Serum levels of 8-methoxypsoralen: difference between two oral methods of administration.

Serum levels of 8-methoxypsoralen were determined in six human volunteers after two different methods of oral administration. 8-Methoxypsoralen was given as an aqueous solution and as powder in gelatin capsules. The area under the curve (AUC) values were higher (P < 0.05) for the solution than for the capsules, indicating a higher bioavailability. Also, the peak serum levels were higher and were reached earlier when given as a solution. Considerable individual variation of the maximum serum levels and the area under the curve values was observed for both methods of administration, but the time required to reach the maximum serum level was more predictable after administration of the solution.