[Pharmacokinetic comparison of 3 8-methoxypsoralen preparations and clinical aspects]

In order to register the inter- and intraindividual variability of serum levels of 8-methoxypsoralen (MOP) (Oxsoralen, n = 12; Geroxalen, n = 46; Mopsoralen, n = 30), we investigated a total of 1,276 serum samples obtained at 11 patient appointments over 8 h in 88 patients and compared the individual serum concentrations - time curves with the pharmacokinetic parameters Cmax (maximal serum concentration) on the time tmax, as well as the AUC value (area under the curve) as a parameter of bioavailability. The individual serum concentration value showed a high interindividual variability (Oxsoralen Cmax: 47-473 ng.ml-1; Geroxalen Cmax: 37-416 ng.ml-1 and Mopsoralen Cmax: 44-300 ng.ml-1) and preparation specific differences (Oxsoralen Cmax: 188 +/- 125 ng.ml-1; tmax: 2.0 +/- 0.6 h; AUC: 461 +/- 322 ng.ml-1.h; Geroxalen Cmax: 193 +/- 87 ng.ml-1; tmax: 0.9 +/- 0.4 h; AUC: 290 +/- 198 ng.ml-1.h; Mopsoralen Cmax: 164 +/- 71 ng.ml-1; tmax: 1.7 +/- 0.5 h; AUC: 389 +/- 221 ng.ml-1.h). On repeated administration of Geroxalen (n = 16) and Mopsoralen (n = 12), minimal intraindividual distributions were noted, so the mean serum concentration curves did not show a significant difference. The importance of 8-MOP serum level determinations for better puva therapy, particularly in therapeutic failure in problem cases, is discussed.