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Toxicological information

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:
2012-09-17 - 2013-02-05
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The GPMT was regarded as reliable method. Since no LLNA study was available, it was justified not to perform a new study with experimental animals .

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
Name N-((3(5)-Methyl-1H-pyrazol-1-yl)¬methyl)¬acetamid (MPA)
Batch No. P70/05/S-6
Content 96.2%

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
Species / Strain Guinea pig / Dunkin-Hartley

Breeder Charles River Laboratories,
Research Models and Services,
Germany GmbH
Stolzenseeweg 32 – 36
88353 Kißlegg
Germany

Selection of species According to international recommendations

Number of animals 15

Sex Male

Age
(at start of administration) 37 days

Body weight
(at start of administration) 330 - 384 g
(excluding positive control group)
Positive control group: 316 – 370 g

Identification of animals By cage label and coloured marks

Adaptation period At least 5 days

The animals were kept in pairs in MAKROLON cages (MZK 80/25) at a room tempera-ture of 22°C ± 3°C (maximum range) and a relative humidity of 55% ± 15% (maximum range).

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
other: Aqua ad iniectabilia (stages 1, 2 and 3)
Concentration / amount:
Induction: intracutaneous: 10% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia
Induction: topical: 75% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia
Challenge: topical: 75% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
other: Aqua ad iniectabilia (stages 1, 2 and 3)
Concentration / amount:
Induction: intracutaneous: 10% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia
Induction: topical: 75% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia
Challenge: topical: 75% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia
No. of animals per dose:
Tehicle control: 5 animals
Treatment group: 10
Details on study design:
Stage 1 (induction)
Day 0
Three pairs of intradermal injections of 0.1 mL were given in the shoulder region which was cleared of hair so that one of each pair lay on each side of midline.
(1) Freund's complete adjuvant (FCA)
(diluted 1 : 1 with 0.9% NaCl )

(2) the test item (N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid) (10%)

(3) the test item in a 1+1 mixture (v/v) FCA/physiological saline

In injection 3, the final concentration of the test item was equal to that in injection 2.
Injections (1) and (2) were given close to each other and nearest the head, while (3) was given towards the caudal part of the test area.

Day 6
As a 75% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia was non-irritating to the non-depilated skin of the test animals in the preliminary experiment, the fur was shaved from the application area and the exposed skin was coated with 0.5 mL sodium laurylsulfate 10% in vaseline in order to induce a local irritation.

Stage 2 (induction)
Day 7
7 days after the intracutaneous injection, the shoulder region of the same animals was shaved again and treated topically with test item (75% concentration) using the patch-test technique (exposure time: 48 hours). The patch was removed after 48 hours. No cleaning of the skin was necessary.

Stage 3 (challenge)
Day 21
Two weeks after the topical application (corresponds to a monitoring period of 21 days) the flanks of the same animals were shaved and depilated for a further topical application with test item (75% concentration) using the patch-test technique. The filter paper containing the test item was applied to the left flank, the filter paper with the vehicle to the right flank of the animal (exposure time: 24 hours). 21 hours after the filter paper had been removed the treated skin was cleaned and fur removed, if necessary.
Positive control substance(s):
yes
Remarks:
α-hexyl cinnamic aldehyde

Results and discussion

Positive control results:
Animals of the same strain treated with -hexyl cinnamic aldehyde in sesame oil exhibited a sensitising reaction in all animals in form of a moderate and confluent erythema (grade 2).

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
10% (intracutaneous), 75% (topical)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no effects
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 10% (intracutaneous), 75% (topical). No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no effects.
Reading:
2nd reading
Hours after challenge:
72
Group:
test group
Dose level:
10% (intracutaneous), 75% (topical)
No. with + reactions:
0
Total no. in group:
0
Clinical observations:
no effects
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 10% (intracutaneous), 75% (topical). No with. + reactions: 0.0. Total no. in groups: 0.0. Clinical observations: no effects.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
no effects
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: no effects.
Reading:
2nd reading
Hours after challenge:
72
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
no effects
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 0. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: no effects.
Reading:
1st reading
Hours after challenge:
48
Group:
positive control
Dose level:
10 % (intracutaneous), undiluted (topical), 0.01 % challenge
No. with + reactions:
20
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 10 % (intracutaneous), undiluted (topical), 0.01 % challenge. No with. + reactions: 20.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
positive control
Dose level:
10 % (intracutaneous), undiluted (topical), 0.01 % challenge
No. with + reactions:
20
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: positive control. Dose level: 10 % (intracutaneous), undiluted (topical), 0.01 % challenge. No with. + reactions: 20.0. Total no. in groups: 20.0.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Under the test conditions, N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid revealed no sensitising properties in guinea pigs in a test model according to MAGNUSSON and KLIGMAN and OECD guideline 406.
Executive summary:

The purpose of this study was to determine the potential of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid to produce skin sensitisation reactions in guinea pigs in a test model according to the MAGNUSSON and KLIGMAN method and OECD guideline 406.

A 10% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia chosen for the 1st (intracutaneous) induction stage did not reveal any skin reactions.

2 mL of a 75% suspension N-((3(5)-Methyl-1H-pyrazol-1-yl)­methyl)­acetamid/animal chosen for the 2nd (topical) induction stage were not irritating to the shaved skin in the preliminary experiment.

Hence, in the main study the skin was coated with sodium laurylsulfate on the day before stage 2 induction in order to induce a local irritation. This treatment resulted in a discrete or patchy erythema in all test group animals 48 and 72 hours after start of exposure.

A 75% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia was the maximum concentration that could be prepared in order to produce a homogeneous test item-vehicle preparation. No higher suitable concentration could be prepared.

The challenge with 2 mL of a 75% suspension of N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid in aqua ad iniectabilia/animal revealed no skin irritation in any animal and, thus, the test item had no sensitising properties.

The vehicle control revealed no skin reactions.

Animals of the same strain treated witha-hexyl cinnamic aldehyde in sesame oil exhibited a sensitising reaction in all animals in form of a moderate and confluent erythema (grade 2).

The body weight gain of the animals treated with N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid was within the range of the vehicle control during the experiment.

Behaviour remained unchanged during the course of the study.

Therefore N-((3(5)-Methyl-1H-pyrazol-1-yl)methyl)acetamid had no skin sensitizising properties.