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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin corrosion: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-01-04 - 2017-02-23
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)
Version / remarks:
2016-07-29
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
impurity
Type:
impurity
Test material form:
solid: bulk
Details on test material:
This composition is the usual techical grade of AlzChem AG. It will be used when test substance has this composition (or is very closed) or no specific information is available

In vitro test system

Test system:
human skin model
Source species:
human
Cell type:
other: NHEC: normal human-derived epidermal keratinocytes
Justification for test system used:
The EpiDerm(TM) Skin Model is a well established organotypic, three-dimensional model of the human epidermis and is used for in vitro experiments many years. It is known for its similaryty to huaman skin.
Vehicle:
water
Details on test system:
The test was carried out with the reconstituted three-dimensional human skin model EpiDerm(TM) (MatTek). This skin model consists of normal human epidermal keratinocytes (NHEK) which have been cultured to form a multilayered, highly differentiated model of the human epidermis. The NHEK are cultured on chemically modified, collagen-coated cell culture inserts (Millicell(R)). The EpiDerm(TM) epidermis model exhibits in vivo-like morphological and growth characteristics which are uniform and highly reproducible. It consists of organised basal, spinous and granular layers and a multi-layered stratum corneum analogous to patterns found in vivo.
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
Negative control: 50 µL distilled Water
Positive control: 50 µL 8 N KOH
Test Item: 25 mg + 25 µL H2O
Duration of treatment / exposure:
3 min; 60 min
Number of replicates:
4 per dose group
2 repliocates for each treatment period

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
3 min
Value:
ca. 97.5
Vehicle controls valid:
not examined
Negative controls valid:
yes
Positive controls valid:
yes
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
60 min
Value:
ca. 77.5
Vehicle controls valid:
not examined
Negative controls valid:
yes
Positive controls valid:
yes

Applicant's summary and conclusion

Interpretation of results:
other: non-corrosive
Conclusions:
In the study under the given conditions the test item showed no corrosive effects. The test item is classified as "non-corrosive".
Executive summary:

In the present study the skin corrosivity of Thioctic Acid was analysed. Since corrosive chemicals are cytotoxic after a short tim exposure to the stratum corneum of the epidermis the cytotoxic effects of the test item on EpiDerm(TM), a reconstituted three-dimensional human epidermis model, were determined. Hereby, the test item was applied topically. Cytotoxicity is expressed as the reduction of mitochondrial dehydrogensase activity measured by formazan production from MTT after a 3 min and 60 min exposure period and compared to those of the concurrent negative controls.