Bis(glycinato-N,O)zinc

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: The skin irritation potential of zinc glycinate was examined on male Japanese albino rabbits (Kbl: JW, SPF) using the Draize method.

- Short description of test conditions: The test substance was made into a fine powder and was mixed with Japanese pharmacopoeia water for injection (referred to as water for injection). This mixture was then occlusively applied on the intact as well as the abraded skin of the animal for 24 hours. The abrasion was inflicted by an injection needle through the stratum corneum in a criss cross lattice.

- Parameters analysed/observed: Skin reaction was followed throughout the experiment. At the end of exposure, the erythema and oedema scores were determined. Animal symptom observations were then followed 7 days after the end of exposure.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Bis(glycinato-N,O)zinc

EC Number:

238-173-1

EC Name:

Bis(glycinato-N,O)zinc

Cas Number:

14281-83-5

Molecular formula:

C4H8N2O4Zn

IUPAC Name:

Zinc bis(aminoacetate)

Test material form:

solid: particulate/powder

Details on test material:

Batch number: 4002
Pourcentage of Zinc: 28.2%
Molecular Weight: 231.52

Specific details on test material used for the study:

Appearance: White powder
Storage Conditions: Room temperature, dark location
Temperature: 13.8-25.2°C

Test animals

Species:

rabbit

Strain:

other: Japanese Albino (Kbl: JW)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Kitayama Labes Co., Ltd.
- Age at study initiation: 11 weeks
- Weight at study initiation: 2.44 - 2.62kg
- Housing: Suspension type aluminium cage (32W x 48D x 33H cm, with wire mesh cage floor, Tokiwa Kagaku Kikai Co., Ltd.)
Material was sterilized using steam and exchanged once 7 days after the arrival of the animals.
- Diet (e.g. ad libitum): Solid feed for laboratory animals (LRC4, Oriental Yeast Co., Ltd.) ; Free feeding ; Leftovers were disposed of when exchanging the feeder and new feed was provided.
- Water (e.g. ad libitum): Tap water filtered with a 5μm filter and subsequent ultraviolet irradiation treatment ; Free water feeding ; Inspection of water quality was carried out periodically (twice a year) by the Diamond Analysis Center Co., Ltd. (now Mitsubishi Chemical Analytech Co., Ltd.). Conformation to the criteria of the standard operating procedure manual, which were based on water supply regulations, was assured.
- Acclimation period: To confirm the good health of the animals, the general condition of each animal was observed once per day for 5 days and the weight was measured on the day of arrival and the end of quarantine. The acclimatization was continued for a day in the time between the end of quarantine and the beginning of the administration and the general condition was checked once per day.
No abnormalities were found during the quarantine and acclimatization period.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Actual value 20.7-24.3°C (permissible range 19.0-25.0°C)
- Humidity (%): Actual value 44.4-70.1% (permissible range 35.0-75.0%)
- Air changes (per hr): 6-20 air changes per hour, “All Fresh Air” supply
- Photoperiod (hrs dark / hrs light): 12 hours light per day, between 7:00 and 19:00

Test system

Type of coverage:

occlusive

Preparation of test site:

other: Intact skin and abraded skin

Vehicle:

water

Controls:

yes, concurrent vehicle

Amount / concentration applied:

PREPARATION OF THE TEST SUBSTANCE
The preparation was conducted extemporaneously under yellow fluorescent light.
The used test substance was a powder prepared by first fine grinding in an agate mortar and then passing it through a sieve (As One Corporation, standard: 100 mesh). An amount of 0.5 g each was weighed out for the administration to the animals (2 locations of administration per animal X 3 animals). The weighed amount of the test substance (powder) was used after mixing it with 0.1 ml of Japanese pharmacopoeia water for injection (Otsuka Pharmaceutical Factory, Inc., lot number K5C71, referred to as water for injection).


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 g/ location (amount of administered test substance)
- Number of Doses and Hours of Exposure: once, 24-hour exposure (occlusive application)
- Method of Administration: 2 locations for the administration were created on each side of the back of the animal, resulting in 4 locations total.
2 locations each were defined for the intact and the abraded skin. For the abraded skin a 23G injection needle was used to create a criss cross lattice of abrasions through the stratum corneum.
A gauze patch (approx. 2.5 x 2.5 cm, 6 cm2, 3 layers) impregnated with the test substance was applied to one location each for the intact and abraded skin. On the remaining location on the intact as well as abraded skin, a gauze patch impregnated with 0.1 ml water for injection was applied (the same amount of water for injection as used to mix with the test substance). The patch was loosely fixed with a 1 x 7 cm adhesive bandage in a X pattern. Following that, the patch was covered with a non-transparent sheet (plastic sheet) and further wrapped with a semi-transparent elastic bandage. The animals were made to wear clothes designed to keep the patch in place (in-house product) and a loose contact of the patch and the skin was assured.
After the exposure time, the patch was removed and the administration area was flushed with moderately warm water (actual value: 35.8 – 38.5°C).
To protect the area of administration a cone (Elizabethan collar) was used on all animals from the time right after the administration until the end of the observation.

Duration of treatment / exposure:

24 hours

Observation period:

7 days

Number of animals:

3 animals

Details on study design:

OBSERVATION OF SKIN REACTION
The skin reaction at the location of the administration was observed with the naked eye 24 hours (18 or 20 minutes after the removal of the patch), 48 hours, 72 hours and 7 days after the administration. The observation was concluded after 7 days, because no skin reaction was observed at the area of test substance administration in any animal at that point. Furthermore, a photograph of a representative animal (animal number 10101) was taken at each observation.

SCORE EVALUATION
The skin reaction was evaluated according to the Draize criteria.

CLASSIFICATION OF THE EXTENT OF IRRITATION
For every area of administration (intact and abraded skin) the score for erythema and eschar formation, and oedema, after 24 and 72 hours were added together for all animals. This value was then divided by the number of observations, 6 (3 animals x 2 points in time), to get the Primary Irritation Index (P.I.I.). This value was used to classify the extent of the primary skin irritation of the test substance based on the Draize method.

OBSERVATION OF GENERAL CONDITION
The general condition of the animals was observed once per day from the day of the administration until the end of the observation of the skin reaction.

BODY WEIGHT
The body weight of all of the animals was measured directly before the administration, and 72 hours as well as 7 days after the administration. An animal scale (EB-16KS, Shimadzu Corporation) was used for weighing.

HANDLING OF THE ANIMALS AFTER THE END OF OBSERVATION
The animals used in this test were euthanized via intravenous injection of a large amount (approx. 2 times the standard amount of anaesthetic) of pentobarbital sodium salt (Nembutal, Sumitomo Dainippon Pharma Co., Ltd.) into the pinna after the end of the observation.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

primary dermal irritation index (PDII)

Basis:

mean

Time point:

other: mean

Score:

ca. 0.8

Reversibility:

fully reversible

Remarks on result:

other: Same results for Intact skin and abraded skin

Remarks:

Same results for Intact skin and abraded skin

Results 2

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

ca. 1

Reversibility:

fully reversible

Remarks on result:

other: Same results for Intact skin and abraded skin

Remarks:

Same results for Intact skin and abraded skin

Results 3

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

7 d

Score:

ca. 0

Remarks on result:

no indication of irritation

Remarks:

Same results for Intact skin and abraded skin

Results 4

Irritation parameter:

edema score

Basis:

animal #1

Time point:

24/48 h

Score:

ca. 1

Reversibility:

fully reversible

Remarks on result:

other: Same results for Intact skin and abraded skin

Remarks:

Same results for Intact skin and abraded skin

Results 5

Irritation parameter:

edema score

Basis:

animal #1

Time point:

24 h

Score:

ca. 1

Reversibility:

fully reversible

Remarks on result:

positive indication of irritation

Results 6

Irritation parameter:

edema score

Basis:

animal #1

Time point:

48 h

Score:

ca. 1

Reversibility:

fully reversible

Remarks on result:

positive indication of irritation

Results 7

Irritation parameter:

edema score

Basis:

animal #1

Time point:

other: 72h and 7 d

Score:

ca. 0

Remarks on result:

no indication of irritation

Remarks:

Same results for Intact skin and abraded skin

Results 8

Irritation parameter:

edema score

Basis:

animal #1

Time point:

72 h

Score:

ca. 0

Remarks on result:

no indication of irritation

Results 9

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

24/48 h

Score:

ca. 1

Reversibility:

fully reversible

Remarks on result:

other: Same results for Intact skin and abraded skin

Remarks:

Same results for Intact skin and abraded skin

Results 10

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

other: 72 h and 7 d

Score:

ca. 0

Remarks on result:

no indication of irritation

Remarks:

Same results for Intact skin and abraded skin

Results 11

Irritation parameter:

edema score

Basis:

animal #2

Time point:

other: 24/48/72 h and 7 d

Score:

ca. 0

Remarks on result:

no indication of irritation

Remarks:

Same results for Intact skin and abraded skin

Results 12

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

24/48 h

Score:

ca. 1

Reversibility:

fully reversible

Remarks on result:

other: Same results for Intact skin and abraded skin

Remarks:

Same results for Intact skin and abraded skin

Results 13

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

other: 72 h and 7 d

Score:

ca. 0

Remarks on result:

no indication of irritation

Remarks:

Same results for Intact skin and abraded skin

Results 14

Irritation parameter:

edema score

Basis:

animal #3

Time point:

other: 24/48/72 h and 7 d

Score:

ca. 0

Remarks on result:

no indication of irritation

Remarks:

Same results for Intact skin and abraded skin

Irritant / corrosive response data:

TEST SUBSTANCE APPLICATION AREA
(1) intact skin area
24 hours after the administration, a score of 1 for erythema could be confirmed in all animals, as well as a score of 1 for oedema in 1 animal. These symptoms disappeared 72 hours after the administration in 2 animals and after 7 days for the other animal.
(2) abraded skin area
24 hours after the administration, a score of 1 for erythema could be confirmed in all animals, as well as a score of 1 for oedema in 1 animal. These symptoms disappeared 72 hours after the administration in 2 animals and after 7 days for the other animal.

WATER OF INJECTION APPLICATION AREA
(1) intact skin area
No skin reaction was found in any animal.
(2) abraded skin area
No skin reaction was found in any animal.

CLASSIFICATION OF EXTENT OF PRIMARY SKIN IRRITATION
The calculated values for the Primary Irritation Index (P.I.I.) was 0.8 for the administration of the test substance on the intact as well as the abraded skin. Using this value, the extent of primary skin irritation can be classified as “mildly irritating” for the intact as well as the abraded skin.

Other effects:

GENERAL CONDITION
No abnormalities were found in any animal during the observation time.

BODY WEIGHT
72 hours after the administration, a slight weight decrease was confirmed in 2 animals; however, an abnormal weight fluctuation with possible influence on the evaluation of the test results was not found.

Applicant's summary and conclusion

Interpretation of results:

Category 3 (mild irritant) based on GHS criteria

Conclusions:

The primary skin irritation of zinc glycinate was examined.
Concluding from the results, the skin irritation of zinc glycinate in rabbits is classified as mildly irritating under the conditions of this test.

Executive summary:

The primary skin irritation of zinc glycinate was examined.
The test substance was made into a fine powder and mixed with water for injection. This mixture was then occlusively applied on the intact as well as the abraded skin of the animal for 24 hours. The abrasion was inflicted by an injection needle through the stratum corneum in a criss cross lattice.
Resulting from the 24-hour exposure, the administration of the test substance on the intact skin lead to a score of 1 for erythema in all animals and 1 for oedema in 1 animal. These symptoms disappeared after 72 hours in 2 of the animals and 7 days in the other animal. For the abraded skin, a score of 1 for erythema in all animals and 1 for oedema in 1 animal were also confirmed. These symptoms disappeared after 72 hours in 2 of the animals and 7 days in the other animal.
The Primary Irritation Index (P.I.I.) at the area of the administration of the test substance was 0.8 for the intact skin as well as the skin with abrasions. When classifying the extent of skin irritation based on this value, it is “mildly irritating” for the intact as well as the abraded skin. In contrast, no skin reaction was found in any of the animals at the area of the administration of water for injection on the intact as well as abraded skin.
72 hours after the administration a slight decrease in body weight was noted in 2 animals, however this is a change found often in this type of test and is thought to be caused by the stress resulting from the series of treatments. It is thus assumed to have no influence on the test evaluation.
Concluding from the results above, the skin irritation of zinc glycinate in rabbits is classified as mildly irritating under the conditions of this test.