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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
01 March 1997
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Referenceopen allclose all

Reference Type:
secondary source
Title:
Unnamed
Year:
1997
Report Date:
1997
Reference Type:
publication
Title:
A simple fluorescent staining procedure for micronuclei and RNA in erythrocytes using Hoechst 33258 and pyronin Y
Author:
James T. Mac Gregor et al
Year:
1983
Bibliographic source:
Mutation Research, 120, 269-275
Report Date:
1983

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Principles of method if other than guideline:
- repeated exposure over 14 weeks
GLP compliance:
no
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Analytical purity: 101.7%+-0.6% (functional group titration), equivalent to 89.2%+-0.5% (anhydrous scopolamine hydrobromide) and 11.2%+-0.2% water (Karl Fischer)
- Impurities (identity and concentrations): 0.2% Impurities
- Lot/batch No.: 283- Supplier: Henley and Company, Inc. (New York, NY)

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Simonsen Laboratories, Inc. (Gilroy, CA)- Age at study initiation: 6 or 7 weeks
- Housing: mouse were housed individually
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
ENVIRONMENTAL CONDITIONS
- Temperature: 20 to 24.9°C- Humidity: 45% to 71%
- Air changes (per hr): min. 10 changes per hour- Photoperiod (hrs dark / hrs light): 12/12 dark/light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:0, 15, 45, 135, 400 or 1200 mg scopolamine hydrobromide trihydrate/kg body weight in distilled water by gavage for 14 weeks
Duration of treatment / exposure:
repeated exposure 14 weeks
Frequency of treatment:
repeated exposure 14 weeks
Doses / concentrations
Remarks:
Doses / Concentrations:0, 15, 45, 135, 400 or 1200 mg/kg bwBasis:nominal conc.
No. of animals per sex per dose:
10 male and 10 female mice
Control animals:
yes, concurrent vehicle
Positive control(s):
none

Examinations

Tissues and cell types examined:
Blood
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION:TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields): Peripheral blood samples were obtained from male and female B6C3F1 mice at the end of the 14 week toxicity study.DETAILS OF SLIDE PREPARATION: Smears were immediately prepared and fixed in absolute methanol, stained with a chromatin- specific fluorescent dye mixture of Hoechst 33258/pyronin Y (MacGregor et al., 1983).METHOD OF ANALYSIS: Slides were scanned at 630 or 1000x magnification with a semi-automated image analysis system to determine the frequency of micronuclei in 10000 normochromatic erythrocytes (NCEs) in each of 10 animals per dose group.
Evaluation criteria:
In the micronucleus test an individual trial was considered positive if the trend test P value was less than or equal to 0.025 or the P value for any single exposure group was less than or equal to 0.025 divided by the number of exposure groups.
Statistics:
Testing for increasing trend over exposure groups: one-tailed Cochran-Armitage trend test, followed by pairwise comparisons between each exposure group and the control group

Results and discussion

Test results
Key result
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
not specified

Any other information on results incl. tables

Frequency of Micronuclei in Mouse Peripheral Blood Erythrocytes Following Treatment with Scopolamine Hydrobromide Trihydrate by Gavage for 14 weeksa

   Dose (mg/kg)  Micronucleated NCEs/1000 Cellsb  Number of Mice
 Male      
   0  1.95 +-0.14  10
   15  2.12 +-0.06  10
   45  2.18 +-0.20  10
   135  2.22 +-0.12  10
   400  1.91 +-0.21  10
   1200  2.24 +-0.21  10
 Trend test    P=0.714c  
 Female      
   0  1.59 +-0.09  10
   15  1.43 +-0.11  10
   45  1.64 +-0.14  10
   135  1.43 +-0.09  10
   400  1.40 +-0.12  10
   1200  1.38 +-0.12  10
 Trend test    P=0.1219  

a The detailed scoring protocol is presented by Mac Gregor et al. (1990); 10000 NCEs scored per animal

b Data presented as mean +- standard error of the mean. NCE = normochromatic erythrocyte

c Significance of micronucleated NCEs determined by a one-tailed Cochran-Armitage trend test

Applicant's summary and conclusion

Conclusions:
No increase in the frequency of micronucleated NCEs was noted in peripheral blood samples obtained from male and female mice at the termination of the 14-week toxicity studies with scopolamine hydrobromide trihydrate up to a concentration of 1200 µg/kg bw.