N-(1,1,3,3-tetramethylbutyl)acrylamide

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP study, but no guideline was followed

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Principles of method if other than guideline:

The test did not follow the official testing guidelines. The study was conducted in different phases. In a first phase, five males and five females were exposed to steadily increasing doses of the test substance over a period of 14 days. The initial dose was 200 mg/kg from day 1 to 4, which was increased to 400 mg/kg on days 5 to 7, 600 mg/kg on days 8 to 11 and 1000 mg/kg on days 12 to 14. In a second phase, five males and five females were exposed to 1000 mg/kg once. In a following trial phase three males and three females were exposed to 750 mg/kg on three subsequent days. In phase 4, five males and five females were exposed to an initial dose of 600 mg/kg on day 1, but due to severe clinical signs exposure was suspended on day 2, and all animals were exposed to 400 mg/kg from days 3 to 14. In a final phase, a new vehicle was tested and two males and two females each were exposed to 200 mg/kg from days 1 to 14, 300 mg/kg from days 3 to 14, 500 mg/kg from days 5 to 8, 600 mg/kg from days 7 to 9 or to vehicle on days 1 to 9 and 400 mg/kg from days 10 to 14.

GLP compliance:

yes

Test type:

other: see Principles of method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

N-(1,1,3,3-tetramethylbutyl)acrylamide

EC Number:

224-169-7

EC Name:

N-(1,1,3,3-tetramethylbutyl)acrylamide

Cas Number:

4223-03-4

Molecular formula:

C11H21NO

IUPAC Name:

N-(1,1,3,3-tetramethylbutyl)acrylamide

Test material form:

solid: pellets

Details on test material:

- Name of test material (as cited in study report): Octylacrylamide 27-8098
- Analytical purity: 100%
- Impurities (identity and concentrations): not applicable
- Purity test date: 13 November 2003
- Lot/batch No.: 90360313
- Expiration date of the lot/batch: 31 December 2004

Test animals

Species:

rat

Strain:

other: Crl:WI(GLX/BRL/Han)IGSBR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River UK Ltd, Margate, UK
- Age at study initiation: MTD I/Fixed dose I phase animals were approximately 6 weeks old, Fixed dose II phase animals were about 5 weeks old, MTD II phase animals were about 11 weeks old
- Weight at study initiation: MTD I/Fixed dose I males weighed 160.7 to 203.3 g, MTD I/Fixed dose I females weighed 135.4 to 156.5 g, Fixed dose II males weighed 97.1 to 124.6 g and females weighed 96.1 to 102.3 g, MTD II males weighed 252.5 to 295.1 g and females weighed 188.9 to 212.7 g.
- Fasting period before study:
- Housing:
- Diet (e.g. ad libitum):
- Water (e.g. ad libitum):
- Acclimation period:

ENVIRONMENTAL CONDITIONS
- Temperature (°C):
- Humidity (%):
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light):

IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 1% (w/v) aqueous carboxymethyl cellulose plus 0.5% Tween 80 (added from day 5 on); in the second phase of maximum tolerable dose testing, 5% (v/v) ethanol in corn oil was used

Details on oral exposure:

VEHICLE
- Concentration in vehicle: as required
- Amount of vehicle (if gavage): as required
- Justification for choice of vehicle: chosen in conjunction with the sponsor

MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg for the carboxymethyl cellulose/Tween 80 formulations and 5 mL/kg for the ethanol/corn oil formulations

DOSAGE PREPARATION (if unusual): test article was weighed, transferred to a mortar and pestle and mixed to a smooth paste with some of the measured vehicle and then transferred to a bottle. The remaining vehicle was used to rinse the mortar and pestle and added to the formulation to make up the final volume. A blender was used to ensure homogeneity. For the preparation of doses in 5% ethanol in corn oil the material was weighed into a beaker. The test substance and corn oil were warmed, the required volume of ethanol was added to the test substance and stirred to aid dissolution. The formulation was then transferred to a measuring cylinder, made up with the required volume of warmed corn oil and stirred.

Doses:

Maximum tolerated dose (MTD), phase I: 200 to 1000 mg/kg/day
Fixed dose, phase I: 1000 mg/kg
Trial: 750 mg/kg/day
Fixed dose, phase II: 600 mg/kg on day one, then 400 mg/kg/day on days 3 to 14
Maximum tolerable dose (MTD), phase II: either 200, 300, 400, 500 or 600 mg/kg/day

No. of animals per sex per dose:

Maximum tolerated dose (MTD), phase I: five
Fixed dose, phase I: five
Trial: two
Fixed dose, phase II: five
Maximum tolerable dose (MTD), phase II: two

Control animals:

yes

Details on study design:

- Duration of observation period following administration: animals were exposed and observed for up to 14 days, depending on the group
- Observations and frequencies: CLINICAL OBSERVATIONS - cage side, twice daily for morbidity and mortality; POST-DOSE OBSERVATIONS - immediately, 0.5, 1, 2 and 4 hours after exposure and additionally on occasions; BODY WEIGHTS - once weekly during pre-dose period, before dosing on the day of each incremental change in dose during MTD I phase, on day one of Fixed dose I phase, on days 1 and 3 of trial phase and days 1, 2, 3, 4, 7, 8 and 1 during Fixed dose II phase and daily during MTD II phase; FOOD INTAKE - determined over each incremental dose perido during MTD I phase and over days 1-3, 4-6, 7-10 and 11-13 of the Fixed dose II phase and daily during MTD II phase; CLINICAL PATHOLOGY - samples taken from Fixed dose II animals at scheduled necropsy, collected from abdominal aorta ater overnight period without food; ANATOMIC PATHOLOGY - necropsy was performed with all animals except those of the trial phase, organ weights were weighed from MTD, Fixed dose I and Fixed dose II phase animals, tissues were preserved in appropriate fixatives from necropsied animals except those from MTD II phase

Statistics:

No statistics due to small group sizes

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

other: NOAEL

Effect level:

300 mg/kg bw

Based on:

test mat.

Mortality:

Not during MTD I phase; all animals of the Fixed dose I phase were killed on the first day of dosing due to severe clinical signs; no mortality occurred during the trial phase; one female given 600 mg/kg/day was killed on day 1, one male was found dead on day 8 of dosing at 400 mg/kg/day and two males were killed due to severe clinical signs on day 8 of dosing of the Fixed dose II phase; one male given 500 mg/kg/day was killed due to severe clinical signs on day 3 of dosing, one male given 600 mg/kg/day was killed on day 3 of dosing and one female was killed on day 4 of dosing of the MTD II phase

Clinical signs:

other: MTD phase I: no clinical findings Fixed dose phase I: all animals were killed on the first day of dosing due to severe clinical signs such as convulsions, tremors, prostration, cold and hunched posture; laboured respiration and semi-closed eyes were obser

Gross pathology:

MTD phase I: no findings during necropsy
Fixed dose phase I: all animals were killed on the first day of dosing
Trial phase: not performed
Fixed dose phase II: unscheduled deaths might have been the result of dose formulation being inhaled into the lungs
MTD phase II: no findings

Other findings:

MTD phase I: food intakes were slightly lower than in control group from day 8 of dosing onwards (in rats receiving 600 or 1000 mg/kg/day)
Fixed dose phase I: all animals were killed on the first day of dosing
Trial phase: not reported
Fixed dose phase II: haematological parameters and clinical chemistry data were within the expected ranges for animals of this strain and age
MTD phase II: not reported

Applicant's summary and conclusion

Interpretation of results:

other: Information inappropriate to conclude on classification; NOAEL (14-day period) = 300 mg/kg bw/day

Conclusions:

Adverse effects of treatment including death, post-dosing signs of subdued behaviour, ataxia and tremors and lower body weight gain and food intake were observed in animals given 400 mg/kg/day N-tert-octylacrylamide and above over periods of up to 14 days. The NOAEL was 300 mg/kg/day.

Executive summary:

The purpose of the study was to determine the maximum tolerated dose of the substance N-tert-octylacrylamide following oral administration to the rat by oral gavage and to assess the toxicity of repeated administration at this dose level using naive animals for 14 days. The study was conducted under GLP using male and female Crl:WI(GLX/BRL/Han) IGSBR rats. The maximum tolerable dose was tested in a stepwise procedure. Five males and five females received repeated oral doses of the substance starting with 200 mg/kg/day over 4 days, then increasing to 400 mg/kg/day for 3 days, to 600 mg/kg/day for four days and finally to 1000 mg/kg/day for three days. There were no deaths or clinical signs and no necropsy findings. In a second phase, a fixed dose of 1000 mg/kg/day was tested with five males and females. However, due to severe clinical signs all animals were killed on the first day of dosing. A trial was then performed with two males and females receiving 750 mg/kg for three days. In a second fixed dose phase, five males and five females received 600 mg/kg/day on the first day of dosing. Dosing was suspended on the second day and reduced to 400 mg/kg/day from day 3 to 14 of dosing because of severe clinical signs. In a final step, a second maximum tolerated dose phase was conducted and animals received between 200 and 600 mg/kg/day for varying periods of time.

In conclusion, adverse effects of treatment, including death, post-dosing signs of subdued behaviour, ataxia and tremors and lower body weight gain and food intake were noted in animals given 400 mg/kg/day N-tert-octylacrylamide and above for periods of up to 14 days. The NOAEL was considered to be 300 mg/kg/day.