Registration Dossier

Administrative data

Endpoint:
dermal absorption in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Deatailed reference of a secondary source.

Data source

Reference
Reference Type:
secondary source
Title:
Final report on the safety assessment of Glycolic acid, NH4, Ca, K, Na glycolates; methyl, ethyl, propyl, and butyl glycolates; Lactic acid, NH4, Ca, K, Na and tea-lactates, methyl, ethyl, isopropyl, butyl , lauryl, myristyl, and cetyl lactates.
Author:
Cosmetic Ingredient Review Panel
Year:
1998
Bibliographic source:
International Journal of Toxicology, 17(Suppl. 1):1-3

Materials and methods

Principles of method if other than guideline:
Kraeling, M. E. K., and Bronaugh, R. L. 1996. In vitro percutaneous absorption of alpha hydroxy acids in human skin. Unpublished data submitted to CIR by FDA. 20 pp. (Available for review: Director, Cosmetic Ingredient Review, 1101 17th Street, NW, Washington, DC 20036, USA).
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Radiolabelling:
yes

Administration / exposure

Type of coverage:
other: not applicable: in vitro test
Details on in vitro test system (if applicable):
The in vitro percutaneous absorption of Lactic Acid was determined using human abdominal skin. The skin was mounted in flow-through diffusion cells. Skin viability was maintained and barrier integrity was confirmed prior to formulations that were prepared to give an average dose of 0.55 µCi of 14C radioactivity per cell. The emulsions were applied to the skin at 3 mg/cm2 of exposed skin in the diffusion cells (exposed skin = 0.64 cm2). At the end of each experiment, the skin was washed and rinsed three times, and then tape stripped 10 times to remove the stratum corneum. The remaining epidermis was separated from the dermis using heat. The absorbed radioactivity in the 6-h receptor fluid fractions and the skin layers was measured by liquid scintillation counting. The percutaneous absorption of 5% Lactic Acid in 2% PEG-100 stearate and 1% laureth-4 was determined at pH 3 and 7 using skin samples from three subjects for each pH.

Results and discussion

Absorption in different matrices:
Total absorption was 30.4 % at pH 3 and 9.7 % at pH 7. With the pH 3 formulation, the amount of radioactivity found in the receptor fluid, stratum corneum, viable epidermis, and dermis was 3.6, 6.3, 6.6, and 13.9%, respectively.

Applicant's summary and conclusion