Pharmacokinetic interaction mechanisms — MCQs

A 61-year-old male is given acetazolamide to treat open-angle glaucoma. Upon diuresis, his urine is found to be highly alkaline. Which of the following accounts for the alkaline nature of this patient’s urine?

A 72-year-old man presents to the emergency department with a 1 hour history of bruising and bleeding. He says that he fell and scraped his knee on the ground. Since then, he has been unable to stop the bleeding and has developed extensive bruising around the area. He has a history of gastroesophageal reflux disease, hypertension, and atrial fibrillation for which he is taking an oral medication. He says that he recently started taking omeprazole for reflux. Which of the following processes is most likely inhibited in this patient?

A 72-year-old woman presents to the clinic complaining of diarrhea for the past week. She mentions intense fatigue and intermittent, cramping abdominal pain. She has not noticed any blood in her stool. She recalls an episode of pneumonia last month for which she was hospitalized and treated with antibiotics. She has traveled recently to Florida to visit her family and friends. Her past medical history is significant for hypertension, peptic ulcer disease, and hypercholesterolemia for which she takes losartan, esomeprazole, and atorvastatin. She also has osteoporosis, for which she takes calcium and vitamin D and occasional constipation for which she takes an over the counter laxative as needed. Physical examination shows lower abdominal tenderness but is otherwise insignificant. Blood pressure is 110/70 mm Hg, pulse is 80/min, and respiratory rate is 18/min. Stool testing is performed and reveals the presence of anaerobic, gram-positive bacilli. Which of the following increased this patient’s risk of developing this clinical presentation?

A 76-year-old man comes to the physician for a follow-up examination. One week ago, he was prescribed azithromycin for acute bacterial sinusitis. He has a history of atrial fibrillation treated with warfarin and metoprolol. Physical examination shows no abnormalities. Compared to one month ago, laboratory studies show a mild increase in INR. Which of the following best explains this patient's laboratory finding?

A group of researchers wish to develop a clinical trial assessing the efficacy of a specific medication on the urinary excretion of amphetamines in intoxicated patients. They recruit 50 patients for the treatment arm and 50 patients for the control arm of the study. Demographics are fairly balanced between the two groups. The primary end points include (1) time to recovery of mental status, (2) baseline heart rate, (3) urinary pH, and (4) specific gravity. Which medication should they use in order to achieve a statistically significant result positively favoring the intervention?

A 55-year-old male presents to his primary care physician for a normal check-up. He has a history of atrial fibrillation for which he takes metoprolol and warfarin. During his last check-up, his international normalized ratio (INR) was 2.5. He reports that he recently traveled to Mexico for a business trip where he developed a painful red rash on his leg. He was subsequently prescribed an unknown medication by a local physician. The rash resolved after a few days and he currently feels well. His temperature is 98.6°F (37°C), blood pressure is 130/80 mmHg, pulse is 95/min, and respirations are 18/min. Laboratory analysis reveals that his current INR is 4.5. Which of the following is the most likely medication this patient took while in Mexico?

A 29-year-old woman presents with shortness of breath and chest pain for the past week. She says her chest pain is aggravated by deep breathing and she becomes short of breath while walking upstairs in her home. She also has been feeling feverish and fatigued for the past week, as well as pain in her wrists, hands, and left knee. Review of systems is significant for a 4.5 kg (10.0 lb) weight loss over the previous month. Past medical history consists of 2 spontaneous abortions, both of which occurred in the 1st trimester. On physical examination, there is a pink rash present over her face, which is aggravated by exposure to sunlight. There are decreased breath sounds on the right. A chest radiograph is performed which reveals evidence of a right pleural effusion. Serum ANA and anti-dsDNA autoantibodies are positive. Urinalysis is unremarkable. Errors with which of the following is most likely to lead to her disease?

A 66-year-old man was referred for endoscopic evaluation due to iron deficiency anemia. He has had anorexia and weight loss for two months. Three years ago, the patient had coronary artery bypass grafting and aortic mechanical valve replacement. He has a 12-year history of diabetes mellitus and hypertension. He takes warfarin, lisinopril, amlodipine, metformin, aspirin, and carvedilol. His blood pressure is 115/65 mm Hg, pulse is 68/min, respirations are 14/min, temperature is 36.8°C (98.2°F), and blood glucose is 220 mg/dL. Conjunctivae are pale. Heart examination reveals a metallic click just before the carotid pulse. Which of the following is the most appropriate switch in this patient’s drug therapy before the endoscopy?

A 17-year-old woman is rushed into the emergency department by her father who found her collapsed in her bedroom 15 minutes before the ambulance's arrival. There was an empty bottle of clomipramine in her bedroom which her mother takes for her depression. Vital signs include the following: respiratory rate 8/min, pulse 130/min, and blood pressure 100/60 mm Hg. On physical examination, the patient is unresponsive to vocal and tactile stimuli. Oral mucosa and tongue are dry, and the bladder is palpable. A bedside electrocardiogram (ECG) shows widening of the QRS complexes. Which of the following would be the best course of treatment in this patient?

A 45-year-old woman presents to the emergency department with fever, cough, tonsillar enlargement, and bleeding lips. She has a diffuse blistering rash that encompasses the palms and soles of her feet, in total covering 55% of her total body surface area (TBSA). The upper epidermal layer easily slips away with slight rubbing. Within 24 hours the rash progresses to 88% TBSA involvement and the patient requires mechanical ventilation for respiratory distress. Which of the following is the most likely etiology of this patient’s condition?