Pharmacology · patient case question
All of the following medications reduce salivary flow EXCEPT:
Patient case: The mouth that will not stay wet
demo: 54-year-old female
chief: Burning, sticky mouth for the past eight months; food gets caught and she wakes at night to sip water.
history: Hashimoto thyroiditis. Her rheumatologist ordered an autoantibody panel after she reported gritty, burning eyes.
meds: Levothyroxine 75 mcg daily. Amitriptyline 25 mcg at night for chronic tension headache.
findings: Anti-SSA (Ro) strongly positive. Salivary pooling is absent; the mucosa is dry and the tongue is fissured with papillary atrophy. Cracking and erythema at both commissures. Two new cervical lesions since her last visit a year ago.
Show answer and explanation
Correct answer: B. Pilocarpine
- A. IS a cause. Diphenhydramine is a first-generation antihistamine with substantial anticholinergic action, producing dry mouth and sedation.
- B. CORRECT — this is the EXCEPTION. PILOCARPINE is a muscarinic AGONIST (a cholinergic drug) that INCREASES salivary secretion. It is prescribed precisely TO TREAT xerostomia, particularly in Sjögren syndrome and after head and neck radiotherapy. Cevimeline works the same way with somewhat greater M3 selectivity.
- C. IS a cause. Amitriptyline is a tricyclic antidepressant with powerful anticholinergic activity, and dry mouth is among its most common adverse effects.
- D. IS a cause. Scopolamine is a classic ANTImuscarinic agent, used for motion sickness and to reduce secretions — xerostomia is its expected effect.
Note: Pattern to hold onto: ANTI-cholinergic (antimuscarinic) drugs dry the mouth; CHOLINERGIC agonists such as pilocarpine and cevimeline wet it. Side effects of pilocarpine include sweating, flushing and GI upset; it is contraindicated in uncontrolled asthma and narrow-angle glaucoma.