A 33-year-old man with advanced Crohn disease is treated with multiagent therapy including 6-mercaptopurine. On his most recent CT scan, there is evidence of disease progression to include the entire ileum and right colon. What is the most likely explanation for these findings?

A 33-year-old man with advanced Crohn disease is treated with multiagent therapy including 6-mercaptopurine. On his most recent CT scan, there is evidence of disease progression to include the entire ileum and right colon. What is the most likely explanation for these findings?

A 23-year-old man with erectile dysfunction refuses to see a physician for his problem. Instead, he purchases an over-the-counter product that contains yohimbine. He claims that he now has improved sexual function with improved quality of his erections. What is the most likely explanation for this finding?

A 23-year-old woman presents to the emergency department with a headache. Her headaches began on the right frontal side and radiated to the back of the right side of her head. She has vomited twice. She has photophobia and phonophobia. She usually takes sumatriptan as her headache begins, but she has none left. What is the mechanism of action of sumatriptan?

A 21-year-old woman presents to the emergency department (ED) after she intentionally took 20 alprazolam 15 min ago in a suicide attempt. She has never been on benzodiazepines before in the past. The ED physician wants to reverse the effects of the alprazolam immediately. What is the most appropriate treatment?

A 37-year-old man complains of chest pain after meals. He says this pain has gone on for a few months, and he gets only minimal relief from antacid tablets. The physician prescribes a drug that will decrease the amount of acid secreted by blocking a histamine receptor. Which of the following drugs works by this mechanism?