In Vivo Investigation in Pigs of Intestinal Absorption, Hepatobiliary Disposition, and Metabolism of the 5α-Reductase Inhibitor Finasteride and the Effects of Coadministered Ketoconazole

This study investigated the pharmacokinetics and metabolism of finasteride, a 5α-reductase inhibitor used to treat benign prostatic hyperplasia and male pattern baldness, in pigs. The study found that ketoconazole increased the bioavailability of finasteride and the terminal half-life. The liver extraction ratio was time-dependent and varied with the two routes of administration. After intrajejunal administration, the liver extraction ratio was significantly reduced by ketoconazole treatment. The study provides valuable insights into the pharmacokinetics of finasteride and its interactions with other drugs.