title: 8-Methoxypsoralen serum levels in poor responders to photochemotherapy. Importance of drug formulation and individual factors.
abstract: 8-Methoxypsoralen (8-MOP) serum levels of psoriatic patients poorly responsive to photochemotherapy (PUVA) treatment (problem cases) were determined by the HPLC method with 11 single blood probes over 8 hours. Abnormally low or deviated serum levels were found in 7 of 11 PUVA problem patients. There was a great interindividually different first-pass effect for 8-MOP in dependence on the galenic formulation of the 8-MOP brand; therefore, the change to another 8-MOP brand with a modern galenic formulation led only to a slight increase of serum levels, and consequently an increase in the 8-MOP dosage was necessary. It is important to be cautious at this point because patients may show an unproportional increase of 8-MOP serum levels due to the individually limited capacity of biotransformation. The studies of the authors reaffirm the necessity of the determination of 8-MOP serum levels in problem cases of PUVA therapy.
authors.affiliation: Department of Dermatology, University Leipzig, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Walther
authors.forename: U F
authors.initials: UF
authors.lastname: Haustein
mesh_terms: D001682:Biological Availability; D001769:Blood; D002626:Chemistry, Pharmaceutical; D006801:Humans; D008730:Methoxsalen / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry / Q000493:pharmacokinetics; D011701:PUVA Therapy; D010778:Photochemotherapy; D013997:Time Factors
chemical_list: D008730:Methoxsalen