6-ethyl-5-fluoro-4(3H)-pyrimidone

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 1996-05-29 to 1996-06-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

OJ No. L383A, 29.12.92

Deviations:

no

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

Testing performed in the nineties, and conducted in accordance with the test methods laid down in EC and in compliance with the principles of good laboratory practice of EC, OECD, etc.

Test material

Test material information

Constituent 1

Reference substance name:

6-ethyl-5-fluoro-4(3H)-pyrimidone

EC Number:

422-460-5

EC Name:

6-ethyl-5-fluoro-4(3H)-pyrimidone

Cas Number:

137234-87-8

Molecular formula:

C6 H7 F N2 O

IUPAC Name:

6-ethyl-5-fluoro-3,4-dihydropyrimidin-4-one

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Batch No.: 950704
Purity: 95.7%

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: D. Hall, Newchurch, Staffordshire, England.
- Age at study initiation: Ca. five to six weeks
- Weight at study initiation: 357-427 g
- Housing: housed in groups of five in suspended metal cages with wire mesh floors
- Diet: vitamin C enriched guinea-pig diet FD2, ad libitum; Hay was given weekly.
- Water: ad libitum
- Acclimation period: six days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21
- Humidity (%): 30-70
- Air changes (per hr): 15 air changes per hour approximately
- Photoperiod (hrs dark / hrs light): 12 hours of artificial light (0700 - 1900 hours) in each 24 hours period.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal

Vehicle:

water

Concentration / amount:

2.5% w/v

Day(s)/duration:

Day 1

Adequacy of induction:

highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically

Induction 2

Route:

other: Topical, otherwise unspecified

Vehicle:

water

Concentration / amount:

70% w/v

Day(s)/duration:

Day 8 / 48 h

Adequacy of induction:

non-irritant substance, but skin pre-treated with 10% SDS

Challenge

Challenge 1

No.:

#1

Route:

other: Topical, not specified

Vehicle:

water

Concentration / amount:

70% w/v

Day(s)/duration:

Day 22 / 24h

Challenge 2

No.:

#2

Route:

other: Topical, not specified

Vehicle:

water

Concentration / amount:

35% w/v

Day(s)/duration:

Day 22 / 24 h

No. of animals per dose:

Test: 10
Control: 5

Details on study design:

RANGE FINDING TESTS:
The intradermal and topical irritancy of a range of dilutions of the test substance was investigated to identify where possible (a) concentrations of the test substance that would produce irritation suitable for the induction phase of the main study and (b) a maximum non-irritant concentration by the topical route of administration for the challenge phase.

MAIN STUDY
A. INDUCTION EXPOSURE
- Induction intradermal injections - test animals:
A 40 x 60 mm area of dorsal skin on the scapular region of the guinea-pig was clipped free of hair with electric clippers. Three pairs of intradermal injections were made into a 20 X 40 mm area within the clipped area.
Injectables for the test animals were prepared as follows:
1. Freund's complete adjuvant was diluted with an equal volume of water for irrigation (Ph.Eur.).
2.test item, 2.5% w/v in water for irrigation.
3. test item, 2.5% w/v in a 50 : 50 mixture of Freund's complete adjuvant and water for irrigation.

- Induction topical application - test animals:
Six days after the injections, the same 40 x 60 mm interscapular area was clipped and shaved free of hair and the site was pre-treated by gentle rubbing with 0.5 mL per site of 10% w/w sodium lauryl sulphate in petrolatum. Twenty-four hours later a 20 x 40 mm patch of Whatman No. 3 paper was saturated with approximately 0.4 mL of test item, 70% w/v in distilled water. The patch was placed on the skin of the test animals and covered by a length of impermeable plastic adhesive tape (50 mm width "Blenderm"). This in turn was firmly secured by elastic adhesive bandage (50 mm width "Elastoplast") wound round the torso of the animal and fixed with "Sleek" impervious plastic adhesive tape. The dressing was left in place for 48 hours.

- Induction - control animals: Treated similarly to the test animals with the exception that the test substance was omitted from the intradermal injections and topical application.

B. CHALLENGE EXPOSURE
- Day(s) of challenge: two weeks after the töpical induction
- Exposure period: 24 h
- Test and control groups: Hair was removed by clipping and then shaving from an area on the left flank of each guinea-pig. A 20 x 20 mm patch of Whatman No. 3 paper was saturated with approximately 0.2 ml of UK-103,442, 70% w/v in distilled water and applied to an anterior site on the flank. The test item, 35% w/v in distilled water was applied in a similar manner to a posterior site. The patches were sealed to the flank for 24 hours under strips of "Blenderm" covered by "Elastoplast" wound round the trunk and secured with "Sleek".
- Concentrations: 70 and 35% w/v in distilled water
- Evaluation: 24 and 48 hours after removal of the patches

OTHER:
- Clinical signs: All animals were observed daily for signs of ill health or toxicity.
- Bodyweight: recorded on Day 1 (day of intradermal injections) and on the last day observations were made of dermal responses to the challenge applications.

Positive control substance(s):

yes

Remarks:

The sensitivity of the guinea-pig strain used is checked periodically at lab with hexyl cinnamic aldehyde, a known sensitiser.

Results and discussion

Positive control results:

10/10 animal give positive result at the most recently test.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

35 and 70% w/v

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No signs of ill health or toxicity recorded

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

35 and 70% w/v

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No signs of ill health or toxicity recorded

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

35 and 70% w/v

No. with + reactions:

0

Total no. in group:

5

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

35 and 70% w/v

No. with + reactions:

0

Total no. in group:

5

Results 5

Reading:

other: Not specified

Group:

positive control

Dose level:

As supplied and 50 % v/v

No. with + reactions:

10

Total no. in group:

10

Remarks on result:

positive indication of skin sensitisation

Any other information on results incl. tables

- Bodyweight:

Bodyweight increases were recorded for all guinea-pigs over the period of the study.

 

INDUCTION

-Intradermal injections:

Necrosis was recorded at sites receiving Freund's Complete Adjuvant in test and control animals.

Slight irritation was seen in test animals at sites receiving test item, 2.5% w/v in water for irrigation and no irritation was observed in control animals receiving water for irrigation.

- Topical application:

Moderate erythema was observed in test animals following topical application with test item, 70% w/v in distilled water. Slight erythema was seen in the control guinea-pigs.

 

CHALLENGE

There were no dermal reactions seen in any of the test or control animals.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In this study, the test item did not produce evidence of skin sensitisation (delayed contact hypersensitivity) in any of the ten test animals.

Executive summary:

This study was performed to assess the skin sensitisation potential of test item using the guinea pig following the method as described in EC B.6. Ten test and five control guinea-pigs were used in this study. The dose levels selected was 2.5 %w/v in water for Intradermal injection, 70% w/v in distilled water for Topical application, 70 and 35% w/v in distilled water for Challenge application.

In this study, the test item did not produce evidence of skin sensitisation (delayed contact hypersensitivity) in any of the ten test animals.