N-[(1R)-2-[(Methylsulfonyl)oxy]-1-phenylethyl]carbamic acid 1,1-dimethylethyl ester

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27 September - 25 October 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

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:

no

Test material

Test material information

Constituent 1

Reference substance name:

tert-butyl N-[(1R)-2-(methanesulfonyloxy)-1-phenylethyl]carbamate

EC Number:

855-580-5

Cas Number:

102089-75-8

Molecular formula:

C14H21NO5S

IUPAC Name:

tert-butyl N-[(1R)-2-(methanesulfonyloxy)-1-phenylethyl]carbamate

Test material form:

solid: particulate/powder

Test animals / tissue source

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

Bovine corneas, obtained as a byproduct from freshly slaughtered animals, were mounted in special holders and exposed to the test articles.

Bovine eyes were obtained from the abattoir of J.W. Treuth & Sons 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 the 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:

The solid test article was administered to the test system as 20% (w/v) (200 mg/mL) dilution in sterile, deionized water. The test article dilution was prepared by weighing the test article into a conical tube, adding sterile,deionized water, until a 20% (w/v) dilution was achieved, and then vortexing the dilution for approximately 1 minute prior to application. The positive control (20% (w/v) dilution of imidazole prepared in Complete Minimal Essential Medium (without phenol red) and the negative control (sterile, deionized water) were tested concurrently.

Duration of treatment / exposure:

Four corenas were incubated in a horizontal position at 32 ± 1 °C for approximately 4 hours. Three corneas were incubated in the presence of each control at 32 ± 1ºC.

Observation period (in vivo):

N/A

Duration of post- treatment incubation (in vitro):

After removal of the test or control article from the corneas, a final opacity was determined (the corneas did not receive a post-exposure incubation).

Number of animals or in vitro replicates:

Four corneas for the test article and three corenas 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 chamber was always filled first.

Test Item Preparation:
When appropriate, test articles were 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

Results 1

Irritation parameter:

in vitro irritation score

Value:

0.1

Positive controls validity:

valid

Remarks on result:

other: Mild Irritant based on Sina et al. Prediction Model

Results 2

Irritation parameter:

cornea opacity score

Value:

0

Positive controls validity:

valid

Other effects / acceptance of results:

The positive control in vitro irritancy score was 103. The positive control cornea opacity score 86.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the prediction model using Sina et al., the material was determined to be a mild irritant. However, based on the in vitro score of 0.1 and the prediction model found in OECD TG 437, the test material did not meet the GHS criteria for classification.