P. Buchan et al., REPEATED TOPICAL ADMINISTRATION OF ALL-TRANS-RETINOIC ACID AND PLASMA-LEVELS OF RETINOIC ACIDS IN HUMANS, Journal of the American Academy of Dermatology, 30(3), 1994, pp. 428-434
Background: Vitamin A ingestion raises plasma levels of several potent
ially teratogenic retinoic acids (RAs) with all-trans and 13-cis confi
guration, but definitive data concerning the consequences of topical a
dministration of all-trans-RA are lacking. Objective: The study object
ive was to investigate the potential for inducing systemic activity af
ter topical administration of 0.025% all-trans-RA by measuring plasma
retinoid levels. Methods: Plasma levels of all-trans-RA, 13-cis-RA, an
d 4-oxo-13-cis-RA were measured in four healthy subjects before, durin
g, and after 14 daily topical applications of all-trans-RA. Results: T
opical administration of all-trans-RA did not significantly increase p
lasma levels of all-trans-RA, 13-cis-RA, and 4-oxo-13-cis-RA. Signific
ant decreases in levels of these RAs observed during the night may ref
lect diurnal variations of retinoid metabolism or lowered absorption o
f dietary vitamin A. Conclusion: Diurnal and nutritional factors influ
ence plasma levels of endogenous retinoids to a greater extent than to
pical administration of all-trans-RA at doses used for acne therapy, w
hich on the basis of these results appears unlikely to induce systemic
effects.