Pharmacodynamic interaction mechanismsDownloads

A 50-year-old woman presents with acute onset fever and chills for the past hour. She mentions earlier in the day she felt blue, so she took some St. John’s wort because she was told by a friend that it helps with depression. Past medical history is significant for hypertension, diabetes mellitus, and depression managed medically with captopril, metformin, and fluoxetine. She has no history of allergies. Her pulse is 130/min, the respiratory rate is 18/min, the blood pressure is 176/92 mm Hg, and the temperature is 38.5°C (101.3°F). On physical examination, the patient is profusely diaphoretic and extremely irritable when asked questions. Oriented x 3. The abdomen is soft and nontender with no hepatosplenomegaly. Increased bowel sounds are heard in the abdomen. Deep tendon reflexes are 3+ bilaterally and clonus is elicited. The sensation is decreased in the feet bilaterally. Mydriasis is present. Fingerstick glucose is 140 mg/dL. An ECG shows sinus tachycardia but is otherwise normal. Which of the following is the most likely cause of this patient’s condition?

A 59-year-old man is brought to the emergency department one hour after developing shortness of breath and “squeezing” chest pain that began while he was mowing the lawn. He has asthma, hypertension, and erectile dysfunction. Current medications include salmeterol, amlodipine, lisinopril, and vardenafil. His pulse is 110/min and blood pressure is 122/70 mm Hg. Physical examination shows diaphoresis. An ECG shows sinus tachycardia. Sublingual nitroglycerin is administered. Five minutes later, his pulse is 137/min and his blood pressure is 78/40 mm Hg. Which of the following is the most likely mechanism of this patient's hypotension?