A Population Pharmacokinetic Model for Individualized Regimens of Finasteride According to CYP3A5 Genotype and Liver Function

This study developed a population pharmacokinetic model to tailor finasteride dosages based on CYP3A5 genotype and liver function, using data from healthy Korean males. It found that individuals with the homozygous CYP3A5*3/*3 genotype had approximately 34% lower clearance of finasteride compared to those with the *1 allele, and higher alanine transaminase (ALT) levels were associated with decreased clearance. The model indicated that the mean finasteride concentration at steady state was 1.59–1.83 times higher in individuals with the *3/*3 genotype and ALT levels above 40 IU/L. These findings suggest that finasteride dosages should be adjusted based on CYP3A5 genotype and liver function to avoid adverse side effects, aiding in its clinical application.