Silodosin

Silodosin is a selective alpha-1A adrenergic receptor antagonist approved for the treatment of lower urinary tract symptoms due to benign prostatic hyperplasia (BPH) in men. By selectively blocking alpha-1A receptors in the prostate and bladder neck, it relaxes smooth muscle and improves urine flow, reducing obstructive symptoms.

The usual dose is 8 mg once daily taken with a meal. In patients with renal impairment or hepatic impairment, dose adjustments may be required, and silodosin is generally not recommended in severe hepatic impairment or severe renal impairment. Initiation should be cautious because of potential orthostatic effects, especially at the first dose.

Common adverse effects include retrograde ejaculation, dizziness, orthostatic hypotension, fatigue, and nasal congestion. Less frequent but notable risks include syncope and hypersensitivity reactions. Because of its effect on ejaculation, some men may notice changes in sexual function.

Contraindications include hypersensitivity to silodosin and severe hepatic impairment. Cautions include use in elderly patients, potential interactions with other antihypertensives or phosphodiesterase-5 inhibitors (which can increase the risk of hypotension), and possible increased exposure with strong inhibitors or inducers of drug-metabolizing enzymes. Silodosin may interact with drugs that affect hepatic enzymes and renal excretion.

Pharmacokinetically, silodosin is absorbed orally (peak levels within a few hours), with a half-life around 13 hours. It is extensively metabolized in the liver and primarily excreted in urine and feces. Brand names include Rapaflo, and it is available in generic form in some regions.