Interaction Study Between Finasteride and Tamsulosin in Healthy Young Male Subjects
Kim KA, Park JY.Clin Drug Investig.2013 Jul 10. [Epub ahead of print]


Department of Clinical Pharmacology and Toxicology, Anam Hospital, Korea University College of Medicine, 126-1, Anam-dong 5-ga, Sungbuk-gu, Seoul, 136-705, Korea.



Finasteride, a 5α-reductase inhibitor, and tamsulosin, an α1-adrenoceptor antagonist, are used to improve the symptoms of benign prostatic hyperplasia. The concomitant use of finasteride and tamsulosin is frequent clinically and a fixed-dose combination drug is being developed. The objective of this study is to assess the possibility of a pharmacokinetic interaction between finasteride and tamsulosin in healthy male subjects.


This study was designed to investigate the pharmacokinetic interaction between finasteride and tamsulosin and was conducted as an open-label, randomized, three-treatment, three-period, crossover study of 30 healthy male subjects. Each subject received tamsulosin 0.2 mg alone, finasteride 5 mg alone, or the two in combination daily for 6 days. Plasma samples were collected and finasteride and tamsulosin concentrations were measured.


Coadministration of finasteride and tamsulosin did not alter the plasma concentration profiles or pharmacokinetic characteristics of either drug. The ratios of the log-transformed maximum plasma concentration (C max) and area under the concentration-time curve (AUC) of finasteride at steady state between finasteride alone and finasteride in combination with tamsulosin [point estimate (90 % CI)] were 0.941 (0.882-1.004) and 0.984 (0.934-1.037), and those of tamsulosin between tamsulosin alone and in combination with finasteride were 1.009 (1.002-1.207) and 1.028 (0.938-1.128), respectively (all P-values >0.05).


Coadministration of finasteride 5 mg once daily and tamsulosin 0.2 mg once daily did not affect the steady-state pharmacokinetics of finasteride and tamsulosin. Therefore, no dosage adjustment is necessary for the combination of these two drugs.