Flomax; Harnal; Pradif|Tamsulosin is an 1-adrenergic receptor antagonist that is clinically used to treat benign prostatic hyperplasia (BPH). Tamsulosin inhibits peristaltic activity, increases bladder blood flow, and decreases bladder overactivity.|C20H28N2O5S HCl|444.98||+4°C|Slightly soluble in water to 10 mM. Weakly soluble in methanol. DMSO to 100 mM.