Strontium neodecanoate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-04-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying Ocular Corrosives and Severe Irritants)

Version / remarks:

adopted 2013-07-26

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Bovine Corneal Opacity and Permeability (BCOP) Assay, SOP of Microbiological Associates Ltd., UK, Procedure Details, April 1997

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2013-04-11

Test material

Test material information

Constituent 1

Reference substance name:

Strontium neodecanoate

Cas Number:

106705-37-7

Molecular formula:

C10H19O2.xSr

IUPAC Name:

Strontium neodecanoate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

- Name of test material: strontium neodecanoate
- Molecular formula: (C10H19O2)2Sr
- Molecular weight: 429.6 g/mole
- Physical state: solid, beige, powder
- Stability in solvent: reacts strong with oxidising substances
- Storage condition of test material: cool, dry place (at room temperature

Test animals / tissue source

Details on test animals or tissues and environmental conditions:

Not applicable - Since this is an in vitro study there is no information on test animals.

Test system

Vehicle:

physiological saline

Amount / concentration applied:

TEST MATERIAL
- Concentration: test item was tested as a 20% suspension (w/v) in saline. Due to insoluble clumps of the test item, therefore one clump of the test item in 0.75 mL of the prepared coarse suspension was distributed to each cornea. Thereby it was taken care of that the corneae were evenly covered with the test item.

Duration of treatment / exposure:

240 minutes

Observation period (in vivo):

not applicable

Number of animals or in vitro replicates:

not applicable

Details on study design:

COLLECTION OF BOVINE EYES
- isolated bovine eyes of at least 9 month old donor cattle were collected from the abattoir and were transported in Hank's buffered salt solution (HBSS) supplemented with streptomycin / penicillin at ambient temperature.

PREPARATION OF CORNEAE
- all eyes were carefully examined macroscopically for defects.
- the cornea was carefully removed from the eye.
- each cornea was mounted in a specially designed cornea holder according to the description given in OEDC guideline 437, that consists of anterior and posterior compartments, which interface with the epithelial and endothelial sides of the cornea, respectively. Both compartments of the holder were filled with incubation medium.
- for equilibration, the corneae in the holder were incubated in a vertical position for one hour at 32 ± 1 °C in a water-bath.
- at the end of the incubation period, the basal opacity was determined (t0) of all cornea.
- each corneae with a value of the basal opacity > 7 was discarded.

EXPOSURE OF THE CORNEAE TO THE TEST GROUPS
- the anterior compartment received the test item suspension or negative control (saline) or positive control (10% (w/v) benzalkonium chloride in 0.9% (w/v) NaCl (saline)) at a volume of 0.75 mL each on the surface of the corneae.
- the corneae were incubated in a horizontal position at 32 ± 1 °C in the water-bath (incubation time: 240 minutes).
- the test item, positive control and negatice control were tested in triplicate.
- the test item or control items were rinsed off with saline
- incubation medium was added into the anterior compartment and opacity was measured (t240)
- permeability of the corneae was determined.

PERMEABILITY MEASUREMENT
- after the final opacity measurement, the incubation medium was removed from the anterior compartment and replaced by 0.5% (w/v) sodium fluorescein solution in HBSS.
- corneae were incubated in a horizontal position for 90 ± 10 minutes in a water-bath at 32 ± 1 °C.
- incubation medium from the posterior compartment was removed, well mixed and the optical density at 490 nm was determined with a spectrophotometer. The absorbance values were determined using the software SoftMax Pro Enterprise, version 4.7.1.

EVALUATION OF RESULTS
- Opacity: the change of opacity value of each treated cornea or positive and negative control corneae is calculated by subtracting the initial basal opacity from the post treatment opacity reading (t240 – t0), for each individual cornea.
The average change in opacity of the negative control corneae is calculated and this value is subtracted from the change in opacity of each treated cornea or positive control to obtain a corrected opacity.
- Permeability: the corrected OD490 value of each cornea treated with positive control and test item is calculated by subtracting the average negative control cornea value from the original permeability value for each cornea.

IN VITRO IRRITATION SCORE CALCULATION
The following formula was used to determine the in vitro irritation score (IVIS) of the negative control:
In vitro Irritation Score = opacity value + (15 x OD490 value)
The following formula was used to determine the in vitro irritation score of the positive control and the test item:
In vitro Irritation Score = (opacity value – opacity value mean negative control) + (15 x corrected OD490 value)
The mean IVIS value of each treated group was calculated from the IVIS values.
Depending on the score obtained, the test item was classified into the following category according to OECD guideline 437 (table 1 in the field "Any other information on materials and methods incl. tables" below)

CRITERIA FOR DETERMINATION OF A VALID TEST
The test was acceptable if
- the positive control gives an IVIS that falls within two standard deviations of the current historical mean (updated every three months), and if
- the negative control responses result in opacity and permeability values that are less than the established upper limits for background opacity and permeability values for bovine corneae treated with the respective negative control.

Results and discussion

In vitro

Results

Irritation parameter:

in vitro irritation score

Run / experiment:

Time point: 240 min.

Value:

166.9

Other effects / acceptance of results:

Relative to the negative control, the test item strontium neodecanoate caused an increase of the corneal opacity and permeability. The calculated mean IVIS was 166.90 (threshold for serious eye damage: IVIS ≥ 55). According to OECD 437 the test item is classified as serious eye damaging.

Any other information on results incl. tables

Table 1: Results after 240 minutes incubation time

Test group	Opacity value = Difference (t240 – t0) of opacity		Permeability at 490 nm (OD490)		In vitro irritancy score	Mean in vitro irritancy score
		Mean		Mean
Negative control	0	0.33	0.075	0.091	1.13	1.69
	1		0.119		2.79
	0		0.078		1.17
Positive control	127.67*		0.067*		128.68	124.79
	127.67*		0.055*		128.50
	114.67*		0.168*		117.19
Strontium neodecanoate	149.67*		1.622*		174.00	166.90
	131.67*		1.680*		156.87
	144.67*		1.677*		169.83

* corrected values

-With the negative control (saline) neither an increase of opacity nor permeability of the corneae could be observed (mean IVIS = 1.69).

- The positive control (10% (w/v) Benzalkonium chloride in saline) showed clear opacity of the corneae (mean IVIS =124.792).

Table 2: Historical data

	Positive control	Negative control
Mean IVIS	176.58	1.71
Standard deviation	41.85	0.76
Range of IVIS	62.60 - 292.29	0.00 – 3.00

Values of 206 studies with solid test items performed from February 2007 until December 2014 based on 0.5% sodium fluorescein solution in HBSS (w/v) and sodium fluorescein solution of 200 µL per well

Applicant's summary and conclusion

Interpretation of results:

Category 1 (irreversible effects on the eye)

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In conclusion, according to the current study and under the experimental conditions reported, strontium neodecanoate is serious eye damaging.