Tamsulosin is a selective α1 receptor antagonist that has preferential selectivity for the α1A receptor in the prostate versus the α1B receptor in the blood vessels. When alpha 1 receptors in the bladder neck, prostate, ureter, and urethra are blocked, a relaxation in smooth muscle tissue results. Tamsulosin is primarily used for benign prostatic hyperplasia (BPH) and to help with the passage of kidney stones (The evidence for benefit with a kidney stone is appears to be effective only for stones over 4 mm and less than 10 mm in size).Tamsulosin is also used as an add-on treatment for acute urinary retention. Dutasteride belongs to a class of drugs called 5α-reductase inhibitors, which block the action of the 5α-reductase enzymes that convert testosterone into dihydrotestosterone (DHT) which primarily responsible for the initial development and enlargement of prostate gland. It inhibits all three forms of 5α-reductase, and can decrease DHT levels in the blood by up to 98%. The combination of Tamsulosin and Dutasteride provides greater symptom benefits compared to monotherapy with either agent alone for treatment of benign prostatic hyperplasia. This combination can be useful because it may take up to six months for symptomatic relief to be found when using 5-alpha-reductase inhibitors such as dutasteride compared to alpha-1 receptor blockers, which can provide relief in some cases within 48 hours.