Urinary retention is the inability to empty the bladder completely, often due to outflow obstruction. In older men, the most common cause is benign prostatic hyperplasia (BPH) — enlargement of the prostate leading to mechanical and functional obstruction of the bladder outlet. Adobe stock Fig 2: Benign prostatic hyperplasia (BPH). Comparison between normal prostate and enlarged prostate. Pathophysiology Two major components contribute to obstruction in BPH: Static component: Enlarged prostate compresses the urethra. Dynamic component: Increased alpha1-adrenoceptor–mediated tone in the prostate and bladder neck. Pharmacological Management The primary pharmacological classes for managing urinary retention and BPH are: 1. Alpha1-Adrenoceptor Blockers Examples: Tamsulosin, Alfuzosin, Doxazosin, Terazosin 2. 5α-Reductase Inhibitors Examples: Finasteride, Dutasteride 3. Phosphodiesterase Type 5 (PDE5) Inhibitors Example: Tadalafil may be considered when erectile dysfunction coexists. Rate This Article