Etretinate pharmacokinetics in chronic renal failure. A preliminary study in psoriasis patients

Chronic renal failure (CRF) interferes with the catabolism of retinol and is frequently associated with hypervitaminosis A. The effect of CRF on the plasma levels of etretinate (Tigason, Tegison), an aromatic retinoid, was therefore studied in 4 patients who were given the drug as part of a maintenance antipsoriatic regimen. The concentrations of the parent compound and its main metabolites (etretin and isoetretin) were monitored for 24 h after receiving a routine dose of the drug. In comparison with 4 non-CRF patients receiving similar maintenance doses of etretinate, although the CRF patients had higher peak levels of the parent compound (p less than 0.01), the levels of the metabolites were similar or lower. The plasma half-lives for all compounds were approximately the same in each group, indicating that the catabolism of the drug was not affected by CRF. However, elevated etretinate concentrations may increase the drug accumulation in fat tissues and thereby prolong the time required for final elimination of the drug.