Pharmacology · single question
Which of the following drugs REDUCES salivary flow? (Select the EXCEPTION — which one does NOT reduce salivary flow?)
Show answer and explanation
Correct answer: D. Pilocarpine
Pilocarpine is a cholinergic (muscarinic) agonist — it STIMULATES salivary flow and is used to treat xerostomia in Sjogren's syndrome. All the others reduce salivary flow: anticholinergics (atropine, scopolamine), antihistamines, tricyclic antidepressants, antihypertensives, and diuretics all cause xerostomia as a side effect.
- A. CORRECT. Pilocarpine is a muscarinic agonist that INCREASES salivary secretion. It is the exception — it does NOT reduce salivary flow.
- B. Incorrect (it DOES reduce flow). Amitriptyline is a tricyclic antidepressant with strong anticholinergic side effects, causing significant xerostomia.
- C. Incorrect (it DOES reduce flow). Diphenhydramine (Benadryl) is an antihistamine with anticholinergic properties that reduces salivary secretion.
- D. Incorrect (it DOES reduce flow). Atropine is a classic anticholinergic that blocks muscarinic receptors, markedly reducing salivary production.