Imidazo[5,1-f][1,2,4]triazin-4(1H)-one, 2-(2-ethoxyphenyl)-5-methyl-7-propyl-

Endpoint summary

Description of key information

Imidazotriazinon is non toxic after single oral exposure (LD50 cut-off, rat: > 2500 mg/kg bw).

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:

Feb to March 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Winkelmann, Borchen, Germany
- Strain: Hsd Cpb:WU (SPF)
- Age at study initiation: 8-12 weeks
- Mean weight at study initiation: 237 g (males) or 174 g (females)
- Housing: in groups of 3 animals
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 55 +/- 5
- Air changes (per hr): 15-20
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

other: polyethylene glycol 400

Details on oral exposure:

- Application volume: 5 mL/kg bw

- Rationale for the selection of the starting dose:
As described in the flow charts of Annex 2, OECD guideline 423, the starting dose level should be that which is most likely to produce mortality in
some of the dosed animals. Therefore, the limit dose 2000 mg/kg bw was chosen as starting dose.

Doses:

2000 mg/kg

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: at least once daily (clinical signs, mortality) or once weekly (weight gain)
- Necropsy of survivors performed: yes

Statistics:

none (limit test)

Sex:

male/female

Dose descriptor:

other: LD50 cut-off

Effect level:

> 2 500 mg/kg bw

Based on:

test mat.

Mortality:

One male and one female animal died after administration of 2000 mg/kg bw.

Clinical signs:

other: After administration of 2000 mg/kg bw in both genders the motility and reactivity were decreased, the gait uncoordinated, the palpebral fissures narrowed and the breathing labored. Additionally, in females piloerection occurred and one animal lay in abdom

Gross pathology:

No gross pathological findings were observed.

Other findings:

none

Executive summary:

The acute oral toxicity of the test substance was low with an LD50 exceeding 2500 mg/kg bw in rats (cut-off value) according to OECD TG 423. At the limit-dose of 2000 mg/kg bw one male and one female animal died and in both genders clinical signs were observed up to day 3 after administration. The main clinical findings were decreased motility, decreased reactivity, uncoordinated gait, narrowed palpebral fissures and labored breathing. Administration was tolerated without effects on body weight gain and gross pathological findings.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 500 mg/kg bw

Quality of whole database:

The study is GLP compliant and is of high quality (Klimisch score=1)

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The acute oral toxicity of Imidazotriazinon was low with an LD50 exceeding 2500 mg/kg bw in rats (cut-off value) according to OECD TG 423 (Krötlinger, 2000). At the limit-dose of 2000 mg/kg bw one male and one female animal died and in both genders clinical signs were observed up to day 3 after administration. The main clinical findings were decreased motility, decreased reactivity, uncoordinated gait, narrowed palpebral fissures and labored breathing. Administration was tolerated without effects on body weight gain and gross pathological findings.

Justification for selection of acute toxicity – oral endpoint
Only one study available

Justification for classification or non-classification

Based on the study results a classification according to Directive 67/548/EEC or Regulation (EC) No. 1272/2008 (CLP) is not warranted.