विवरण
Combining tamsulosin (alpha-1 blocker) with sildenafil (PDE-5 inhibitor) produces additive vasodilation, substantially increasing the risk of symptomatic hypotension, dizziness, and syncope.
तंत्र
Tamsulosin reduces peripheral vascular resistance via alpha-1 adrenoceptor blockade; sildenafil inhibits PDE-5 in smooth muscle, increasing cGMP-mediated vasodilation. The pharmacodynamic combination causes additive blood pressure reduction, particularly during standing.
नैदानिक महत्व
Multiple controlled studies document clinically significant blood pressure reductions with this combination; the interaction is particularly pronounced with the first sildenafil dose or with dose increases.
प्रबंधन
Warn patients about orthostatic hypotension; instruct patient to take sildenafil at the lowest effective dose and avoid taking it when haemodynamically unstable; monitor blood pressure; consider timing doses to reduce peak overlap.