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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Although the study was conducted according to GLP and well documented methods, " Practical guide 10: How to avoid unnecessary testing on animals", Section 3.3.2 states it is important that the reliability indicator (Klimisch score) reflects the assumptions of similarity. Thus, a score of 1 (reliable without restrictions) should normally not be used for results derived from read-across.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1988
Report Date:
1988

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: Ames-88, Edition 5
Principles of method if other than guideline:
Substance was testest for mutagenic activity in Salmonella typhimurium strains TA1535, TA97, TA98, and TA100, with and without activiation.
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report):1H-imidazole-5-methanol, 2-butyl-4-chloro-1-[2'-(1H-tetrazol-5-y1)[1,1'-biphenyl]-4-ylmethyl]-, potassium salt

- Substance type:
- Physical state:

- Analytical purity: 99.5%

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535
Species / strain / cell type:
S. typhimurium TA 97
Species / strain / cell type:
S. typhimurium TA 98
Species / strain / cell type:
S. typhimurium TA 100
Metabolic activation:
with and without
Metabolic activation system:
S9
Test concentrations with justification for top dose:
0, 67, 135, 673, 1000, 5000 micrograms/plate
Controls
Untreated negative controls:
yes
Remarks:
distilled-deionized water
Negative solvent / vehicle controls:
no
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
2-nitrofluorene
sodium azide
other: 2-aminoanthracene
Details on test system and experimental conditions:
PLATE INCORPORATION ASSAY

The assay was perfomre din the presence and the absence of a rat liver homogenate activation system (S-9 mix) similar to the method described by Ames et al (Mutation Res.113:173-215, 1983). All tester strains were obtained from Dr. B. Ames, Berkeley, CA. Positive indicators and negative controls were included in all assays. Treatments without activation (nonactivated) were conducted by adding 0.1 mL of the solvent or a solution of DuP 753 and 0.1 mL of an overnight culture containing approximately 10^8 bacteria to 2mL of top agar (0.6% agar, 0.6% NaCl, 0.05 mM L-histidine, 0.05 mM biotin). These components were mixed and poured on the surface of a plate containing 25mL of Davis minimal agar. Treatments with activation were conducted by adding 0.5 mL of S-9 mix to the bacteria/test sample/top agar as described above and pouring the mixture onto a minimal agar plate. The S-9 mix contained per mL: 0.3 mL of S-9 diluted to 5.6 mg/mL with phosphate buffered saline (PBS), and 0.7 mL of a cofactor solution containing 8 micromoles MgCl2, 33 micormoles KCl, 5 micromoles glucose-6-phosphate, 4micromoles NADP and 100 micromoles sodium phosphate (pH 7.4). The S-9 (Sitek Research Laboratories, Rockville, MD Lot 871215) was the 9000xg supernatant of liver homogenate (1g wet liver : 3.0mL PBS). The livers were obtained from 8 to 9 week old male Crl:CD BR (Charles River, Kingston, NY) rats injected intraperitoneally with Aroclor 1254 (500 mg/kg) 5 days before sacrifice. The revertant colonies were counted after the individually labelled plates were incubated at 37 deg C for 48 hours.
Evaluation criteria:
Classification Guidelines:

Positive:
A. The average number of induced revertants at one more of the test sample concentrations studied is at least two times greater than the average number of revertants in the solvent control.

And

B. There is a dose response relationship

Negative:
A. Average number of induced revertants at each concentration is similar to the average number of revertants in the solvent control.
OR
B. There is no dose-response relationship.

Equivocal:
Neither of the criteria for a positive or negative is satisfied.
Statistics:
Doses with and without activation were ranked and results from a strain were analysed individually by multiple linear regression. Comparison were made between each dose/concentration and the solvent control (0 rank), using the mean square error estimate. All comparisons were at the 95% level of confidence (alpha=0.05).

Results and discussion

Test results
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Additional information on results:
DuP 753 was tested for cytotoxicity in Salmonella typhimurium strain TA98 with and without activation. DuP 753 exhibited no toxicity to strain TA 98 without or with activaition at dose levels of 5000 ug/plate. Based on these results, 5000 ug/plate with and without activation were chosen as the highest doses for mutagenicity assays.

DuP 753 was tested for mutagenicity activity in Salmonella typhimurium strains TA1535, TA97, TA98 and TA100 with and without activation. No mutagenic activity was detected in any strain either with or without activation at dose levels up to 5000 ug/plate. Under the conditions of this assay, DuP 753 is negative.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Concentration μg/plate

Colonies/plate w/o activation

Colonies/plate w/activation

0

1743, 1644

1791, 1800

67

1779, 1729

1795, 1827

135

1723, 1773

1842, 1854

673

1695, 1759

1785, 1855

1000

1782, 1903

1781, 1784

5000

1688, 1818

1704, 1679

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

Under the conditions of this assay, DUP 753 (losartan potassium) is negative. Therefore, by read-across, losartan free acid is negative for mutagenicity.
Executive summary:

DUP 753 was testest for mutagenic activity in Salmonella typhimurium strains TA1535, TA97, TA98, and TA100, with and without activiation. Results of the mutagenicity trials are shown in Tables II thorugh IX. No mutagenic activity was detected in any strain either with or without activation at dose levels up to 5000 micrograms / plae. Under the conditions of this assay, DUP 753 is negative.