6-METHOXYPYRIDINE-3-CARBALDEHYDE

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 August - 7 November, 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

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

Test material

Test material information

Constituent 1

Reference substance name:

6-methoxypyridine-3-carbaldehyde

Cas Number:

65873-72-5

Molecular formula:

C7H7NO2

IUPAC Name:

6-methoxypyridine-3-carbaldehyde

Test material form:

solid: particulate/powder

Details on test material:

Batch (Lot) Number: 2019-03-29
Physical Description: Cream powder
Storage Conditions: Kept in a controlled room temperature area, protected from light

Test animals / tissue source

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

Test System: The test system was isolated bovine cornea obtained as a byproduct from freshly slaughtered animals. The corneas were mounted in special holders and exposed to the test article.

Source/transport: Bovine eyes were obtained from the abattoir of J.W. Teruth & Sonsn INc., Baltimore, MD. The eyes were excised as soon after slaughter as possible and were held in HBSS on ice. Once the eyes were obtained, they were transported to IIVS. Immediately upon reciept of hte eyes to the lab, preparation of the corneas was initiated.

Test system

Vehicle:

other: deionized water

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

20% (w/v)/ (200mg/mL)

Duration of treatment / exposure:

Three corneas were incubated in the presence of the test article at 32 ± 1 °C for 4 hours. Three corneas were incubated in the presence of each control at 32 ± 1 °C for 4 hours. After removal of the test or control article from the corneas, a final opacity was determined.

Observation period (in vivo):

N/A

Duration of post- treatment incubation (in vitro):

N/A

Number of animals or in vitro replicates:

Three corneas for the test article and three corneas for each control

Details on study design:

Preparation of Corneas:
All the eyes were carefully examined for defects and those exhibiting defects were discarded. The tissue surrounding the eyeball was carefully pulled away and the cornea was excised leaving a 2 to 3 mm rim of sclera. The isolated corneas were stored in a petri dish containing HBSS prior to mounting. Corneas were then mounted in corneal holders with the endothelial side against the O-ring of the posterior chamber. The anterior chamber was positioned on top of the cornea and tightened with screws. The chambers of the corneal holder were filled with complete MEM. THe posterior champer was always filled first.

Test Item Preparation:
When appropriate, test articles wer diluted or suspended in either sterile deionized water or other Sponsor-directed solvent.

Treatment of Corneas and Opacity Measurements:
Solid materials were tested as a 20% dilution w/v in sterile deionized water. 750 uL of the test substance was introduced into the anterior chamber. Although it was understood that a 750 uL dose could not be achieved, the corneas were to be completely covered with the test material. The holder was slightly rotated to ensure uniform distribution of the test substance over the cornea. The corneas were incubated in a horizontal position at 32 +/- 1 degree C for approximately 4 hours. The test substance was then removed and the epithelium washed at least 3 times with Complete MEM. Once the media was free of the test material, the corneas were given a final rinse with Complete MEM. If the test material could not be removed from the cornea a note was recorded in the raw data report. The anterior and posterior chambers were then refilled with fresh Complete MEM and an opacity measurement performed immediately.

Opacity Measurement:
The opacitometer determined the difference in light transmission between each treated or control cornea and an air-filled chamber, and a numerical opacity value was recorded.

Permeability Determinations and application of sodium fluorescein:
After the opacity measurement was performed, the medium was reomved from the anterior chamber only and replaced with 1 mL of a 5 mg/mL sodium fluorescein solution. After the addition of the fluorescein solution to the anterior chamber, the corneas were incubated in a horizontal position for approximately 90 minutes at 32 +/- 1 degree C. The medium from the posterior chamber was removed at the completion of the incubation period, and 360 uL was transferred to the appropriate wells of a labeled 96-well plate. 360 uL of fresh Complete MEM were added to the wells designated as blanks. The optical density at 490 nm was determined using a spectrophotometer. Samples reading 1,500 and above were diluted to bring the reading within the linear range of the platereader and the plate was read again.

Results and discussion

In vitro

Results

Irritation parameter:

in vitro irritation score

Value:

26.6

Positive controls validity:

valid

Other effects / acceptance of results:

The positive control in vitro irritancy score was 84.3.

Applicant's summary and conclusion

Interpretation of results:

other: Self-classified as category 2

Conclusions:

In conclusion, based on the in vitro score of 26.6, and the prediction model found in OECD test guideline 437, no prediction was made for this test article concerning ocular irritation. The study sponsor classified this test article as a moderate irritant.