Article date: May 1996
By: E. K. BENDRISS, Y. BECHTEL, A. BENDRISS, Ph. HUMBERT, G. PAINTAUD, J. MAGNETTE, P. AGACHE, P. R. BECHTEL, in Volume 41, Issue 5, pages 421-424
Eight patients with psoriasis were given 200 mg caffeine orally with or without 1.2 mg kg−1 of 5‐methoxypsoralen. Blood and urine samples were collected over a 2‐day period. During 5‐methoxypsoralen coadministration, the apparent volume of distribution of caffeine remained unchanged, but oral clearance (CLp.o.) decreased from 9.5±3.8 (mean±s.d.) to 3.2±0.5 l h−1 (P<0.01). The area under the plasma concentration‐time curve (AUC) increased from 24±9 to 73±29 mg l−1 h (P<0.001). This decrease in CLp.o. with increased AUC was consistent with a CYP1A2‐dependent inhibition of caffeine N‐demethylation which was further supported by significant decreases in the (AFMU+1U+1X)/17U and (AFMU+1U+1X)/17X urinary metabolic ratios.
DOI: 10.1046/j.1365-2125.1996.33311.x
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