Autonomic Pharmacology USMLE Step 1 Practice Question

A 61-year-old woman with a 12-year history of Sjogren syndrome presents to her rheumatologist reporting severe dry mouth, difficulty swallowing crackers and dry foods, and persistent eye irritation despite drinking water frequently throughout the day. She notes her symptoms have progressively worsened over the past six months. Vital signs are within normal limits, with a blood pressure of 126/78 mmHg and heart rate of 72 bpm. Examination reveals dry, sticky oral mucosa with reduced salivary pooling under the tongue, decreased tear meniscus on slit-lamp examination, and bilateral parotid gland enlargement. Anti-SSA and anti-SSB antibodies are positive. She has no history of asthma, chronic obstructive pulmonary disease, peptic ulcer disease, or iritis. Which of the following drugs would most directly improve her symptoms?