1-[5-(2,6-difluorophenyl)-4,5-dihydro-1,2-oxazol-3-yl]ethanone

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: OECD Guidelines for Testing of Chemicals, Test No. 406 (1992) JMAFF 12-Nousan-8147 (2000)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Adequate data from an in vivo guinea pig study were available.

Test material

Test material information

Constituent 1

Test material form:

solid

Details on test material:

- Purity: 99.9%

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 3 to 4 weeks
- Weight at study initiation: 371-454 grams at experimental start
- Housing: The animals were gang housed in plastic solid bottom polycarbonate cages or stainless steel solid bottom cages
- Diet: Harlan Teklad Global Guinea Pig Diet® #2040, or equivalent. A designated amount of the diet was available to each guinea pig (approximately 20 grams/day).
- Water: Filtered tap water was supplied ad libitum
- Acclimation period: 5 or 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23°C
- Humidity (%): 56-72%
- Air changes (per hr): 12
- Photoperiod: 12 hour light/dark cycle

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: mineral oil

Induction 2

Concentration / amount:

Induction intradermal injections: test substance in mineral oil (5% w/w)
Induction epicutaneous: test substance in mineral oil 65% w/w

Challenge

Route:

epicutaneous, occlusive

Vehicle:

other: mineral oil

Concentration / amount:

65% w/w mixture in mineral oil or 22% w/w mixture in mineral oil of the test substance

No. of animals per dose:

Test: 20
Control: 10

Details on study design:

RANGE FINDING TESTS: Based on the range finding test, the concentration which produced faint to moderate irritation (1-2) selected for the intradermal induction was a 5% w/w mixture in mineral oil. That which produced very faint to faint irritation selected for the topical induction was a 65% w/w mixture in mineral oil. Due to the lack of significant irritation produced during preliminary topical induction testing, a pretreatment of sodium lauryl sulphate was applied to all animals prior to the topical induction test substance application. The HNIC (the highest concentration that produced responses in four guinea pigs no more severe than two scores of 0.5 and two scores of zero) selected for the challenge phase was a 65% w/w mixture in mineral oil.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures:
Intradermal Phase: two intradermal injections, each at a separate site (0.1 mL each) 5% w/w mixture of test substance in mineral oil or 5% w/w mixture of test substance in an emulsion of Freund’s Adjuvant Complete (50% v/v in distilled water) treated once
Topical Induction Phase: one application, 0.5 g of a 65% w/w mixture of the test substance in mineral oil
-Controls: Emulsion of Freund’s Adjuvant Complete (50% v/v in distilled water); 100% of mineral oil; 50% w/w mixture of mineral oil in an emulsion of Freund’s Adjuvant Complete (50% v/v in distilled water)
- Exposure period:
Intradermal Phase: 6 days
Topical Induction Phase: approximately 14 days
- Site: suprascapular region or flanks
- Frequency of applications: once

B. CHALLENGE EXPOSURE
- No. of exposures: 1; Three occluded topical applications were then placed on all test and test vehicle control group animals using 25 mm Hill Top Chambers. A quantity equal to 0.5 mL of mineral oil was applied to one chamber and positioned on the right middle flank. The remaining two chambers containing 0.5 grams of a 65% w/w mixture of the test substance in mineral oil and 0.5 mL of a 22% w/w mixture in mineral oil were positioned on the left front and rear flank, respectively.
- Day(s) of challenge: After the 24 hour exposure period, the Hill Top exposure chambers were removed and all test sites were gently cleansed of any residual test substance. Approximately 24 and 48 hours after patch removal; these sites were evaluated for a sensitization response (erythema).
- Site: right and left flank of each animal
- Concentrations: 0.5 grams of a 65% w/w mixture of the test substance in mineral oil or 0.5 mL of a 22% w/w mixture in mineral oil
- Control: 0.5 mL of mineral oil
- Evaluation (hr after challenge): 24 and 48 hours

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

all

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

Six test group animals at the 65% dose had a reading of 0.5. One test group animal at the 22% dose had a reading of 0.5. A reading of 0.5 - very faint erythema is not considered a positive reaction by the scoring system.

Remarks on result:

no indication of skin sensitisation

Results 2

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

all

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

One test group animal at the 65% dose had a reading of 0.5. A reading of 0.5 - very faint erythema is not considered a positive reaction by the scoring system.

Remarks on result:

no indication of skin sensitisation

Results 3

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

other: Test Vehicle Control/Naive Animals

Dose level:

all

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

Two test vehicle control/naive animals at the 65% dose had a reading of 0.5. A reading of 0.5 - very faint erythema is not considered a positive reaction by the scoring system.

Remarks on result:

no indication of skin sensitisation

Results 4

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

other: Test Vehicle Control/Naive Animals

Dose level:

all

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none observed

Remarks on result:

no indication of skin sensitisation

Any other information on results incl. tables

All test and vehicle control animals survived, appeared active and healthy and gained body weight during the study. There was no statistical significant difference in the overall body weight gain of the test substance animals as compared to the test substance vehicle control animals.

At the 48 hour Challenge reading the irritation score for the Test Group Animals and Test Vehicle Control/Naive Animals was 0 for 29 of 30 animals. One Test group animal at the 65% dose had a reading of 0.5. A reading of 0.5 - very faint erythema is not considered a positive reaction by the scoring system.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the results of this study, the test substance is considered not to be a contact skin sensitizer.

Executive summary:

A Magnusson-Kligman maximization test was conducted with guinea pigs to determine the potential for the test substance to invoke dermal skin sensitization reactions. The study was conducted using four stages; preliminary irritation screens, a two-stage induction phase, and a challenge phase as described below.

Preliminary irritation testing was performed on animals to determine appropriate concentrations of the test substance that could be used for both intradermal and topical induction as well as topical challenge.

The first induction phase involved six intradermal injections into the suprascapular area of each of 20 guinea pigs. These doses were comprised of pairs of injections of the test substance in mineral oil (5% w/w), the test substance (5% w/w) combined with an emulsion of Freund’s Adjuvant Complete, as well as an emulsion of Freund’s Adjuvant Complete alone. A sham control group (ten animals) was maintained under the same environmental conditions and received injections of mineral oil, mineral oil (50% w/w) combined with an emulsion of Freund’s Adjuvant Complete, as well as an emulsion of Freund’s Adjuvant Complete alone.

Approximately one week later, the second phase of induction was conducted. A 65% w/w mixture of the test substance in mineral oil (test group) or mineral oil (test vehicle control group) was then applied topically for a period of 48 hours to the area encompassing the intradermal injection sites.

Approximately two weeks later, a primary challenge consisting of three occluded applications was conducted on each animal. One Hill Top Chamber containing 0.5 mL of mineral oil was applied to a naive site on the right middle flank of each animal. The remaining two Hill Top Chambers containing 0.5 g of the HNIC (Highest Non-Irritating Concentration, determined in the preliminary irritation screen to be a 65% w/w mixture in mineral oil) of the test substance and 0.5 mL of a 33% dilution of the HNIC (22% w/w mixture in mineral oil) were positioned on two naive sites on the left front and rear flank, respectively, for approximately 24 hours. The test vehicle control group was also treated with the test substance and test vehicle (as described above) at challenge. Approximately 24 and 48 hours after challenge patch removal, all animals were scored for a sensitization response (erythema).

All test and vehicle control animals survived, appeared active and healthy and gained body weight during the study. There was no statistical significant difference in the overall body weight gain of the test substance animals as compared to the test substance vehicle control animals.

At the 48 hour Challenge reading the irritation score for the Test Group Animals and Test Vehicle Control/Naive Animals was 0 for 29 of 30 animals. One Test group animal at the 65% dose had a reading of 0.5. A reading of 0.5 - very faint erythema is not considered a positive reaction. Based on the results of this study, the test substance is considered not to be a contact skin sensitizer.