N-methylhyoscinium bromide

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

9 - 11 May 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted for internal use only and hence not conducted in GLP compliance. However, it was conducted by an experienced laboratory and was well described.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The assay was performed according to the instruction manual for the Ames II (Xenometrix, Boulder/USA).

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Methscopolamine bromide

IUPAC Name:

Methscopolamine bromide

Test material form:

other: solid

Details on test material:

- Name of test material (as cited in study report): Methscopolamine bromide
- Physical state: solid

Method

Species / strain

Species / strain / cell type:

bacteria, other: S. typhimurium TA Mix (TA 7001, TA 7002, TA 7003, TA 7004, TA 7005 and TA 7006) and TA 98

Details on mammalian cell type (if applicable):

n/a

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

microsomal liver enzymes from rats (Aroclor 1254-induced)

Test concentrations with justification for top dose:

1, 4, 20, 100, 500, 2500, 5000 μg/mL

Vehicle / solvent:

DMSO

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

2-nitrofluorene

other: 2-aminoanthracene

Details on test system and experimental conditions:

The assay was performed according to the instruction manual for the Ames II (Xenometrix, Boulder/USA). Vehicle, test substance or positive control in a volume of 0.01 mL were incubated with 0.24 mL bacterial overnight culture (ca 107/mL)/exposure medium in 24-well plates for 90 min at 37°C and 250 rpm. With metabolic activation 0.2 mL strain mixture and 0.04 mL S9-mix (30%) were used.

After 90 min the exposed cultures were diluted with pH indicator medium lacking histidine and aliquoted into 48 wells of a 384-well plate (3 replicates) using an 8-channel pipettor. The plates were incubated for 48 hrs at 37°C. To confirm the sensitivity of the tester strains and the metabolic capacity of the S9 fractions, the diagnostic mutagens 2-nitrofluorene (2-NF), 4-nitroquinoline-N-oxide (4-NQO) and 2-aminoanthracene (2-AA) were used, respectively.

Evaluation criteria:

The pH indicator bromocresol purple turns the colour of the cultures from blue to yellow as the pH drops due to the accumulation of catabolites from the metabolic activity of revertant cells. The number of positive wells (yellow) out of a total of 48 wells is an indication of the frequency of reversion per replicate per dose and was compared to the number of spontaneous revertant wells of the solvent control. Each test point contains 48 wells of a 384-well plate. In each 48-well section, the wells were scored for the number of revertant wells (yellow) and the mean value of the triplicates was calculated.

Results and discussion

Test results

Species / strain:

bacteria, other: S. typhimurium TA Mix (TA 7001, TA 7002, TA 7003, TA 7004, TA 7005 and TA 7006) and TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Solubility and Toxicity

Methscopolamine bromide showed neither precipitation nor bacteriotoxicity up to the highest tested concentration of 5000 μg/mL.

Mutagenicity

Methscopolamine bromide did not increase the number of positive wells in the different tester strains neither in presence nor absence of a metabolic activation system compared to the negative control (≤8/48 wells). The vehicle controls showed the expected responses and the positive controls (2-NF, 4-NQO and 2-AA, respectively) showed a clear mutagenic response demonstrating the validity of the

study.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

Methscopolamine bromide (chemical intermediate of BA 679 synthesis) caused neither base-pair substitution nor frameshift mutations in a series of S. typhimurium tester strains (TA Mix and TA 98) in the absence and presence of a metabolic activation system when tested up to recommended concentrations. Therefore, based on these results the test substance can be classified as "Ames II negative".