4-aminobutyric acid

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented study according to international accepted guidelines and GLP compliant.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

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:

4-aminobutyric acid

EC Number:

200-258-6

EC Name:

4-aminobutyric acid

Cas Number:

56-12-2

Molecular formula:

C4H9NO2

IUPAC Name:

4-aminobutanoic acid

Test material form:

solid: crystalline

Details on test material:

Test item: 4-aminobutyric acid
CAS No. 56-12-2
Batch No. 0019D35 (10600120141102)
Physical state: solid substance, crystalline powder
Storage at: 15-30 °C

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

Species and strain: CBA/Ca Ola Hsd mice
Source: TOXI-COOP ZRT.
Hygienic level at arrival: SPF
Hygienic level during the test: Good conventional
Number of animals: 8 (2 animals/group)
Sex: Female, nulliparous, non-pregnant
Age of animals: Young adult mice; 12 weeks old (at start of the preliminary test)
Body weight range at starting: 18.7-23.6 g
Acclimatization time: 7 days
Animal health: Only healthy animals were used

Housing during acclimatization period: Grouped caging in small groups
Housing during the test: Grouped caging (4 animals/cage)
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 22 ± 3 °C
Relative humidity: 30 – 70 %

Study design: in vivo (LLNA)

Vehicle:

other: 1 % (w/v) Pluronic®PE 9200 in water

Concentration:

The test item was administered at four different concentrations (25; 10; 5; 2,5) according to the results of the dose range finding test.

No. of animals per dose:

4 animals

Details on study design:

Selection of test item concentrations was based on the results of a formulation evaluation and also results of preliminary irritation/toxicity test to find an appropriate solvent and the maximum applicable concentration according to the relevant guidelines. Based on the preliminary test results the test item was tested in the LLNA at 25 %, 10 %, 5 % and 2.5 % (w/v) concentrations as formulations in aqueous 1% Pluronic®PE 9200 (aqueous 1 % Pluronic).
Appropriate positive control (α-Hexylcinnamaldehyde, HCA), furthermore two negative control groups dosed with the vehicles of the test and positive control groups, respectively, were employed.
The positive control item (25 % (w/v) HCA in Acetone: Olive oil 4:1 (v/v) mixture, AOO) induced the appropriate stimulation over the control, thus confirming the validity of the assay.

Positive control substance(s):

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

Results and discussion

Positive control results:

The positive control group animals were treated with 25 % (w/v) HCA solution (dissolved in AOO) concurrent to the test item groups. No mortality, cutaneous reactions or signs of toxicity were observed in the positive control group.
Significant lymphoproliferative response (SI ≥ 3) was noted for HCA (SI = 5.0). The results of the positive control item demonstrated appropriate performance of the test in accordance with the relevant guidelines and confirmed validity of the assay.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

The stimulation index (SI = the DPN of a treated (positive control or test item) group divided by the DPN of the respective negative control group) for each treatment group was also calculated. A stimulation index of 3 or greater is an indication of a positive result. When monotonic dose-response is seen, attempt is made to calculate EC3 (dose calculated to induce a stimulation index of 3) with the help of linear regression on dose-response relationship. All calculations were made by Microsoft Excel Software.

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: see Remark

Remarks:

DPM (disintegration per minute) was measured for each treatment group. The measured DPM values were corrected with the background DPM value. The average of the two measured DPM values of 5 % (w/v) TCA solutions was used as the background DPM value. The results were expressed as DPN (DPM divided by the number of pooled lymph nodes).

Any other information on results incl. tables

Test GroupName	Measured DPM/group	Group* DPM	DPN (DPM/Node)	Stimulation IndexValues
Vehiclecontrol for the positive control: AOO	23412	23388.5	2923.6	1.0
Positivecontrol: 25 % HCAinAOO	117447	117423.5	14677.9	5.0
4 -aminobutyric acid 25% in aqueous 1% Pluronic	5057	5033.5	629.2	1.8
4 -aminobutyric acid 10% in aqueous 1% Pluroni	6888	6864.5	858.1	2.4
4 -aminobutyric acid 5% in aqueous 1% Pluroni	7588	7564.5	945.6	2.7
4 -aminobutyric acid 2.5% in aqueous 1% Pluroni	4858	4834.5	604.3	1.7
Vehiclecontrol for thetestitem: aqueous 1 % Pluronic	2855	2831.5	353.9	1.0

*Group DPM = measured DPMgroup- average DPMbackground

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

Migrated information

Conclusions:

In conclusion, under the conditions of the present Local Lymph Node Assay, 4-AMINOBUTYRIC ACID (CAS No. 56-12-2) tested at the maximum attainable concentration of 25% (based on solubility) and at concentrations of 10 %, 5 % and 2.5 % (w/v) as formulations in an appropriate vehicle (aqueous 1 %Pluronic) was shown to have no skin sensitization potential.