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Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well documented study, comparable to guideline and acceptable for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1982
Report date:
1982

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
GLP compliance:
no
Type of study:
guinea pig maximisation test

Test material

Constituent 1
Chemical structure
Reference substance name:
Azelaic acid
EC Number:
204-669-1
EC Name:
Azelaic acid
Cas Number:
123-99-9
Molecular formula:
C9H16O4
IUPAC Name:
azelaic acid
Details on test material:
- Name of test material (as cited in study report): ZK 62.498 (azelaic acid)
- Physical state: solid
- Lot/batch No.: ZK 62.498
- Stability under test conditions: Suspensions of the test material between 1 and 125 mg/ml are stable for 72 hrs.
- Storage condition of test material: room temperature

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: Pirbright White
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Hagemann
- Weight at study initiation: 364 - 475 g
- Housing: housed under standardized conventional conditions
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 19 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C):22.5 -23 °C
- Humidity (%): 43-70 %
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
other: 0,9 g NaCl + 0,085 g Myrj 53 ad 100,0 ml bidist. water
Concentration / amount:
Intradermal induction: 0,5 % W/V
Epicutaneous induction: 25 % W/V
Epicutaneous challenge: 15 % W/V
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
other: 0,9 g NaCl + 0,085 g Myrj 53 ad 100,0 ml bidist. water
Concentration / amount:
Intradermal induction: 0,5 % W/V
Epicutaneous induction: 25 % W/V
Epicutaneous challenge: 15 % W/V
No. of animals per dose:
20
Details on study design:
Housing conditions and allocation of test animals
40 Pirbright White guinea pigs (20M, 20F), breeder Hagemann, identification by ear marks and ear cuts, acclimatization period 19 days,
were allocated to two groups of 10M and 10F each by lot. Generally two animals were kept in one cage. They were housed under standardized
conventional conditions (room temperature 22,5-23°c, rel. humidity 43-70 %, 12-hours day-night-rhythm). Altromin MS and tap water were
available ad libitum.

One group underwent a sensitizing treatment procedure (induction) with a subsequent epidermal administration as challenge while the other one
was reserved for a one-time epidermal administration as a local tolerance test to be carried out in parallel to the challenge.

Induction procedure
Intradermal injections
In the neck region (right and left side of the spine) an overall area of 4 x 6 cm was shaved in each animal (10M + 10F). A total of 6 intradermal
injections, 3 on each side, of the following formulations were made.
The injections were set within an area of 2 x 4 cm. The above mentioned concentration of ZK 62.498 was previously proved not to produce necrosis and ulcerations after intradermal application in the same region.

Epidermal application
In order to favour the sensitizing effect of ZK 62.498, the same area of skin (4 x 6 cm) in which intradermal injections were performed
was reshaved on day 8 of the test to be followed by treatment with 1 ml sodium lauryl sulphate (10 W/V %) in paraffin oil.
24 hours later, on day 9, approximately 0.2 ml of a 25 W/V % aqueous suspension of ZK 62.498 was spread over a 2 x 4 cm filter paper
(Whatmann, No 3MM). This was then applied on the above mentioned area pretreated with sodium lauryl sulphate. The patch was bandaged occlusively for 48 hours. ZK 62.498 25 W/V % was previously proved to be non-irritating on the skin after epidermal administration under occlusive
conditions.

Challenge procedure
On day 22 (two weeks after the epidermal administration) a skin area of 5 x 5 cm was shaved on the right flank of each animal.
Approximately 0.1 ml of ZK 62.498 (15 W/V %) in paraffin oil (ZK 62.498 25 W/V% in paraffin oil could not be formulated) which previously proved to be locally tolerated was spread over a 2 x 2 cm piece of filter paper. This patch was placed in the middle of the shaved area of skin and bandaged occlusively for 24 hours.
Reactions were recorded 24 and 48 hours after removal of the occlusive bandage.
Three hours prior to the first reading the test area was shaved with precaution.

Local tolerance test
A local tolerance test with the same formulation as used for the challenge and following exactly the challenging procedure was carried
out simultaneously to the challenge in the other 10M and 10F animals. This group served as control.

Reading and recording of local reactions
48 and 72 hours after the epidermal administration of ZK 62.498 (15 W/V %) suspended in paraffin oil in the right flank region in pretreated (test group) as well as in untreated (control group) animals, i.e. 24 and 48 hours after the occlusive bandage was removed, the local reaction was recorded according to the following scheme:
0 - neither reddening nor swelling
1 - slight reddening
2 - mild reddening
3 - severe reddening
4 - slight swelling
5 - mild swelling
6 - severe swelling
additional findings

Evaluation of findings
The types and the number of reactions in both groups were compared visually. Any clear cut increase in the number and severity of reactions
in pretreated animals was considered indicative of a sensitizing potential of the test compound in guinea pigs .
Challenge controls:
20 control animals were used
Positive control substance(s):
not specified

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
48
Group:
test chemical
Dose level:
15 %
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 15 %. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
test chemical
Dose level:
15 %
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 15 %. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
15 %
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 15 %. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
negative control
Dose level:
15 %
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 15 %. No with. + reactions: 0.0. Total no. in groups: 20.0.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU

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