tamsulosin
Summary
Tamsulosin is a selective α1A-adrenergic receptor antagonist primarily used to treat benign prostatic hyperplasia (BPH) by relaxing smooth muscle in the prostate and bladder neck. It improves urinary flow and reduces BPH symptoms with minimal cardiovascular side effects due to its selectivity.
Detail
Tamsulosin is a highly selective α1A-adrenergic receptor antagonist that preferentially blocks α1A receptors found in prostatic smooth muscle, bladder neck, and urethra. This selectivity results in smooth muscle relaxation and improved urinary flow without significant effects on vascular α1B receptors, minimizing orthostatic hypotension compared to non-selective α1 blockers. The drug is metabolized primarily by CYP2D6 and CYP3A4 enzymes. Common side effects include retrograde ejaculation (8-18% of patients), dizziness, and rhinitis. Tamsulosin can cause intraoperative floppy iris syndrome (IFIS) during cataract surgery due to iris dilator muscle α1A receptor blockade, requiring preoperative ophthalmologic consultation. It's contraindicated with strong CYP3A4 inhibitors and should be used cautiously in patients with severe hepatic impairment. The drug provides symptomatic relief but doesn't reduce prostate size or prevent BPH progression.
Sources
- Goodman & Gilman's The Pharmacological Basis of Therapeutics
- Katzung's Basic & Clinical Pharmacology
- Campbell-Walsh Urology
- First Aid for the USMLE Step 1
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.