Registration Dossier

Administrative data

Endpoint:
dermal absorption in vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No GLP

Data source

Reference
Reference Type:
publication
Title:
Percutaneous absorption of aliphatic compounds.
Author:
Iwata Y, Moriya Y, Kobayashi T
Year:
1987
Bibliographic source:
Cosmet. Toiletries 102(2): 53-68.

Materials and methods

Principles of method if other than guideline:
¹⁴C labelled test substances were applied to the dorsal skin using a plaster for a 24 hour period. Immediately following application each animal was placed in a container to measure expiratory excretion. At the end of the exposure period the treated area of skin was excised and dissolved using tissue  solubiliser. The carcass was homogenised in a blender with sodium hydroxide. An aliquot of the homogenate was then dried and combusted for determination of radioactivity. The effect of different solvents and concentration of the solvent was also investigated. The role of skin irritation in absorption of test substance was examined.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Liquid
Details on test material:
14C-cetyl alcohol >98% pure
Radiolabelling:
yes

Test animals

Species:
mouse
Strain:
other: HR/De
Sex:
not specified

Administration / exposure

Type of coverage:
occlusive
Vehicle:
other: tested in three solvent vehicles: TEC, castor oil and squalane.
Duration of exposure:
24 hours
Doses:
Up to 5% concentration in three vehicles.
No. of animals per group:
3
Control animals:
no

Results and discussion

Percutaneous absorption
Dose:
5%
Parameter:
percentage
Absorption:
ca. 1 %
Remarks on result:
other: 24 hours

Any other information on results incl. tables

The percentage absorbance of dose 14C-cetyl alcohol (hexadecan-1-ol) = ca 1%. At least 65% of the absorbed dose is excreted as carbon dioxide in the expired air.

When tested diluted in solvent vehicles, the degree of absorption was influenced by the concentration and the type of solvent that was used.

For n-cetyl alcohol in squalene, approximately 2% of the applied dose was absorbed at the 0.5%, reducing with increased concentration to 1% of the applied dose at 5%.

For n-cetyl alcohol in castor oil and in TEC (triethyl citrate), slightly less was absorbed at the applied concentrations of 0.5 and 5%

Applicant's summary and conclusion

Conclusions:
Of a dose of 1-14C-cetyl alcohol (5%) in squalene applied to the skin of nude mice for 24 hours under occlusive conditions, 1 % was absorbed.
Executive summary:

Of a dose of 5% 1-14C-cetyl alcohol applied to the skin of nude mice for 24 hours, 1% was absorbed.