Following oral administration of acitretin with food, peak plasma concentrations of unchanged drug (Ro 10-1670) are reached within 4 h. The mean absolute bioavailabihty of acitretin is 59% with high interpatient variability consistent with that of etretinate. Taking acitretin with food results in an increased and more consistent bioavailabihty. The drug appears to be extensively distributed throughout the body without unexpected accumulation and the elimination half-life is approximately 50 h. Acitretin has a profound pharmacokinetic advantage over etretinate because it is eliminated more rapidly from the body; etretinate is sequestered into fatty tissue due to its greater lipophilicity creating a deep compartment from which it is only slowly released. Acitretin is eliminated entirely by the metabolism and the resultant metabolites are excreted via the kidney and bile.