SILATRIZOLE

Endpoint summary

Description of key information

In a GPMT, Silatrizole (encoded "G4375") did not induce skin sensitization (OECD 406, GLP, Key study, Klimisch 1).
In a Buehler test, Silatrizole (encoded "G4375") did not induce skin sensitization (OECD 406, GLP, Key study, Klimisch 1).

Two GLP studies were available on the registered substance. No study was selected since both were negative and were of high quality (Klimisch score = 1).

 

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 13 November 1995 to 01 February 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study conducted in compliance with OECD Guideline 406 without any deviations.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

yes

Remarks:

Mixture of FCA:physiological saline was chosen instead of FCA only in order to decrease the site effects of FCA when applied alone

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

(16-06-1994)

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Adequate data from non-LLNA method is already available

Species:

guinea pig

Strain:

other: Himalayan white spotted (Ibm : GOHI ; SPF-quality guinea pigs)

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: BRL, Biological research Laboratories Ltd., Wölfertrasse 4, 4414 Füllinsdorf, Switzerland
- Age at study initiation: 5-7 weeks
- Weight at study initiation: Control and test group: 334-443 g; Range-finding test: 414-476 g
- Housing: Individually in Makrolon type-3 cages with autoclaved standard softwood bedding (“Lignocel”, Scill AG, CH-4132 Muttenz).
- Diet: Pelleted standard Nafag Ecosan 845 25W4, Batch n 94/95 and 108/95 guinea pig breeding/maintenance diet (“Nafag”, Nähr- und Futtermittel AG, CH-9202 Gossau), ad libitum.
- Water: community tap water from Itingen, ad libitum. Once weekly, additional supply of ascorbic acid (1g/l) via the drinking water.
- Acclimation period: One week for the control and test group. No acclimatization for the animals of the Range-finding study.


ENVIRONMENTAL CONDITIONS
- Temperature: 21 ± 3 ºC
- Humidity: 40-70%
- Air changes: 10-15 air changes per hour
- Photoperiod: 12 h dark / 12 h light

IN-LIFE DATES: From: 13 November 1995 To: 14 December 1995

Route:

intradermal and epicutaneous

Vehicle:

other: Corn oil / acetone (20/80)

Concentration / amount:

Range finding test:
- Intradermal induction exposure: 1, 3 and 5%
- Topical induction exposure: 60, 70, 80 and 85%

Main test:
- Intradermal induction exposure: 5%
- Topical induction exposure: 85%
- Topical challenge exposure: 85%

Route:

epicutaneous, semiocclusive

Vehicle:

other: Corn oil / acetone (20/80)

Concentration / amount:

Range finding test:
- Intradermal induction exposure: 1, 3 and 5%
- Topical induction exposure: 60, 70, 80 and 85%

Main test:
- Intradermal induction exposure: 5%
- Topical induction exposure: 85%
- Topical challenge exposure: 85%

No. of animals per dose:

- Range finding test: 6 males
- Main test: 10 males for negative control and 20 animals for treatment group

Details on study design:

RANGE FINDING TEST:
- Intradermal induction exposure: intradermal injections (0.1 ml/site) were made into the clipped flank of 2 animals at concentrations of 5, 3 and 1% of the test article in corn oil/acetone (20/80). The resulting dermal reactions were assessed 24 h later. A 5% dilution was selected for intradermal induction.
- Topical induction exposure: Both flanks of each of other 4 guinea pigs were clipped and shaved just prior to the application. The test substance at 60, 70, 80 and 85% in corn oil/acetone (20/80) was applied topically under 4 occlusive patches (covered by a strip of aluminum foil and firmly secured by elastic plaster and covered with impervious adhesive tape) per animal, saturated with the test article dilutions, and held in contact with the skin for 24 hours. The reaction sites were assessed 24 and 48 h after removal of the patches for erythema and oedema according to Draize scale. The 85% dilution was selected for the topical induction and challenge.

MAIN STUDY
A. INDUCTION EXPOSURE: INTRADERMAL
- No. of exposures: One
- Day of induction: Day 1
- Test group: 3 pairs of intradermal injections (0.1 mL each) of a mixture of 1:1 (v/v) of Freund’s Complete adjuvant (FCA) and physiological saline, test article at 5% in corn oil/acetone (20/80), test article at 5% in a 1:1 (v/v) of FCA and physiological saline.
- Control group: 3 pairs of intradermal injections (0.1 mL each) of a mixture of 1:1 (v/v) of FCA and physiological saline, corn oil/acetone (20/80), 1:1 (w/w) mixture of corn oil/acetone (20/80) and 1:1 (v/v) of FCA and physiological saline.
- Site: an area of dorsal skin from the scapular region (approximately 6x8cm) was clipped free of hair.

B. INDUCTION EXPOSURE: TOPICAL
- No. of exposures: One
- Day of induction: Day 8
- Exposure period: 48 h
- Test group: After a 24h-topical exposure to Sodium Lauryl sulfate (10% in paraffinum perliquidum), a occlusive patch (covered by a strip of aluminum foil and firmly secured by elastic plaster and covered with impervious adhesive tape) saturated with the test article (85% in corn oil/acetone (20/80)) was applied topically.
- Control group: After a 24h-topical exposure to Sodium Lauryl sulfate (10% in paraffinum perliquidum), a occlusive patch saturated with corn oil/acetone (20/80)) was applied topically.
- Site: Same intradermally injected area (an area of scapular region clipped free of hair)
- Frequency of applications: Single application
- Evaluation (h after removal of induction patch): 24 and 48 h


C. CHALLENGE EXPOSURE: TOPICAL
- No. of exposures: One
- Day of challenge: Day 22
- Exposure period: 24 h
- Test and control groups: Area of the left and right flanks of treated and control animals were clipped and cleared of hair and 2 occlusive patches (covered by a strip of aluminum foil and firmly secured by elastic plaster and covered with impervious adhesive tape) saturated with the test article (85% in corn oil/acetone (20/80)) (left flank) and the vehicle only (right flank) were applied topically.
- Site: left and right flanks treated with test item dilution and vehicle only, respectively.
- Evaluation (h after removal of challenge patch): 24 and 48 h

OTHER:
- Mortality/clinical signs (local and systemic): daily during observation period
- Body weight: at the beginning of the acclimatization period, at day one and at the termination of the test.
- A 24h-topical exposure to Sodium Lauryl sulfate (10% in paraffinum perliquidum) was performed before topical induction phase in order to induce skin irritation.
- The reaction sites were scored 24 and 48h after the removal of the patch for erythema and oedema according to Draize scale. The readings were made under artificial fluorescent light.

Challenge controls:

In challenge period, the control group was treated once with the vehicle and with the test item at 85% in vehicle.

Positive control substance(s):

yes

Remarks:

2-Mercaptobenzothiazol and α-hexylcinnamaldehyde

Positive control results:

In recent reliability check, 15% 2-Mercaptobenzothiazol in mineral oil and 3% α-hexylcinnamaldehyde in PEG 400 (positive historical controls) were found to induce an appropriate response in guinea-pig (95% of the animals at 48 h and 72 h and 75% of the animals at 48h and 45% at 72h, respectively).

Key result

Reading:

other: positive control

Hours after challenge:

48

Group:

positive control

Dose level:

15% 2-Mercaptobenzothiazol in mineral oil

No. with + reactions:

9

Total no. in group:

10

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

85% in corn oil/acetone (20/80)

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 85% in corn oil/acetone (20/80). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: none.

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

85% in corn oil/acetone (20/80)

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 85% in corn oil/acetone (20/80). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: none.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0 %

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0 %. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0 %

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0 %. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

- During the experimental period, none of the animals (control and treated groups) presented edema or erythema.

- No erythema or edema was observed after 48 and 72 h patch removal.

- One animal of the test group lost weight during the acclimatization period thus considered incidental.

- No symptoms of systemic toxicity were observed in the animals.

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

Under these test conditions, Silatrizole (encoded "G4375") is not classified as skin sensitiser according to the Regulation (EC) N° 1272-2008 (CLP).

Executive summary:

In a GLP Magnusson & Kligman maximisation study (GPMT) performed according to OECD Guideline 406, 20 male Himalayan white spotted guinea pigs were induced with three pairs of intradermal injections (0.1 mL each) of a mixture of 1:1 (v/v) of Freund’s Complete adjuvant (FCA) and physiological saline, test article at 5% in corn oil/acetone (20/80), test article Silatrizole (encoded "G4375") at 5% in a 1:1 (v/v) of FCA and physiological saline, on Day 0 on three different sites on an area of dorsal skin from the scapular region.

Control group of 10 males was intradermally induced (0.1 mL each)with 1:1 (v/v) of FCA and physiological saline, corn oil/acetone (20/80), 1:1 (w/w) mixture of corn oil/acetone (20/80) and 1:1 (v/v) of FCA and physiological saline.

On Day 7, a topic application of 10% sodium lauryl sulfate solution in paraffimun perliquidum was performed on the same area of injections.

On Day 8, a topic application was performed using a occlusive patch saturated with the test article (85% in corn oil/acetone (20/80)) (experimental group) or corn oil/acetone (20/80) (control group) held in contact to the tested area for 48 hours.

After a rest period of two weeks, on Day 22, challenge exposure began: two occlusive patches saturated with the test article (85% in corn oil/acetone (20/80)) or corn oil/acetone (20/80) were applied on the left and right flank of the animals (test and control), respectively. The test concentration for the main study was determined from a range-finding study using 6 animals (2 for intradermal induction and 4 for topical application).

No impact was observed in the study, since no skin reactions were observed in the animals during the challenge period. No skin reactions were noted at the challenge sites of the test or control group animals at the 48 or 72 h observations. Silatrizole produced a 0 % (0/10) sensitization rate and was considered to be a non-sensitizer to guinea pig skin. Positive control (15% 2-Mercaptobenzothiazol in mineral oil and 3% α-hexylcinnamaldehyde in PEG 400) exhibited evidence of sensitization. 

 

Under these test conditions, Silatrizole is not classified as skin sensitizer according to the Annex VI to the Regulation (EC) N° 1272-2008 (CLP).

Reference 2

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From 03 January 1996 to 25 April 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study conducted in compliance with OECD Guideline 406.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

(16-06-1994)

Type of study:

Buehler test

Justification for non-LLNA method:

Adequate data from non-LLNA method is already available

Species:

guinea pig

Strain:

other: Himalayan white spotted (Ibm : GOHI ; SPF-quality guinea pigs)

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: BRL, Biological research Laboratories Ltd., Wölfertrasse 4, 4414 Füllinsdorf, Switzerland
- Age at study initiation: 5-7 weeks
- Weight at study initiation: Control and test group: 306 - 432 g; Irritation screen: 341 - 413g
- Housing: Individually in Makrolon type-3 cages with autoclaved standard softwood bedding (“Lignocel”, Schill AG, CH-4132 Muttenz).
- Diet: Pelleted standard Nafag Ecosan 845 25W4, Batch n. 108/95 and 118/95 guinea pig breeding/maintenance diet (“Nafag”, Nähr- und Futtermittel AG, CH-9202 Gossau), ad libitum.
- Water: community tap water from Itingen, ad libitum. Once weekly, additional supply of ascorbic acid (1g/l) via the drinking water.
- Acclimation period: One week for the control and test group. One day for the animals used in the irritation screen.


ENVIRONMENTAL CONDITIONS
- Temperature: 21 ± 3 ºC
- Humidity: 40-70%
- Air changes: 10-15 air changes per hour
- Photoperiod: 12 h dark / 12 h light

IN-LIFE DATES: From: 03 January 1996 To: 12 February 1996

Route:

epicutaneous, occlusive

Vehicle:

other: Corn oil / acetone (20/80)

Concentration / amount:

Range finding test:
- Topical induction exposure: 60, 70, 80 and 85%

Main test:
- Topical induction exposure: 85%
- Topical challenge exposure: 85%

Route:

epicutaneous, occlusive

Vehicle:

other: Corn oil / acetone (20/80)

Concentration / amount:

Range finding test:
- Topical induction exposure: 60, 70, 80 and 85%

Main test:
- Topical induction exposure: 85%
- Topical challenge exposure: 85%

No. of animals per dose:

- Irritation screen: 4 animals
- Main test: 10 animals for negative control group and 20 animals for treatment group

Details on study design:

RANGE FINDING TESTS (Irritation screen):
Four different concentrations were used on each animal for a 6 hour period: 60, 70, 80 and 85% (w/w) in corn oil/acetone (20/80). The animals were put in the restrainer and the patches were applied to the clipped surface. The patch appliance was occluded with a rubber dental dam. Six hours later, the rubber dental dams and patches were removed and the animals were taken away from the restrainers. The animals were depilated 21 hours after patches had been removed. The reaction sites were assessed 24 h (± 2 hours) and 48h (± 2 hours) after removal of the patches for erythema and oedema according to Draize scale. The 85% dilution was selected for the topical induction and challenge.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Day of induction: Day 1, 8 and 15
- Exposure period: 6 h
- Test groups: The animals were put in the restrainer and a patch containing the test article at 85% (w/w) in corn oil/acetone (20/80) (0.1 g/25mm Hill Top Chamber) was applied. The patch appliance was occluded with a rubber dental dam. Six hours later, the rubber dental dams and patches were removed and the animals were taken away from the restrainers.
- Control group: the control group was treated with the vehicle corn oil/acetone (20/80) alone (0.5 ml/25mm Hill Top Chamber).
- Site: left shoulder. The repeated application was performed at the same site.
- Frequency of applications: Each animal received one patch per week for three weeks which remained in place for approximately 6 hours each. The interval between exposures was 7 days.
- Evaluation (h after removal of induction patch): 24 hours (± 2 hours)

B. CHALLENGE EXPOSURE
- No. of exposures: One
- Day of challenge: Day 29
- Exposure period: 6 h
- Test and control groups: the animals previously exposed during the induction period were challenged two weeks after the last induction exposure using the highest non-irritating concentration of 85% (w/w) in corn oil/acetone (20/80) under occlusive patch (0.1 g/25mm Hill Top Chamber).
- Site: naïve skin site of the left posterior quadrant of the side and back of the animals.
- Evaluation (h after removal of challenge patch): The animals were depilated 21 hours after patches had been removed and the reaction sites were assessed 24 h (± 2 hours) and at 48h (± 2 hours) after removal of the patches for erythema and oedema according to Draize scale.

OTHER:
- Mortality/clinical signs (local and systemic): daily during treatment/observation period
- Body weight: at the beginning of the acclimatization period, at day one and at the termination of the test.
- Clinical signs: daily during the treatment and observation period.
- Grading of all animals was done by positioning the animal under true-light (Osram, 58 Watt, tight quality TLD).
- Depilatory procedure: The animals were depilated 21 hours after patches had been removed, using an approved depilatory cream (VEET Cream, Reckitt & Colman AG, CH-4123 Allschwil). The depilatory was placed on the patch sites and surrounding areas, and left on for 3-5 minutes. It was then thoroughly washed off with a stream of warm, running water. The animals were then dried with a disposable towel, and returned to their cages.

Challenge controls:

In challenge period, the control group was treated with the test item at 85% in vehicle.

Positive control substance(s):

yes

Remarks:

α-hexylcinnamaldehyde

Positive control results:

In the last reliability check, 5% α-hexylcinnamaldehyde in PEG 400 (positive historical controls) were found to induce an appropriate response in guinea-pig (58% of the animals)

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

85% in corn oil/acetone (20/80)

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

None

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 85% in corn oil/acetone (20/80). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: None.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

85% in corn oil/acetone (20/80)

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

None

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 85% in corn oil/acetone (20/80). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: None.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: None.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: None.

- No animal died during the course of the treatment period.

- No systemic effects were observed dunring the study.

- The body weight gain of the animals was not affected during the study.

- No skin reaction was observed in the control group treated with corn oil/acetone (20/80) and in the test group treated with the test item at 85% (w/w) in corn oil/acetone (20/80), in both the induction and challenge periods.

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

Under these test conditions, Silatrizole (encoded "G4375") is not classified as skin sensitiser according to the Regulation (EC) N° 1272-2008 (CLP).

Executive summary:

In a modified Buehler study performed according to OECD Guideline 406, twenty female animals of the test group were treated topically under occlusive patches with Silatrizole (encoded "G4375") at 85% (w/w) in corn oil/acetone (20/80) and 10 female animals of the control group were treated with corn oil/acetone (20/80) once a week for a 3 week induction phase. Two weeks after the final induction application the animals of both groups were challenged with the same test substance used for induction, at the same concentration of 85% (w/w) in corn oil/acetone (20/80).

None of the animals of the test group were observed with positive reactions (grade of 0 and ± are considered to be non-significant responses, whereas those of 1 and greater are considered to be significant) after challenge performed with the highest non-irritating concentration of test item, at 85% (w/w) in corn oil/acetone (20/80). No reactions were observed in the control group treated in the same conditions during the challenge phase.

Under these test conditions, Silatrizole is not classified as skin sensitizer according to the Annex VI to the Regulation (EC) N° 1272-2008 (CLP). This study is considered asacceptable and satisfies the requirement for sensitization endpoint.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

In a GLP Magnusson & Kligman maximisation study (GPMT) performed according to OECD Guideline 406, the test article diluted at 5% in corn oil/acetone (20/80) was administered by injection for intradermal induction. On Day 7, a topic application of 10% sodium lauryl sulfate solution in paraffimun perliquidum was performed. On Day 8, a topic application was performed using a occlusive patch saturated with the test article (85% in corn oil/acetone (20/80)) for 48 hours. For the challenge, two occlusive patches saturated with the test article (85% in corn oil/acetone (20/80)) or corn oil/acetone (20/80) were applied on the left and right flank of the animals, respectively. The test concentration for the main study was determined from a range-finding study. The sensitivity and validity of the experiment was confirmed with known sensitizers, 15% 2-Mercaptobenzothiazol in mineral oil and 3% α-hexylcinnamaldehyde in PEG 400.

No skin reactions were noted at the challenge sites of the test or control group animals at the 24 and 48 h observations.

 

A modified Buehler study performed according to OECD Guideline 406, twenty female animals of the test group were treated topically under occlusive patches with Silatrizole (encoded "G4375") at 85% (w/w) in corn oil/acetone (20/80) and 10 female animals of the control group were treated with corn oil/acetone (20/80) once a week for a 3 week induction phase. Two weeks after the final induction application the animals of both groups were challenged with the same test substance used for induction, at the same concentration of 85% (w/w) in corn oil/acetone (20/80). The sensitivity and validity of the experiment was confirmed with a known sensitizer, 5% α-hexylcinnamaldehyde in PEG 400.

This test also gave negative results with none of the animals observed for positive reactions.

 

On conclusion, there was no evidence of sensitisation in the two reliable studies available.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

As the substance is not expected to be a skin sensitizer in the two reliable studies available, the substance is not classified as skin sensitizer according to the Regulation (EC) N° 1272 -2008 (CLP).

No data was available regarding respiratory sensitization.