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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
Study period:
15 February 1996 to 18 March 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: A non GLP study performed to sound scientific principles with a sufficient level of detail to assess the quality of the submitted data.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1996
Report date:
1996

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
GLP compliance:
not specified
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Study was conducted for worker safety purposes prior to adoption of the OECD 429 Guideline for the Local Lymph Node Assay.

Test material

Constituent 1
Reference substance name:
Dl-Proline, 5-oxo-, compd. with N2-coco acyl-l-arginine Et ester
EC Number:
305-928-2
EC Name:
Dl-Proline, 5-oxo-, compd. with N2-coco acyl-l-arginine Et ester
Cas Number:
95370-65-3
IUPAC Name:
DL-Proline, 5-oxo-, compd. with N2-coco acyl-L-arginine Et ester
Test material form:
solid
Specific details on test material used for the study:
TREATMENT OF TEST MATERIAL PRIOR TO TESTING
The test material was prepared immediately before use.
- Preliminary study: The test material was weighed, added with distilled water (Otsuka, Lot No. K5L88), sonicated for 20 minutes, warmed for 1 minute at 30 °C, then made into 1.0 (w/w)% solution.
- Intradermal induction: The test material was weighed, added with distilled water (Otsuka, Lot No. 4B83), sonicated for 20 minutes, warmed for 1 minute at 30 °C, then made into 1.0 and 2.0 (w/w) % solutions. In addition, this 2.0 (w/w) % solution was pipetted and mixed with FCA (Difco Laboratories, Lot No. 64542LA) to prepare an emulsion (1:1).
- Epidermal induction: The test material 1.0 (w/w)% solution was made in the same way as intradermal induction.
- Challenge: The test material 1.0 (w/w)% solution was made in the same way as intradermal induction and epidermal induction.
- Preparation of emulsion (1:1) of Freund’s complete adjuvant and physiological saline: Freund’s complete adjuvant (FCA: Difco Laboratories, Lot No. 64542LA) was pipetted and mixed with physiological saline (Otsuka, Lot No. 4F85N) to prepare an emulsion (1:1).

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 5 weeks
- Weight at study initiation: 295.3 - 350.0 g
- Housing: Five animals were accommodated in each stainless-steel cage.
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period: 7 days. During the quarantine/acclimation period, the animals were observed for clinical signs once every day.

ENVIRONMENTAL CONDITIONS
- Temperature: 23 ± 3 °C
- Humidity: 55 ± 15 %
- Air changes: 10-15 times per hour
- Photoperiod: 12 hours lighting

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
water
Concentration / amount:
1.0 %, 0.05 mL
Day(s)/duration:
Day 1(intradermal) and Day 8 (epidermal for 48 hours)
Adequacy of induction:
non-irritant substance, but skin pre-treated with 10% SDS
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
1 %
Day(s)/duration:
Day 22 for 24 hours
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
10 per test material group, 5 per control group
Details on study design:
PRELIMINARY STUDY
- Two animals without abnormalities were selected. Fur of both flanks (approximately 5 x 10 cm) was clipped and shaved. On the next day, two patches of 2 x 2 cm were saturated with 0.2 mL of test material and applied to the clipped/shaved flank skin and covered occlusively with a bandage tape. The patches were removed 24 hours after application.
- The patch application sites were observed immediately after removing the patch and then 24 hours later. The skin reactions were scored according to the following scale:
No visible change = 0
Discrete or patchy erythema = 1
Moderate and confluent erythema = 2
Intense erythema and swelling = 3
- The concentration for the challenge was set at 1.0 (w/w) % (the maximum non-irritating concentration)

MAIN STUDY
INDUCTION
- Intradermal induction (Day 1): One day before intradermal induction, an area approximately 4 x 6 cm of the scapular region was clipped with electric clippers and shaved with an electric shaver. On the next day, 0.05 mL of each substance was intradermally administered to Areas 1 to 3 within an area of 2 x 4 cm. The substances and administration sites were as follows:
Area 1: 1:1 (v/v) mixture emulsion of physiological saline and FCA
Area 2: 1.0 % test material solution
Area 3: 1:1 (v/v) mixture emulsion of 2.0 % test material solution and FCA
- Epidermal induction (Day 8): On Day 6 after the intradermal induction, the same area as on Day 1 was clipped and shaved, and Vaseline containing 10 % sodium lauryl sulphate was applied thoroughly. On the next day, a patch of 2 x 4 cm was saturated with 0.5 mL of 1.0 (w/w)% substance, applied to the induction area and covered occlusively with a plastic film tape (Plasupport, HOGY Medical Co., Ltd.). The patch was removed 48 hours after application.

CHALLENGE (DAY 22)
- 20 days after the intradermal induction, fur of the right flank (approximately 5 x 10 cm) of animals was clipped and shaved. On the next day, the patch of 2 x 2 cm was saturated with 0.2 mL of 1.0 (w/w) % test material and fixed in place with a bandage tape for 24 hours for occlusive application of the challenge.

OBSERVATIONS
- Clinical signs: Clinical signs of all animals were observed once daily from delivery of the animals to the termination of the animal test.
- Body weight measurement: All animals were weighed on Day 1 (intradermal induction), Day 8 (epidermal induction), Day 22 (challenge), Day 24 and Day 25 (observation period).
- Skin reactions: Observation of skin reactions was performed 24 and 48 hours after removing the applied patch for the challenge. The skin reactions were scored and recorded according to the following scale:
No visible change = 0
Discrete or patchy erythema = 1
Moderate and confluent erythema = 2
Intense erythema and swelling = 3
- For each application site, the skin reaction of individual animals was scored and the mean score of each test group at each observation period was calculated, and the positive reaction rate [(number of animals with skin reactions of score 1 or greater) / (number of animals used) x 100] was determined.
The test material was assigned to one of the following five grades of allergenic potency according to Magnusson and Kligman, ranging from weak to extreme:
Positive reaction rate (%): 0 – 8 = Grade I (Weak)
Positive reaction rate (%): 9 – 28 = Grade II (Mild)
Positive reaction rate (%): 29 – 64 = Grade III (Moderate)
Positive reaction rate (%): 65 – 80 = Grade IV (Strong)
Positive reaction rate (%): 81 – 100 = Grade V (Extreme)
Challenge controls:
No-induction control group.
Positive control substance(s):
not specified

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
1.0 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
1.0 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
other: control group
Dose level:
1.0 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
other: control group
Dose level:
1.0 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation

Any other information on results incl. tables

Clinical signs

- There were no mortalities, or abnormal clinical signs observed during the study period.

 

Body weights

- Seven animals in the test material group and 2 animals in the control group at the challenge observation period (Day 24), and 1 animal in the test material sensitisation group at the challenge observation period (Day 25) showed a loss of body weight. This was judged to be unrelated to the test material, although the cause of the decrease was unclear.

 

Skin reactions

- No skin reactions were observed at the 1.0 (w/w) % test material application site in the test group and the control group. Thus, the mean score was 0 and the positive reaction rate was 0 %.

Applicant's summary and conclusion

Interpretation of results:
other: Not classified according to EU criteria.
Conclusions:
Under the conditions of the study, the test material was determined to be non-sensitising to skin.
Executive summary:

The potential of the test material to cause skin sensitisation was assessed in guinea pigs in accordance with the maximisation test.

The skin sensitization study was conducted in female Hartley strain guinea pigs with the Maximization Test Method. The maximum non-irritating concentration of the test material was determined to be 1.0 % (w/w) in the preliminary study.

In the induction phase of the study the animals were treated intradermally on Day 1 on a clipped area on the scapular region of the animals. On Day 8 they were treated with an epidermal induction under an occlusive patch for 48 hours. The challenge was performed on Day 22 with an occlusive application of the test material for 24 hours. Clinical signs, body weight measurements and skin reactions were recorded.

None of the test group or control group showed skin reactions after the challenge treatment with the test material at 1.0 % in distilled water.

Under the conditions of the study, there was no dermal sensitisation potential in guinea pigs for the test material, therefore, the test material was determined to be non-sensitising.