N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-3-oxobutyramide

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: well performed OECD and GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

yes

Remarks:

The relative humidity in the animal room was between approximately 30-83%. This deviation to the study plan, however, did not affect the validity of the study.

GLP compliance:

yes

Remarks:

.

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-3-oxobutyramide

EC Number:

247-820-7

EC Name:

N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-3-oxobutyramide

Cas Number:

26576-46-5

Molecular formula:

C11H11N3O3

IUPAC Name:

3-oxo-N-(2-oxo-2,3-dihydro-1H-benzimidazol-5-yl)butanamide

Details on test material:

- Name of test material (as cited in study report): Acetolon TTR

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

Source: Harlan Netherlands, B.V. Postbus 6174, NL - 5960 AD Horst / Netherlands
Age: 8 - 12 weeks (beginning of acclimatisation)
Identification: Single caging. The animals will be distributed into the test groups at random and identified by cage number
Accimatisation: Under test conditions after health examination. Only animals without any visible signs of illness will be used for the study.

Housing: single
Cage type: Makrolon Type I, with wire mesh top (Ehret GmbH, D-79302 Emmendingen)
Bedding: granulated soft wood bedding (Harlan Winkelmann GmbH, D-33178 Borchen)
Feed: pelleted standard diet, ad libitum (Harlan Winkelmann GmbH, D-33178 Borchen)
Water: tap water, ad libitum (Gemeindewerke, D-64380 Roßdorf)
Environment: temperature: 22 +/- 3 °C
relative humidity: 30-83 %
artificial light 6.00 a.m. - 6.00 p.m.

Study design: in vivo (LLNA)

Vehicle:

dimethyl sulphoxide

Concentration:

3 concentrations: 2.5, 5.0 and 10.0 % (w/v)

No. of animals per dose:

4 animals per group

Details on study design:

RANGE FINDING TESTS:
To determine the highest non-irritant and technically applicable test item concentration, a pretest was performed in two mice with concentrations of 1.0, 2.5, 5.0, and 10.0 % (w/v)

MAIN STUDY:
Each test group was treated by topical (epidermal) application to the dorsal surface of each ear lobe with different test item concentrations of 2.5, 5.0 and 10.0 % (w/v) in DMSO.
Application volume: 25 µl
Surface diameter: ca. 8 mm
Application: once daily for 3 consecutive days. A hair dryer was used to dry the ear's surface as quickly as possible to avoid loss of test item applied.

Five days after the first topical application, all mice were adminitered with 250 µl of 79.4 µCi/ml 3HTdR (corresponds to 19.9 µCi 3HTdR per mouse) by intravenous injection via a tail vein.

A test item is regarded as a sensitizer in the LLNA if the following criteria are fulfilled:
- First, that exposure to at least one concentration of the test item resulted in an incorporation of 3HTdR at least 3-fold or greater than that recorded in control mice, as indicated by the stimulation index.
- Second, that the data are compatible with a conventional dose response, although allowance must be made (especially at a high topical concentrations) for either local toxicity or immunological suppression.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

A statistical analysis was conducted for assessment of the dose-response relationship, and the EC3 value was calculated according to the equation:
EC3 = (a-c)[(3-d)/(b-d)]+c
EC3: estimated concentration of the test item required to produce a 3-fold increase in draining lymph node cell proliferative activity
a,b, and c,d are respectively the co-ordinates of the two pair of data lying immediately above and below the S.I. value of 3 on the local lymph node assay dose response plot.

Results and discussion

Positive control results:

EC3 = 9.9 % (w/v) (No. 860600, October 2004)
EC3 = 6.3% (w/v) (April 2004)

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: Test group 2 (2.5%): 1.78 Test group 3 (5.0%): 1.63 Test group 4 (10.0%): 1.26

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Group: Background I: 3.1 Background II: 0.0 Control group 1: 3118.2 Test group 2 (2.5%): 5544.9 Test group 3 (5.0%): 5086.8 Test group 4 (10.0%): 3938.7

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

The test item is found to be not a skin sensitiser in this assay, since none of the test item concentrations caused a 3-fold or greater increase in incorporation of 3HTdR compared with concurrent controls, as indicated by the stimulation index.

Executive summary:

In the study the test item Acetolon TTR dissolved in DMSO was assessed for its possible contact allergenic potential.

For this purpose a local lymph node assay was performed using test item concentrations of 2.5, 5.0, and 10.0 %.

The animals did not show any clinical signs during the course of the study and no cases of mortality were observed.

In this study Stimulation Indices (S.I.) of 1.78, 1.63, and 1.26 were determined with the test item at concentrations of 2.5, 5.0, and 10.0 % (w/v) in DMSO.

The test item Acetolon TTR was found to be not a skin sensitiser in this assay.