Determination of 8-methoxypsoralen levels in plasma and skin suction blister fluid by a new sensitive fluorodensitometric method.
An improved fluorodensitometric assay for the determination of 8-methoxypsoralen (8-MOP) in plasma is described. Because of its low limit of detection (below 1 ng/spot) this method is suitable to determine the drug in skin suction blister fluid, too. The standard deviation of the procedure is 6.4% or less. Plasma and skin blister fluid levels of 8-MOP are determined 2 h following oral administration of 40-60 mg 8-MOP. They range from 0-239 ng/ml and 0-163 ng/ml, respectively. A rather close correlation (r = 0.91) between these two parameters could be observed. Thus, in cases with relatively high plasma levels sufficient skin levels can be predicted. If further investigations would prove, however, that a distinct concentration threshold required for therapeutic success exists--and recent experiments with fibroblast cultures imply that--skin blister fluid level determinations would seem highly desirable when plasma levels let us expect skin levels in the critical range. In general determination of 8-MOP skin blister fluid levels can be looked upon as a model for the evaluation of drug skin levels after systemic application in man.
D000328:Adult; D000368:Aged; D001768:Blister; D003720:Densitometry / Q000379:methods*; D005122:Exudates and Transudates / Q000032:analysis*; D005260:Female; D005470:Fluorometry / Q000379:methods*; D006801:Humans; D008297:Male; D008730:Methoxsalen / Q000032:analysis* / Q000097:blood; D008875:Middle Aged; D010267:Parapsoriasis / Q000188:drug therapy / Q000378:metabolism; D011565:Psoriasis / Q000188:drug therapy / Q000378:metabolism; D013396:Suction
D008730:Methoxsalen