Abstract:
Correlation of serum 8-methoxypsoralen and UVA photosensitivity in Thai psoriatic patients were evaluated in 21 patients treated with PUVA therapy. Blood samples were drawn at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 6, 8, 10, 12 hours after drug administration and serum drug concentrations were determined by using High Pressure Liquid Chromotography (HPLC). Test of skin photosensitivity were done at 2, 2.5, 3, 3.5, 4 hours after drug administration. The result of the study shows that time of peak serum concentration (Tmax) is 3.09+_0.23 (1-4) hours and peak serum concentration (Cmax) is 176.16+_15.62 (84-302.04) ng/ml. Half life of the drug is 3.25+_0.33 (1.1-4.89) hours. The elimination rate constant (Ke) is 0.25+_0.04 (0.14-0.63) hour-1. The correlation between peak serum concentration and minimal phototoxic dose (MPD) was found ; r = -0.44 (p<0.05)