A 55-year-old man with long-standing hypertension and ischemic cardiomyopathy presents to your clinic with exertional dyspnea and palpitations. He has persistent atrial fibrillation. Current medications include carvedilol, lisinopril, spironolactone, and furosemide. Due to continued symptoms and inadequate rate control, digoxin is added.  What is the primary therapeutic role of digoxin in this clinical context? 

After 5 years on levodopa, a patient develops involuntary writhing movements. This is most likely: 

A 52-year-old man with severe alcohol use disorder is interested in medication-assisted treatment after completing inpatient detoxification. He has normal renal function. He expresses strong motivation to remain abstinent but admits that cravings are high when he is around friends who drink. He wants “something that will stop me from drinking if I slip.” Which pharmacologic agent is most appropriate for this treatment goal? 

Which toxicity can occur with prolonged nitroprusside infusion? 

A 29-year-old man with a history of intravenous heroin use is brought to the ED unresponsive with shallow respirations (RR 6/min) and pinpoint pupils. He receives IV naloxone 0.4 mg, and within minutes he becomes alert but develops severe agitation, diaphoresis, piloerection, tachycardia, hypertension, and nausea. Which best explains this clinical presentation? 

A 55-year-old on quinidine develops QT prolongation and torsades de pointes. Which electrolyte abnormality likely contributed? 

A patient on levodopa reports “wearing off” between doses. Which adjustment is appropriate? 

A patient with treatment-resistant schizophrenia is started on clozapine. What is the most important baseline test? 

A patient on chronic benzodiazepine therapy suddenly discontinues the drug. What is the most concerning complication? 

Which neurotransmitter system is central to reward and reinforcement in addiction?