2(1H)-Pyridinone, 4-amino-5-methyl-

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

April 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-amino-5-methyl-1,2-dihydropyridin-2-one

EC Number:

682-818-3

Cas Number:

95306-64-2

Molecular formula:

C6 H8 N2 O

IUPAC Name:

4-amino-5-methyl-1,2-dihydropyridin-2-one

Test material form:

solid

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Solubility and stability of the test substance in the solvent/vehicle: Analytical determination of stability and homogeneity of the test item in the vehicle was not performed specifically for this study.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test item was suspended with a glass rod, a whirl mixer, and shaking shmily prior to application in isotonic saline solution to achieve a concentration of 20 % (w/v). During application the suspension was stirred on a magnet stirrer.

FORM AS APPLIED IN THE TEST (if different from that of starting material): The preparation was visually described as suspension.

Test animals / tissue source

Details on test animals or tissues and environmental conditions:

Bovine eyes of slaughtered cattle were extracted and transferred in containers with Hank’s balanced salt solution (HBSS) with penicillin/streptomycin solution. For transportation the containers were ice cooled.
Eyes with defects were sorted out and disposed of, eyes without any defects were transferred into fresh HBSS supplemented with penicillin/streptomycin solution and 1 % FBS and stored overnight at 2-8 °C. On the next day (day of testing) the containers with the eyes were placed in an incubator at 32 ° C (± 1 ° C) for about 2 hours before preparation of the corneas.

Test system

Vehicle:

physiological saline

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 750 μL per cornea and chamber
- Concentration (if solution): 20 % (w/v)

VEHICLE
- Amount(s) applied (volume or weight with unit): 750 μL per cornea and chamber
- Concentration (if solution): 0.9% NaCl (w/v)

Duration of treatment / exposure:

4 hours

Duration of post- treatment incubation (in vitro):

no further incubation required

Number of animals or in vitro replicates:

3 cornea

Details on study design:

Immediately before application, the medium was aspirated from the anterior chamber. 750 μL of the test material formulations were applied to the corneas, each through the holes of the anterior chamber. The holes of both chambers were sealed with adhesive tape and the holders were kept with the front side up, so that the formulations covered the cornea sufficiently (closed chamber method). The holders were transferred into the incubator at 32 °C (± 1 °C) for the exposure time of 4 hours. After the exposure, the formulations were aspirated from the anterior chamber and the corneas were rinsed at least 3 times with phenol red containing MEM to show effectiveness of test substance removal. During the final rinse cycle the corneas were rinsed again with pure MEM medium in order to remove residues of the dye. The anterior chamber was then filled again with MEM medium to avoid drying out of the cornea. Before measuring opacity, fresh MEM medium was filled in the chambers.

Positive control: 20 % Imidazole in physiologic saline (w/v; 750 µL)

TREATMENT METHOD: closed chamber

POST-INCUBATION PERIOD: no

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity: The opacity of a cornea was measured by the diminution of light passing through the cornea. The measurements of opacity were carried out using an opacitometer BASF OP3.0 (with integrated light meter testo 545 and Comfort 3.4 SP6 software from Testo AG, Lenzkirch). Before each measurement the opacitometer was adjusted to about 1000 LUX and a filter calibration measurement was carried out by using 3 different filters.
- Corneal permeability:The medium in anterior chamber of each holder was replaced by 1ml of fluorescein sodium solution (concentration 5 mg/mL). Afterwards the holders were incubated at 32 °C (± 1 °C) for about 90 minutes. After the incubation period, the medium of the posterior chamber was aspirated by a syringe and filled into a 10 mL tube. Three wells of a 96 well plate were filled with 300 μL of each tube (triplicate determination). In addition, a standard series of 5 mg/mL sodium fluoresceinsolution was prepared and also filled into the 96-well plate, in triplicates.
The permeability was determined by measuring the amount of fluorescein sodium which diffused through all cell layers of the cornea. The measurement was carried out at a wavelength of 490 nm (OD490) by an ELISA - Reader (Bio-Tek EL 808, Software Gen5).

SCORING SYSTEM: In Vitro Irritancy Score (IVIS)

DECISION CRITERIA:decision criteria as indicated in the OECD TG 437

Results and discussion

In vitro

Results

Irritation parameter:

in vitro irritation score

Run / experiment:

mean

Value:

-0.3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

Table 1: Individual values of opacity, permeability and IVIS

Cornea No.	Opacity per cornea	Permeability per cornea	IVIS per cornea	IVIS per group
				mean		SD
Negative control                    1	-4	0.007	-3.9
0.9 % NaCl                           2	1.1	0.007	1.2	-1.7		2.6
3	-2.5	0.007	-2.4
Positive Control                     4	76.9	1.090	93.3
20 % Imidazole                      5	64.8	1.613	89.0	95.4		7.7
6	92.9	0.737	104.0
Test item                                10	1.1	-0.001	1.1
20%   4-Amino-5 -methylpyridon  11	1.8	0.000	1.8	-0.3		3.0
12	-3.8	0.000	-3.8

 

Applicant's summary and conclusion

Interpretation of results:

other: negative

Executive summary:

The test item (20 % (w/v) in isotonic saline) was tested in the BCOP test according to OECD TG 437. For determination of corneal damage opacity as well as tissue permeability was measured after a 4 hour exposure time. Based on these data, in comparison to the vehicle control, the mean In Vitro Irritancy Score (IVIS) value was calculated to be -0.3 which is below the IVIS cut-off threshold of 55 and thus identifying the test item as not inducing serious eye damage. The results of the positive (20 % imidazole solution) and negative (isotonic saline solution) controls confirmed the validity of the test system.