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Voiding & Outlet Pharmacotherapy

Pharmacotherapy targeting bladder outlet relaxation, voiding-phase contraction, and outlet tone — the medical companion to surgical management of BPH/LUTS, stress incontinence, underactive bladder, and detrusor-sphincter dyssynergia. Most agents act at three loci: the bladder neck and prostatic smooth muscle (α₁ receptors), the detrusor (cholinergic receptors), and the external sphincter and pelvic floor (skeletal muscle).

For OAB / storage-phase therapy see Storage & OAB. For pelvic-floor hypertonicity in the context of neuropathic pelvic pain see Neuropathic & Pelvic Pain.

  • α-BlockersTamsulosin, silodosin, alfuzosin, doxazosin, terazosin. BPH/LUTS first-line; medical expulsive therapy for distal ureteral stones > 5 mm; trial without catheter (TWOC) after AUR; CP/CPPS adjunct; intraoperative floppy iris syndrome (IFIS) and orthostatic hypotension as the dominant safety signals.
  • 5α-Reductase InhibitorsFinasteride and dutasteride. BPH with demonstrable prostate enlargement; MTOPS combination with α-blocker; adjusted PSA interpretation; the PCPT / REDUCE high-grade-cancer detection-bias controversy; cosmetic indications (hair loss).
  • α-AgonistsMidodrine, pseudoephedrine, phenylephrine. Limited off-label SUI evidence; specialist recurrent-priapism prevention; orthostatic hypotension in autonomic dysfunction; phenylephrine as the standard intracavernosal rescue for ischemic priapism.
  • Cholinergic AgonistsBethanechol as the canonical agent. Underactive bladder / detrusor underactivity — limited efficacy data, largely legacy. No established routine benefit; reliable bladder emptying remains central. Contraindicated in mechanical outlet obstruction.
  • Skeletal Muscle RelaxantsCyclobenzaprine, baclofen, tizanidine, methocarbamol. Selected pelvic-floor hypertonicity or dyssynergia adjuncts; limited evidence and agent-specific sedation/withdrawal risks.
  • DantroleneDirect skeletal-muscle relaxant for refractory dyssynergia — historical role. Hepatotoxicity limits modern use; largely supplanted by botulinum toxin to the external sphincter.