Mechanism of action tamsulosin?

Question

Accepted Answer

Mechanism: Tamsulosin is a selective alpha-1 adrenergic receptor antagonist (competitive, reversible). It has high affinity for the alpha-1A subtype, with some activity on alpha-1D and relatively little on alpha-1B.
Site of action: smooth muscle in the prostate, bladder neck, and proximal urethra.
Effect: by blocking alpha-1A receptors, it reduces norepinephrine-induced contraction of prostatic and bladder neck smooth muscle. This relaxes these tissues, decreasing dynamic bladder outlet obstruction and improving urinary flow and BPH symptoms.
Key point: it does not shrink the prostate (not a 5-alpha-reductase inhibitor) but relieves symptoms by relaxing smooth muscle.
Practical note: due to its alpha-1A selectivity, it tends to cause less orthostatic hypotension than nonselective alpha blockers. Onset of symptom relief is often within days to weeks, with maximum effect over several weeks.

Ask Questions, Get Industry Insights … Instantly