and abdominal cavities were examined.

Statistics:

The Acute Oral Toxicity (Guideline 425) Statistical Program (Weststat, version 1.0, May 2001) was used for all data analyses including: dose progression selections, stopping criteria determinations and/or LD50 and confidence limit calcuations.

Results and discussion

Effect levels

Sex:

female

Dose descriptor:

LD50

Effect level:

1 030 mg/kg bw

Based on:

test mat.

95% CL:

550 - 1 750

Mortality:

In the 175 mg/kg Dose Level, the animal survived.
In the 550 mg/kg Dose Level, all animals survived exposure to the test substance.
In the 1,750 mg/kg Dose Level, all animals died within two days of test substance administration.

Clinical signs:

other: In the 175 mg/kg Dose Level, the animal appeared active and healthy during the study. There were no signs of gross toxicity, adverse clinical signs, or abnormal behavior. In the 550 mg/kg Dose Level, one animal exhibited hypoactivity, hunched posture, pi

Gross pathology:

In the 175 mg/kg Dose Level, no gross abnormalities were noted for this animal when necropsied at the conclusion of the 14-day observation period.
In the 550 mg/kg Dose Level, no gross abnormalities were noted for any of the animals when necropsied at the conclusion of the 14-day observation period.
In the 1,750 mg/kg Dose Level, gross necropsy of the decedents revealed discoloration of the intestines.

Any other information on results incl. tables

Individual body weights, closes, and mortalities are presented in Table 1. Individual cage-side and necropsy observations are presented in Tables 2 and 3, respectively. Refer to the attachment.

Applicant's summary and conclusion

Interpretation of results:

Toxicity Category IV

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the conditions of this study, the acute oral LD50 of ADTP was estimated to be 1,030 mg/kg of body weight in female rats with an approximate 95% confidence interval, of 550 mg/kg (lower) to 1,750 mg/kg (upper).

Executive summary:

An acute oral toxicity test (Up and Down Procedure) was conducted in accordance with EPA OPPTS 870.1100 (Acute Oral Toxicity) with F344 rats to determine the potential for ADTP to produce toxicity from a single dose via the oral route, Under the conditions of this study, the acute oral LD50 of the test substance was estimated to be 1,030 mg/kg of body weight in female rats with an approximate 95% confidence interval of 550 mg/kg (lower) to 1,750 mg/kg (upper).

A Main Test was conducted using a default starting dose level of 175 mg/kg which was administered to one healthy female rat by oral gavage. Following the up and down procedure, six additional animals were dosed at levels of 550 or 1,750 mg/kg. Females were selected for the test because they are frequently more sensitive to the toxicity of test compounds than males. All animals were observed for mortality, signs of gross toxicity, and behavioral changes at least once daily for up to 14 days after dosing. Body weights were recorded prior to administration, on Days 7 and 14 (termination). Necropsies were performed on all animals.