Isonicotinic acid

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2016-08-10 to 2016-09-05

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Isonicotinic acid

EC Number:

200-228-2

EC Name:

Isonicotinic acid

Cas Number:

55-22-1

Molecular formula:

C6H5NO2

IUPAC Name:

isonicotinic acid

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study reports): JNJ-40064973-AAA (Isonicotinezuur)
- Physical state: solid (powder)
- Appearance: white powder

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: M15HB3488
- Expiration date of the lot/batch: 2020-07-30 (retest date)
- Purity: 98.9%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Solubility and stability of the test substance in the solvent/vehicle: There was no information available regarding the solubility or stability in vehicle.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Test item preparation were prepared with 4 hours prior to each dosing.

In vivo test system

Test animals

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: female (nulliparous and non-pregnant) mice, CBA/J strain, inbred, SPF-Quality from Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: young adults: approx. 10 weeks old
- Weight at study initiation: Group 1: 20.9 - 21.7 g; Group 2: 20.0 - 22.9 g; Group 3: 20.1 - 23.6 g; Group 4: 23.8, 21.3 - 24.6 g
- Housing: group housed in labeled Makrolon cages (MIII type; height 18 cm) containing sterilised sawdust as bedding material (Lignocel S 8-15, JRS- J. Rettenmaier & Söhne GmbH + Co. KG, Rosenberg, Germany). Paper (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd.), Surrey, United Kingdom) and shelters (disposable paper corner home, MCORN 404, Datesand Ltd. USA) were supplied as cage-enrichment. On day 6, the animals were group housed in Makrolon MII type cages with a sheet of paper instead of sawdust and cage enrichment.
- Diet (e.g. ad libitum): ad libitum, pelleted rodent diet (SM R/M-Z from SSNIFF Spezialdiäten GmbH, Soest, Germany)
- Water (e.g. ad libitum): ad libitum, tap water
- Acclimation period: at least 5 days before the start of treatment, under laboratory conditions

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 to 24°C
- Humidity (%): 40 to 70%
- Air changes (per hr): at least 10 air changes/hour
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

propylene glycol

Concentration:

Pre-screen test: 25 and 50% (w/w)
Main study: 0, 2, 25 and 50% (w/w)

No. of animals per dose:

5 females per group; 4 groups

Details on study design:

PRE-SCREEN TESTS:
- Compound solubility: no data
- Irritation: No erythema observed in any of the animals examined
- Systemic toxicity: No signs of systemic toxicity were oserved in any of the animals examined. White test item remnants were present on the dorsal surface of the ears of all animals (between Days 1 and 3), which did not hamper scoring of the skin reactions.
- Ear thickness measurements: Variations in ear thickness during the observation period were less than 25% from Day 1 pre-dose values
- Erythema scores:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT - INDUCTION days 1, 2, 3
- Three groups of five animals were treated with one test item concentration per group. The highest test item concentration was selected from the pre-screen test. One group of five animals was treated with vehicle.
- The dorsal surface of both ears was topically treated (25 μL/ear) with the test item, at approximately the same time on each day for three consecutive days. The concentrations were stirred with a magnetic stirrer immediately prior to dosing.
- The control animals were treated in the same way as the experimental animals, except that the vehicle was administered instead of the test item.

EXCISION OF THE NODES - day 6
- Each animal was injected via the tail vein with 0.25 mL of sterile phosphate buffered saline (PBS) (Merck, Darmstadt, Germany) containing 20 μCi of ³H-methyl thymidine (PerkinElmer Life and Analytical Sciences, Boston, MA, US).
- After five hours, all animals were killed by intraperitoneal injection (0.2 mL/animal) of Euthasol® 20% (AST Farma BV, Oudewater, The Netherlands). The draining (auricular) lymph node of each ear was excised. The relative size of the nodes (as compared to normal) was estimated by visual examination and abnormalities of the nodes and surrounding area were recorded. The nodes were pooled for each animal in approximately 3 mL PBS.

TISSUE PROCESSING FOR RADIOACTIVITY - day 6
- Following excision of the nodes, a single cell suspension of lymph node cells (LNC) was prepared in PBS by gentle separation through stainless steel gauze (diameter 125 μm). LNC were washed twice with an excess of PBS by centrifugation at 200g for 10 minutes at 4ºC. To precipitate the DNA, the LNC were exposed to 5% trichloroacetic acid (TCA) (Merck, Darmstadt, Germany) and then stored in the refrigerator until the next day.

RADIOACTIVITY MEASUREMENTS - day 7
- Precipitates were recovered by centrifugation, resuspended in 1 mL TCA and transferred to 10 mL of Ultima Gold cocktail (PerkinElmer Life and Analytical Sciences, Boston, MA, US) as the scintillation fluid. Radioactivity measurements were performed using a Packard scintillation counter (2800TR). Counting time was to a statistical precision of ± 0.2% or a maximum of 5 minutes whichever came first. The scintillation counter was programmed to automatically subtract background and convert Counts Per Minute (CPM) to Disintegrations Per Minute (DPM).

- Criteria used to consider a positive response: A Stimulation Index (SI) is calculated for each group using the individual SI values. The individual SI is the ratio of the DPM/animal compared to DPM/vehicle control group. If the results indicate a SI ≥ 3, the test item may be regarded as a skin sensitizer.
The results were evaluated according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2011) (including all amendments) and the Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, including all amendments. Consideration was given to the EC3 value (the estimated test item concentration that will give a SI =3).
Classification of results:
UN-GHS 2007; EC-CLP 2008 EC Hazard statement
SI < 3 No sensitizer -
SI ≥ 3 Cat 1 Skin sensitizer H317: May cause an allergic skin reaction
EC3 value ≤ 2%: sub-category 1A
EC3 value ≥ 2%: sub-category 1B

TREATMENT PREPARATION AND ADMINISTRATION:
- The test item preparations (w/w) were prepared within 4 hours prior to each dosing.
- No adjustment was made for specific gravity of the vehicle.
- Homogeneity was assessed by visual inspection of the solutions. Correction of the purity/composition of the test item is not applicable, since the test method requires a logical concentration range rather than specific dose levels to be dosed.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

No statistics performed

Results and discussion

Positive control results:

At concentrations 5%, 10% and 25% SI values of the positive control item were 1.4, 1.5, and 4.3 respectively. An EC3 value of 18.0% was calculated using linear interpolation. The calculated EC3 value was in the accepable range of 4.8 and 19.5%.

Based on the results, it was concluded that the LLNA of the laboratory is an appropriate model for testing for contact hypersensitivity.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

0.9

Variability:

+/- 0.2

Test group / Remarks:

2% (w/w)

Results 2

Key result

Parameter:

SI

Value:

0.8

Variability:

+/- 0.2

Test group / Remarks:

25% (w/w)

Results 3

Key result

Parameter:

SI

Value:

1

Variability:

+/- 0.3

Test group / Remarks:

50% (w/w)

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA
DPM ± SEM:
0% w/w group: 928 ± 146
2% w/w group: 790 ± 88
25% w/w group: 778 ± 102
50% w/w group: 947 ± 222

DETAILS ON STIMULATION INDEX CALCULATION
The SI values calculated for the item concentrations 2, 25 and 50% were 0.9, 0.8 and 1.0, respectively.

EC3 CALCULATION
not calculated: no SI >=3 values when tested up to 50% w/w

CLINICAL OBSERVATIONS:
Skin reactions / irritation:
No erythema of the ears was observed in any of the animals examined.
White test item remnants were present on the dorsal surface of the ears of the animals treated at a concentration of 25% and 50% (between Days 1 and 3), which did not hamper scoring of the skin reactions.
Systemic toxicity:
No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study.
Macroscopy of the auricular lymph nodes and surrounding area:
All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size.
No macroscopic abnormalities of the surrounding area were noted for any of the animals.

BODY WEIGHTS
Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Since there was no indication that the test item elicited a SI>= 3 when tested up to 50%, it was not considered to be a skin sensitizer.

The six-month reliability check with Alpha-hexylcinnamaldehyde indicates that the Local Lymph Node Assay as performed at Charles Rive Den Bosch is an appropriate model for testing for contact hypersensitivity.

Based on these results, the test item was not regarded as a skin sensitizer according to the recommendations made in the test guidelines. The test item does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2015) (including all amendments) and the Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures (including all amendments).