Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
03 March 1986 to 22 September 1986
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP compliant, guideline study, available as unpublished report, no restrictions, fully adequate for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Two part main experiment: In the first part a single dose of 5000 mg/kg was administered to 3 groups of 8 male and 8 female Chinese hamsters. The groups were killed after 16, 24, and 48 hours. Three same sized negative control groups were treated with the vehicle and also killed after 16, 24, or 48 hours. The sensitivity of the test system was checked by treating one further group with 64 mg/kg of the known mutagen Cyclophosphamide (CPA). The animals of this group were killed 24 hours after treatment. Analytical purity: 93.9%

In the second part three groups of 8 male and 8 female hamsters were treated with a single dose of 1250, 2500, or 5000 mg/kg of CGA 154281 and killed after 24 hours. Negative and positive control groups were used. After sacrifice the bone marrow from the shafts of both femurs was removed and smears were prepared on slides. Routinely the slides of five animals/sex/dose were stained with May-Grunwald solution and scored for micronuclei. As an exception, the slides from 3 males and 7 females which were killed after 16 hours (part 1) were scored, since only three males in each group furnished well differentiated cells. From each animal the ratio of polychromatic to normochromatic erythrocytes was determined as an indicator for toxic effects on the erythropoiesis and 1000 polychromatic erythrocytes were scored for micronuclei.
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
hamster, Chinese
Strain:
other: Random outbred strain
Sex:
male/female
Details on test animals and environmental conditions:
3 groups each consisting of 8 male and 8 female Chinese hamsters.
TEST ANIMALS
- Age at study initiation: females 6-10 weeks, males 4-9 weeks
- Weight at study initiation: females 22-32 g, males 20-35 g
- Diet: NAFAG No.924
- Water: Tap water ad libitum
- Acclimation period: 4-5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22-23°C
- Humidity: 52-59%
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 03 March 1986 To: 22 September 1986

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
0.5% aqueous carboxymethylcellulose (CMC).
Details on exposure:
Part 1: The different groups of animals were killed after 16, 24, and 48 hours.
Part 2: The different groups of animals were killed after 24 hours.
Duration of treatment / exposure:
16 to 48 hours
Frequency of treatment:
Single dose
Post exposure period:
None.
Doses / concentrations
Remarks:
Doses / Concentrations:
1250, 2500 or 5000 mg/kg
Basis:
nominal conc.
No. of animals per sex per dose:
8
Control animals:
yes, concurrent vehicle
Positive control(s):
Cyclophosphamide (CPA)
- Route of administration: oral gavage
- Doses / concentrations: 64 mg/kg

Examinations

Tissues and cell types examined:
After sacrifice the bone marrow from the shafts of both femurs was removed and smears were prepared on slides.

Details of tissue and slide preparation:
Routinely the slides of five animals/sex/dose were stained with May-Grunwald solution and scored for micronuclei. As an exception, the slides from 3 males and 7 females which were killed after 16 hours (part 1) were scored, since only three males in each group furnished well differentiated cells.
Evaluation criteria:
From each animal the ratio of polychromatic to normochromatic erythrocytes was determined as an indicator for toxic effects on the erythropoiesis and 1000 polychromatic erythrocytes were scored for micronuclei.
Statistics:
Chi-Square test used

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
In both parts of the main experiment all hamsters survived. At all sampling times (16, 24, and 48 hours) and at all dose levels (5000, 2500, and 1250 mg/kg) no statistically significant increase of micronucleated polychromatic erythrocytes (PCEs) was observed when compared to the negative control. In the positive control groups the percentage of micronucleated PCEs was statistically significant increased, thus demonstrating the sensitivity of the test system.

Any other information on results incl. tables

Chinese hamster micronucleus test

Part 1: Percentage of micronucleated PCEs at different preparation times

Test article and concentration

Sex

16 hours

24 hours

48 hours

CGA154281

(5000 mg/kg)

males

females

mean

0.07

0.06

0.06

0.00

0.08

0.04

0.06

0.06

0.06

Negative control – vehicle

(0.5% CMC)

males

females

mean

0.07

0.04

0.05

0.04

0.04

0.04

0.10

0.04

0.07

Positive control – cyclophoshamide

(64 mg/kg)

males

females

mean

 

3.68

5.46

4.57*

 

* p>0.05 (Chi-Square test)

Chinese hamster micronucleus test

Part 2: Percentage of micronucleated PCEs at different dose levels sacrificed after 24 hours

Sex

CGA154281

1250 mg/kg

CGA154281

2500 mg/kg

CGA154281

5000 mg/kg

Negative control

0.5% CMC

Positive control

64 mg/kg CPA

Males

Females

Mean

0.02

0.00

0.01

0.04

0.02

0.03

0.04

0.06

0.05

0.08

0.02

0.05

2.00

1.58

1.79*

* p > 0.05 (Chi-Square Test)

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Under the given experimental conditions no evidence for a clastogenic or aneugenic activity of CGA154281 was observed in vivo.
Executive summary:

CGA154281 technical, Benoxacor, was administered by gavage to Chinese hamsters to evaluate any mutagenic activity on polychromatic erythrocytes in bone marrow cells, in vivo. In the first experiment the highest dose of 5000 mg/kg was administered and animals sacrificed 16, 24 or 48 hours later. In the second assay, doses of 1250, 2500 and 5000 mg/kg were administered and animals sacrificed after 24 hours exposure.

In the first assay, bone marrow smears showed no significant increase in micronucleated polychromatic erythrocytes.

In the second assay, bone marrow smears showed no significant increase in micronucleated polychromatic erythrocytes.

No evidence of mutagenic effects were found in the Chinese hamster after oral administration of Benoxacor.