Benztropine mesylate is used as adjunct pharmacotherapy to manage motor effects of Parkinson's disease. What class does it belong to?

• A. Dopamine receptor agonist
• B. MAO-B inhibitor
• C. COMT inhibitor
• D. Anticholinergic

Answer: (D)

Benztropine mesylate is an anticholinergic, specifically a central muscarinic receptor antagonist. In Parkinson disease, dopamine loss creates relatively excessive cholinergic activity in the striatum. By blocking acetylcholine receptors, benztropine reduces this cholinergic overactivity, helping to lessen tremor and rigidity and to augment the effect of dopaminergic therapy. It’s used as an adjunct to improve motor symptoms rather than to increase dopamine directly. The other drug classes listed work differently: dopamine receptor agonists mimic dopamine signaling, MAO-B inhibitors slow dopamine breakdown, and COMT inhibitors prevent levodopa degradation. Anticholinergics don’t boost dopamine; they rebalance the system by dampening cholinergic activity. Side effects stem from anticholinergic action (dry mouth, constipation, blurred vision, cognitive changes), which is why these are used with caution, especially in older patients.