RT Journal Article SR Electronic T1 Disposition of [14C]acitretin in humans following oral administration. JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 211 OP 215 VO 22 IS 2 A1 F Rubio A1 B K Jensen A1 L Henderson A1 W A Garland A1 A Szuna A1 C Town YR 1994 UL http://dmd.aspetjournals.org/content/22/2/211.abstract AB The disposition of the antipsoriatic agent, acitretin, was investigated in six healthy human volunteers who each received a single, oral 50 mg dose of [14C]acitretin (50 microCi). plasma, urine, and feces were collected for 240 hr after administration. Mean values of 20.9 and 62.6% of the administered dose were recovered in the urine and feces, respectively. The terminal elimination half-life of total radioactivity from the plasma was approximately 120 hr. Extraction of pooled plasma samples followed by separation by HPLC and quantitation by liquid scintillation counting indicated that acitretin and its 13-cis-isomer, isoacitretin, were minor fractions of the total drug-related material in the plasma at most time points up to 72-hr postdose. The structures of acitretin, isoacitretin, and two other metabolites--(5E,7E)-8-(4-methoxy,2,3,6-trimethylphenyl)-2,6 -dimethyl-5,7- octadienoic acid (I) and (5E,7E)-8-(4-hydroxy-2,3,6-trimethylphenyl)-2,6-dimethyl-5,7 -octadienoic acid (II)--were confirmed by MS and cochromatography with authentic standards. I and II were major fractions of the drug-related material in the plasma at all time points. Other compounds, whose structures could not be confirmed, also account for a significant fraction of the circulating radioactivity.