Ibuprofen

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1987-05-26 to 1987-06-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

(1981)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Test was conducted before LLNA test guideline was implemented.

Test material

Test material information

Constituent 1

Reference substance name:

Ibuprofen

EC Number:

239-784-6

EC Name:

Ibuprofen

Cas Number:

15687-27-1

Molecular formula:

C13H18O2

IUPAC Name:

2-(4-isobutylphenyl)propanoic acid

Details on test material:

- Name of test material (as cited in study report): Ibuprofen Gel 10%
- Physical state: smooth white opaque gel
- Analytical purity: 10.3% (w/w)
- Impurities (identity and concentrations): phenoxyethanol, 1.06 % (w/w)
- Purity test date: 1987-13-05
- Lot/batch No.: IC11/3
No further data.

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Interfauna (UKI Limited, Wyton, Huntingdon, Cambridgeshire
- Age at study initiation: 8 - 10 weeks
- Weight at study initiation: 320 - 398 g
- Housing: groups of up to 4, solid-floor polypropylene cages furnished with softwood shavings
- Diet (ad libitum): Guinea Pig FD1 Diet, Special Diet Services Limited, Witham, Essex, U.K.
- Water (ad libitum): tap water
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-25°C
- Humidity (%): 55-68%
- Air changes (per hr): ca. 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: no data

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: arachis oil, Freund's Complete Adjuvant, or no additional vehicle

Induction 2

Concentration / amount:

Intradermal Induction : 5% (w/v), i.e. 0.5 % active substance
Topical Induction: undiluted as supplied, i.e. 10 % active substance
Topical Challenge: undiluted as supplied, i.e. 10 % active substance

Challenge

Challenge 1

Route:

epicutaneous, semiocclusive

Vehicle:

other: arachis oil, Freund's Complete Adjuvant, or no additional vehicle

Challenge 2

Concentration / amount:

Intradermal Induction : 5% (w/v), i.e. 0.5 % active substance
Topical Induction: undiluted as supplied, i.e. 10 % active substance
Topical Challenge: undiluted as supplied, i.e. 10 % active substance

No. of animals per dose:

20 test animals
20 control animals

Details on study design:

1st application: Induction 0.5 % active substance intracutaneous
2nd application: Induction 10 % active substance occlusive epicutaneous
3rd application: Challenge 10 % active substance semiocclusive

RANGE FINDING TESTS:
Selection of the concentration for intradermal induction:
In a group of four, one animal was applied the test material, Ibuprofen gel 10%, at concentrations of 1, 5, 10, and 25% (w/v) in arachis oil, respectively. Injection sites were read at 24, 48, and 72 h and 78 days after injection.
No evidence of necrosis was observed with 1 and 5%. With 10%, necrosis and eschar formation was noted after 72 h and 7 days, respectively. With 25% necrosis was evident at 24, 48, and 72 h; eschar formation was noted at 7 days. There was no evidence of systemic toxicity in any animal of this group at any time.
According to the authors, based on these result, a concentration of 5% (w/v) was selected for the intradermal induction in the main test.

Selection of the concentration for topical application:
In a group of four, each animal was applied the test material, Ibuprofen gel 10%, both undiluted and as a 75% (w/v) dilution in distilled water (no further information). Skin sites were read at 1, 24, and 48 h after removal of the test patches.
With the undiluted test material, scattered mild redness (Draize score 1) and moderate/diffuse redness (Draize score 2) was observed in 3 and 1 animal(s), respectively at 1 h. With the 75% dilution, scattered mild redness (Draize score 1) was observed in 3 animal, respectively at 1 h. the skin was normal in any animal by 24 h.
According to the authors, based on these result, the undiluted test material (Ibuprofen gel 10% ) was selected for the topical induction and challenge in the main test.

MAIN STUDY
A. INDUCTION EXPOSURE

Intradermal:
A row of three injections (0.1 ml each) was made an each side of the mid-line. The injections were:
i) Freund's Complete Adjuvant plus arachis oil B.P. in the ratio 1:1;
ii) a 5% (w/v) dilution of test material in arachis oil;
iii) a 5% (w/v) dilution of test material in a 1:1 preparation of Freund's Complete Adjuvant plus arachis oil

Topical:
One week later, the undiluted test material (0.2 - 0.3 ml) was applied on filter paper which was held in place by a strip of surgical adhesive tape and covered with an overlapping length of aluminium foil. The patch and foil were further secured by a strip of elastic adhesive bandage. This occlusive dressing was kept in place for 48 hours.
Erythematous reactions were quantified 1 and 24 h following removal of the patches.

- No. of exposures: single intradermal injection, single topical application
- Exposure period: single intradermal injection, 48-h occluded patch
- Test groups: 5% intradermal, undiluted test material topical
- Control group: concurrent vehicle (intradermal), sham-exposed, i.e. filter paper containing no substance and concurrent coverings (topical)
- Site: neck (intradermal), shoulder (topical)
- Frequency of applications: single (intradermal and topical)
- Duration: 48 h (topical)
- Concentrations: 5% (w/v) intradermal, undiluted (topical)

B. CHALLENGE EXPOSURE
Two weeks after the topical inductions, an area on both flanks of each animal, was clipped free of hair. A quantity of 0.1 - 0.2 ml of the undiluted test material on a filter paper was applied to the shorn right flank. After 24 h, the dressing was carefully cut using blunt-tipped scissors, removed and discarded. The position of the treatment sites was identified by using a black indelible marker-pen. After a further 24 and 48 h, any erythematous reactions were quantified and the number of positive responses recorded.

- No. of exposures: single
- Day(s) of challenge: day 21 of the study
- Exposure period: 24 h
- Test groups: undiluted test material
- Site: flank
- Concentrations: undiluted
- Evaluation (hr after challenge): 24, 48 h after removal of the patches

OTHER:
Individual body weights of test and control animals were determined at day 0 and day 24.

POSITIVE CONTROL:
A Separate study (Safepharm project No. SF/6) with Formaldehyde, 40% aqueous solution was conducted in March 1987.
Twenty test and ten control animals were used for the study. Following sighting studies the following concentrations of Formaldehyde (40% aqueous solution) were used for the induction and challenge phases.
- intradermal induction: 0.1 % (w/v)
- topical induction (day 7): 50% /w/v)
- topical challenge (day 21): 10% (w/v)
For details, see attached files.

Challenge controls:

no data

Positive control substance(s):

yes

Remarks:

Formaldehyde (40% aqueous solution). Separate study (Safepharm project No. SF/6) conducted in March 1987.

Results and discussion

Positive control results:

In the test group (Formaldehyde, 40% aqueous solution), skin responses were seen in 19/20 animals after application of the test material and in 0/20 animals after application of the vehicle.
In the control group, skin responses were seen in 0/10 animals after application of the test material and in 0/10 animals after application of the vehicle.
The positive test material Formaldehyde (40% aqueous solution) therefore, produced a 95% (19/20) sensitisation rate and was classified as an extreme sensitiser to guinea pig skin.
For details, see attached file.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0

No. with + reactions:

2

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0. No with. + reactions: 2.0. Total no. in groups: 20.0.

Results 2

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

undiluted

No. with + reactions:

1

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: undiluted. No with. + reactions: 1.0. Total no. in groups: 20.0.

Results 3

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

undiluted

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: undiluted. No with. + reactions: 0.0. Total no. in groups: 20.0.

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0. No with. + reactions: 0.0. Total no. in groups: 20.0.

Any other information on results incl. tables

Induction:

Individual reactions were observed at the topical reaction sites of test and control animals.

Transient redness was elicited by ibuprofen gel.

Challenge:

There was no evidence of sensitization response. No skin reactions were observed in the 20 test or 20 control animals.

Body weights:

Body weight gains of guinea pigs in the test group, between day 0 and day 24, were comparable to those observed in the control group

animals over the same period.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

Classification: not sensitizing

Executive summary:

Abstract

Test material: IBUPROFEN GEL

1. A study was performed to assess the skin sensitisation potential of the test material in the albino guinea pig. The method used followed that described in the OECD Guidelines for Testing of Chemicals (1981) No. 406 "Skin Sensitisation" - Magnusson and Kligman Maximisation Test.

2. Twenty test and twenty control animals were used for the main study.. Following sighting studies, the following concentrations were used in the induction and challenge phases:

Intradermal Induction : 5'% (w/v)

Topical Induction: undiluted as supplied

Topical Challenge: undiluted as supplied

3. The test material did not produce a sensitisation reaction in any of the twenty test animals, and was classified as a non-sensitiser to guinea pig skin.