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]

Source

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.

Abstract

BACKGROUND AND OBJECTIVE:

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.

METHODS:

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.

RESULTS:

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).

CONCLUSIONS:

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.