Background: Previous studies have shown important inter-and intraindiv
idual variations in bioavailability of 8-methoxypsoralen (8-MOP) under
the influence of factors that are not yet known with certainty. Howev
er, they seem to be independent of age, sex and concomitant retinoid a
dministration for RePUVA whereas the influence of diet remains controv
ersial. Objective: The purpose of this study was to investigate a poss
ible effect of metoclopramide on the bioavailability of 8-MOP since th
ese drugs are frequently combined to prevent nausea, a common side eff
ect of systemic 8-MOP. Methods: After a standard breakfast and the ing
estion of 8-MOP plasma kinetics of 8-MOP were assessed in 6 healthy vo
lunteers at 0, 1, 1.30, 1.45, 2, 2.15, 2.30, 3 and 4 h after drug inge
stion. This procedure was repeated 3 weeks later by associating metocl
opramide with 8-MOP. Plasma determinations of 8-MOP were performed usi
ng high-pressure liquid chromatography. Results: Time and peak value o
f maximum plasma 8-MOP concentration (T-max, C-max) ranged from 1 to 3
h and from 124 to 540 ng/ml, respectively. Individual values of the a
rea under the curve of time-related 8-MOP concentration were between 2
84 and 1,158 ng.h/ml. Concomitant intake of 8-MOP with metoclopramide
did not significantly influence these 3 pharmacokinetic values. Conclu
sion: Our results confirm the important interindividual variability of
the pharmacokinetics of 8-MOP. Associating 8-MOP with metoclopramide
does not alter the pharmacokinetic values of 8-MOP and should not requ
ire any change in PUVA treatment.