3-bromo-5-fluoro-1-[(4-methylphenyl)sulfonyl]-1H-pyrrolo[2,3-b]pyridine

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-09-19 to 2016-09-20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Well documented GLP-study according to OECD Guideline 437.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

3-bromo-5-fluoro-1-(4-methylbenzenesulfonyl)-1H-pyrrolo[2,3-b]pyridine

Cas Number:

1417421-99-8

Molecular formula:

C14H10BrFN2O2S

IUPAC Name:

3-bromo-5-fluoro-1-(4-methylbenzenesulfonyl)-1H-pyrrolo[2,3-b]pyridine

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: I15ID3592
- Expiration date of the lot/batch: 2017-09-21 (expiry date)
- Purity test date: no data

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: since no workable suspension of the test item in physiological saline could be obtained, the test item was used as delivered by the sponsor and added pure on top of the corneas.

Test animals / tissue source

Species:

other: Freshly isolated bovine cornea

Strain:

other: not applicable

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Vitelco, -'s Hertogenbosch, The Netherlands
- Bovine eyes were used as soon as possible but within 4 hours after slaughter. Bovine eyes from young cattle were obtained from the slaughterhouse, where the eyes were excised by a slaughterhouse employee as soon as possible after slaughter. Eyes were collected and transported in physiological saline in a suitable container under cooled conditions and tested the day of arrival in the laboratory.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 331 to 389 mg

NEGATIVE CONTROL
- Amount(s) applied (volume or weight with unit): 750 μl

POSITIVE CONTROL
- Amount(s) applied (volume or weight with unit): 750 μl
- Concentration (if solution): 20% (w/v) Imidazole

Duration of treatment / exposure:

Corneas were incubated for 240 ± 10 minutes at 32 ± 1°C

Duration of post- treatment incubation (in vitro):

After 240 ± 10 minutes of treatment, opacity was measured with an opacitometer. The permeability measurement of the corneas was performed after the incubation period of 90 minutes ± 5 minutes following the opacity measurement

Number of animals or in vitro replicates:

3 corneas were selected at random for each treatment group

Details on study design:

SELECTION AND PREPARATION OF CORNEAS
- The eyes were checked for unacceptable defects, such as opacity, scratches, pigmentation and neovascularization by removing them from the physiological saline and holding them in the light. Those exhibiting defects were discarded.
The isolated corneas were stored in a petri dish with cMEM (Eagle’s Minimum Essential Medium (Life Technologies, Bleiswijk, The Netherlands) containing 1% (v/v) L-glutamine (Life Technologies) and 1% (v/v) Foetal Bovine Serum (Life Technologies)). The isolated corneas were mounted in a corneal holder (one cornea per holder) of BASF (Ludwigshafen, Germany) with the endothelial side against the O-ring of the posterior half of the holder. The anterior half of the holder was positioned on top of the cornea and tightened with screws. The compartments of the corneal holder were filled with cMEM of 32 ± 1°C. The corneas were incubated for the minimum of 1 hour at 32 ± 1°C. After the incubation period, the medium was removed from both compartments and replaced with fresh cMEM.

TREATMENT METHOD
The medium from the anterior compartment was removed and 750 μl of the negative control and 20% (w/v) Imidazole solution (positive control) were introduced onto the epithelium of the cornea. The test item was weighed in a bottle and applied directly on the corneas in such a way that the cornea was completely covered (331 to 389 mg). The holder was slightly rotated, with the corneas maintained in a horizontal position, to ensure uniform distribution of the solutions over the entire cornea. Corneas were incubated in a horizontal position for 240 ± 10 minutes at 32 ± 1°C.

REMOVAL OF TEST SUBSTANCE
- Number of washing steps after exposure period: After the incubation the solutions and the test compound were removed and the epithelium was washed at least three times with MEM with phenol red (Eagle’s Minimum Essential Medium Life Technologies). Possible pH effects of the test item on
the corneas were recorded. Each cornea was inspected visually for dissimilar opacity patterns. The medium in the posterior compartment was removed and both compartments were refilled with fresh cMEM and the opacity determinations were performed.

METHODS FOR MEASURED ENDPOINTS
-CORNEAL OPACITY: Opacity determinations will be performed on each of the corneas using an opacitometer (BASF-OP3.0, BASF, Ludwigshafen, Germany). The opacity of each cornea will be read against a cMEM filled chamber, and the initial opacity reading thus determined will be recorded.
Corneas that had an initial opacity reading higher than 7 were not used.
The opacity of a cornea was measured by the diminution of light passing through the cornea. The light was measured as illuminance (l = luminous flux per area, unit: lux) by a light meter. The opacity value (measured with the device OP-KIT) was calculated according to:
opacity = ((I0/I)-0.9894)/0.0251
With I0 the empirically determined illuminance through a cornea holder but with windows and medium, and I the measured illuminance through a holder with cornea before/after test item treatment.
The change of opacity for each individual cornea (including the negative control) was calculated by subtracting the initial opacity reading from the final post-treatment reading. The corrected opacity for each positive control or test item treated cornea was calculated by subtracting the average change
in opacity of the negative control corneas from the change in opacity of each positive control or test item treated cornea. The mean opacity value of each treatment group was calculated by averaging the corrected opacity values of the treated corneas for each treatment group.

- Corneal permeability: passage of sodium fluorescein dye measured with the aid of microtiter plate reader (OD490)
The medium of both compartments (anterior compartment first) was removed. The posterior compartment was refilled with fresh cMEM. The anterior compartment was filled with 1 mL of 5 mg Nafluorescein/mL cMEM solution (Sigma-Aldrich Chemie GmbH, Germany). The holders were slightly rot
ated, with the corneas maintained in a horizontal position, to ensure uniform distribution of the sodium-fluorescein solution over the entire cornea. Corneas were incubated in a horizontal position for 90 ± 5 minutes at 32 ± 1°C. After the incubation period, the medium in the posterior compartment
of each holder was removed and placed into a sampling tube labelled according to holder number. 360 μL of the medium from e ach sampling tube was transferred to a 96-well plate. The optical density at 490 nm (OD490) of each sampling tube was measured in triplicate using a microplate reader (TECAN Infinite® M200 Pro Plate Reader). Any OD490 that was 1.500 or higher was diluted to bring the OD490 into the acceptable ra nge (linearity up to OD490 of 1.500 was verified before the start of the experiment). OD490 values of less than 1.500 were used in the permeability calculation.
The mean OD490 for each treatment was calculated using cMEM corrected OD490 values. If a dilution was performed, the OD490 of each reading was corrected for the mean negative control OD490 before the dilution factor was applied to the readings.

SCORING SYSTEM: In Vitro Irritancy Score (IVIS)
The mean opacity and mean permeability values (OD490) were used for each treatment group to calculate an in vitro score:
In vitro irritancy score (IVIS) = mean opacity value + (15 x mean OD490 value)
Additionally the opacity and permeability values were evaluated independently to determine whether the test item induced irritation through only one of the two endpoints.

The IVIS cut-off values for identifying the test items as inducing serious eye damage (UN GHS Category 1) and test items not requiring classification for eye irritation or serious eye damage (UN GHS No Category) are given hereafter:
In vitro score range UN GHS
≤ 3 No Category
> 3; ≤ 55 No prediction can be made
>55 Category 1

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

in vitro irritation score

Remarks:

mean of 3 eyes

Run / experiment:

1

Value:

-0.3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: range of IVIS score of test item: -1.2 to 1.4

Results 2

Irritation parameter:

cornea opacity score

Remarks:

mean of 3 eyes

Run / experiment:

1

Value:

-1.6

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: range of corneal opacity score of test item: -2.3 to -1.1

Results 3

Irritation parameter:

other: permeability score mean of 3 eyes

Run / experiment:

1

Value:

0.085

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: range of permeability value of test item 0.000 to 0.182

Other effects / acceptance of results:

mean in vitro irritancy score (range):
negative control: 2.4 (2.2 to 2.6); 7.6 was excluded from analysis (Study plan deviation)
positive control: 135.5 (119.1 to 147.2)
mean opacity scores (range):
negative control: 2.1 (2.0 to 2.3); 1.3 was excluded from analysis (Study plan deviation)
positive control: 92.8 (85.5 to 101.1)
mean permeability scores (range):
negative control: 0.021 (-0.002 to 0.044); 0.420 was excluded from analysis (Study plan deviation)
positive control: 2.852 (2.239 to 3.247)


The individual in vitro irritancy scores for the negative controls ranged from 2.2 to 2.6. One of the negative control eyes was excluded from the analysis since the IVIS >3 due to an permeability value which was above acceptance criteria, since the other 2 eyes completely met the criteria and test item results were not influenced by this result this does not affect the study outcome (Study Plan Deviation). The individual positive control in vitro irritancy scores ranged from 119 to 147. The corneas treated with the positive control were turbid after the 240 minutes of treatment

The corneas treated with the test item showed opacity values ranging from -2.3 to -1.1 and permeability values ranging from 0.000 to 0.182. The corneas were clear after the 240 minutes of treatment with the test item. No pH effect of the test item was observed on the rinsing medium. Hence, the in vitro irritancy scores ranged from -1.2 to 1.4 after 240 minutes of treatment with the test item.

Acceptance of results
The negative control responses for opacity and permeability were less than the upper limits of the laboratory historical range indicating that the negative control did not induce irritancy on the corneas. One of the negative control eyes was excluded from the analysis, since the permeability value was above acceptance criteria resulting in an IVIS score >3 (study plan deviation). The mean in vitro irritancy score of the positive control (20% (w/v) Imidazole) was 136 (119 to 147) and within the historical positive control data range. Furthermore the opacity and permeability values of the positive control were within two standard deviations of the current historical mean. It was therefore concluded that the test conditions were adequate and that the test system functioned properly.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Since the test item induced an IVIS ≤ 3, no classification is required for eye irritation or serious eye damage.