Dutasteride/tamsulosin fixed-dose combination for the treatment of benign prostatic enlargement

Fixed-dose dutasteride/tamsulosin is a combination therapy for lower urinary tract symptoms secondary to benign prostatic enlargement (LUTS/BPE), which is composed of two active ingredients, tamsulosin and dutasteride. Tamsulosin is an α-adrenoceptor blocker that is relatively selective for the α(1A)-adrenoceptor subtype within the prostatic smooth muscles. The inhibition of α(1A)-adrenoceptors results in smooth muscle relaxation. Dutasteride is an inhibitor of 5α-reductase, an enzyme that is responsible for the conversion of testosterone to its active form dihydrotestosterone. This occurs in the prostate, liver and skin. 5α-Reductase results in the shrinkage of the prostatic epithelium and reduction in the size of the prostate. No clinical studies have been performed on the fixed-dose dutasteride/tamsulosin combination, although several clinical trials have been conducted on the combination therapy of 5α-reductase and α-adrenoceptor blockers for LUTS/BPE. The CombAT study is a multicenter, randomized, double-blind trial in men with a clinical diagnosis of LUTS/BPE that is comparing tamsulosin or dutasteride as a monotherapy to tamsulosin and dutasteride as combination therapy (as separate tablets). The combination therapy was associated with significant improvements in the symptom score compared to tamsulosin or dutasteride as monotherapy. It is therefore logical to combine the two medications into one tablet.