Which class reduces bladder contractility and can cause retention?

• A. Analgesics
• B. Anticholinergics
• C. Diuretics
• D. Alpha blockers

Answer: (B)

Anticholinergics work by blocking acetylcholine at muscarinic receptors in the bladder. The detrusor muscle contracts when acetylcholine stimulates these receptors, so blocking this signal reduces detrusor contractility. When the bladder can’t contract effectively to push urine out, emptying is incomplete and retention can occur. This is why anticholinergic medications used for overactive bladder can cause urinary retention, especially in people with additional risk factors like enlarged prostate or age-related changes. Other drug classes don’t primarily reduce bladder contraction: analgesics can contribute to retention through different mechanisms (such as increased sphincter tone or CNS effects), diuretics increase urine production, and alpha blockers relax the bladder outlet rather than the detrusor muscle, often aiding voiding rather than causing retention.