The accurate evaluation of a patient's medical history, particularly regarding recent pharmacological interventions, is critical in identifying the etiology of acute clinical deteriorations. You are evaluating five patients presenting with acute, severe complications. Match each patient's clinical profile with the specific targeted historical inquiry (offending agent) that must be identified to establish the mechanism of their acute deterioration.
- A 68-year-old man with Parkinson disease managed with levodopa-carbidopa and selegiline presents with a fever of 39.2°C (102.6°F), severe agitation, diaphoresis, and lower extremity hyperreflexia. He recently self-treated an upper respiratory illness.Recent ingestion of over-the-counter dextromethorphan
- A 54-year-old woman with bipolar disorder, stably maintained on lithium, presents with acute ataxia, slurred speech, severe nausea, and a new-onset coarse tremor. She recently visited an urgent care clinic for mild lower extremity edema and elevated blood pressure.Recent initiation of hydrochlorothiazide
- A 42-year-old man enrolled in a methadone maintenance program presents with profound somnolence, miosis, and a respiratory rate of 8 breaths/minute. He recently started systemic therapy for recalcitrant dermatophyte onychomycosis.Recent initiation of oral itraconazole
- A 75-year-old man with an estimated glomerular filtration rate of 22 mL/min/1.73 m² develops unresponsiveness, diffuse myoclonus, and nonconvulsive status epilepticus on day 3 of empiric treatment for hospital-acquired pneumonia.Administration of unadjusted intravenous cefepime
- A 30-year-old woman treated with citalopram for major depressive disorder presents with recurrent syncope. Electrocardiography reveals a QTc interval of 580 ms. She recently received an outpatient prescription for community-acquired pneumonia.Recent prescription of oral clarithromycin
Answer
Patient 1 matches with dextromethorphan (serotonin syndrome). Patient 2 matches with hydrochlorothiazide (lithium toxicity). Patient 3 matches with itraconazole (methadone accumulation). Patient 4 matches with unadjusted cefepime (neurotoxicity). Patient 5 matches with clarithromycin (QT prolongation).
Accurate medical history evaluation requires recognizing that each acute presentation described is the direct result of an iatrogenic pharmacological interaction or incorrect dosing. Patient 1 exhibits serotonin syndrome due to the combination of an MAOI and dextromethorphan. Patient 2 shows lithium toxicity precipitated by thiazide-induced proximal tubular sodium reabsorption. Patient 3 has opioid toxicity from CYP3A4 inhibition by itraconazole. Patient 4 developed cefepime-induced neurotoxicity due to failed renal dose adjustment. Patient 5 experienced Torsades de pointes due to synergistic QT prolongation and CYP inhibition by a macrolide antibiotic.
Step-by-Step Solution
Key Concept
Identification of critical drug-drug and drug-disease interactions through targeted medical history evaluation.