Drug Interactions: Macrolide Antibiotics and Beta-Blockers; CYP3A4 Inhibition; Hyperkalemia in Renal Failure

A 58-year-old man with hypertension and chronic heart failure is on lisinopril, metoprolol, and furosemide. He develops a respiratory tract infection and is started on clarithromycin for 7 days. On day 3 of antibiotic therapy, he presents with severe hypotension (BP 88/52 mmHg), bradycardia (HR 42/min), and worsening dyspnea. His serum potassium is 6.8 mEq/L and creatinine has risen from 1.2 to 2.1 mg/dL. Which of the following best explains the acute clinical deterioration?