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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02 August 2011 - 23 August 2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was performed in accordance with guidelines and GLP principles. As the study was done with a test substance analogue, the maximum Klimisch value is 2. The rationale to use the data in a read across approach is attached in section 13.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Report Date:
2011

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
(adopted 22 July 2010)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
(2011)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
dd 31 August 2011
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): AZ13449927 Na (NXL104)
- Substance type: Organic
- Physical state: Off white powder
- Analytical purity: No data
- Batch No.: AFCH005151
- Expiration date of the lot/batch: No data
- Storage condition of test material: Approximately 4°C in the dark over silica gel

In vivo test system

Test animals

Species:
mouse
Strain:
other: CBA/Ca (CBA/CaOlaHsd)
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Laboratories UK Ltd., Oxon, United Kingdom
- Age at study initiation: 15-23 g
- Weight at study initiation: 8-12 weeks
- Housing: Individually housed in suspended solid-floor polypropylene cages
- Diet: 2014C Teklad Global Rodent diet, ad libitum
- Water: Tap water ad libitum
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25 (target range)
- Humidity (%): 30-70 (target range)
- Air changes (per hr): Approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 02 August 2011 To: 23 August 2011

Study design: in vivo (LLNA)

Vehicle:
dimethyl sulphoxide
Concentration:
5%, 10%, 25% w/w.
No. of animals per dose:
4 (main study), 1 (dose finding study)
Details on study design:
RANGE FINDING TEST:
- Compound solubility: The vehicle was chosen as it produced the highest concentration that was suitable for dosing (at 25%).
- Irritation: The mouse was treated by daily application of 25 μl of the test item at a concentration of 25% w/w in dimethyl sulphoxide, to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). No signs of systemic toxicity, visual local skin irritation or irritation indicated by an equal to or greater than 25% increase in mean ear thickness were noted.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay
- Criteria used to consider a positive response: The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (disintegrations per minute/node) and as the ratio of 3HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index). The test item was regarded as a sensitiser if at least one concentration of the test item resulted in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test item failing to produce a threefold or greater increase in 3HTdR incorporation would be classified as a "non-sensitiser".

TEST SUBSTANCE PREPARATION
The test item was formulated within two hours of being applied to the test system. It is assumed that the formulation was stable for this duration.

ANIMAL ASSIGNMENT: random
Three groups of four animals were treated with one test substance concentration per group. One group of four animals was treated with vehicle.

Induction (the mice were treated by daily application of 25 µl of the appropriate concentration of the test item to the dorsal surface of each ear for 3 consecutive days); 3HTdR injection - Day 6; Excision of nodes - Day 6; Tissue processing for radioacitivity - Day 6; Radioactivity measurements - Day 7; Performed according to test guidelines.

Observations:
Body weights: On day 1 (pre-dose) and day 6 (prior to necropsy).
Clinical signs: Twice daily on days 1, 2 and 3 and on a daily basis on days 4, 5 and 6.

Necropsy: No data
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:
An LLNA was performed 09 June 2010 to 15 June 2010 with α-Hexylcinnamaldehyde (5 animals treated with 15% v/v α-Hexylcinnamaldehyde in DMSO (50 µl (25 µl per ear)). Stimulation index was 3.25 (mean value).

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Value:
>= 0.69 - <= 0.92
Variability:
0.75, 0.92 and 0.69 for animals treated with 5%, 10% and 25% respectively.
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: 16492.82, 12357.88, 15184.61 and 11318.64 for animals treated with 0%, 5%, 10% and 25% respectively.

Any other information on results incl. tables

There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test. Bodyweight changes of the test animals between day 1 and day 6 were comparable to those observed in the corresponding control group animals over the same period.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
In an LLNA skin sensitisation study, performed according to OECD/EC test guidelines, NXL 104 was found not to be a skin sensitiser, as the SI was < 3 when tested up to 25% w/w.
Executive summary:

An LLNA skin sensitisation study was performed according to OECD/EC test guidelines and GLP principles. Based on the results of a pre-screen test, the test concentrations were selected at 5%, 10% and 25% w/w. In the preliminary test, no skin irritation was observed at 25% w/w. No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. Mean DPM/animal values for the experimental groups treated with test item concentrations 5, 10 and 25% were 12358, 15185 and 11319 DPM, respectively. The mean DPM/animal value for the vehicle control group was 16493 DPM. The SI values calculated for the test item concentrations 5, 10 and 25% were 0.75, 0.92 and 0.69, respectively. As the SI was < 3 when tested up to 25% w/w, NXL104 is considered not to be a skin sensitiser.