Oxybutynin manages overactive bladder by which action?

• A. Increasing detrusor activity
• B. Relaxing urethral sphincter
• C. Reducing bladder contractions
• D. Increasing urine production

Answer: (C)

Oxybutynin helps overactive bladder by dampening the signals that cause the bladder to contract. It’s an antimuscarinic medication that blocks acetylcholine at muscarinic receptors on the detrusor muscle, mainly the M3 receptors. By reducing those parasympathetic-driven contractions during the filling phase, the detrusor relaxes, the bladder can hold more urine, and urgency, frequency, and urge incontinence are decreased. This is opposite of increasing detrusor activity, and it doesn’t work by relaxing the urethral sphincter or by increasing urine production. Side effects come from the same anticholinergic action, such as dry mouth or blurred vision.