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Library / Pharmacology / Autonomics / Anticholinergics / Oxybutynin & Tolterodine

Oxybutynin & Tolterodine

Key Board Facts Grid

Target Receptors

M3 antagonist in detrusor muscle

BBB Penetration

Oxybutynin crosses BBB more than tolterodine; both have CNS effects

Primary Indication

Urge incontinence, overactive bladder

First-Line Antidote

Physostigmine for severe anticholinergic toxicity; mirabegron as alternative class

Mechanism of Action

  • M3 antagonism in the bladder detrusor reduces involuntary contractions.
  • Increases bladder capacity and decreases urgency.
  • Oxybutynin is less M3-selective and has more anticholinergic side effects.
  • Tolterodine, darifenacin, solifenacin are more selective.

Adverse Effects & Toxicities

  • Dry mouth, constipation, urinary retention, blurred vision.
  • Cognitive impairment and delirium in elderly, especially oxybutynin.
  • Contraindications: narrow-angle glaucoma, severe BPH/urinary retention, GI obstruction.

DO / OMM Board Pearl

M3 blockade reduces S2–S4 parasympathetic bladder tone and unmasks T12–L2 hypogastric sympathetic influence. Mirabegron (β3 agonist) is a non-anticholinergic alternative.