A 58-year-old man with gout presents with 4 days of fever and a progressively worsening rash. Eight weeks ago, he started a new medication for gout prophylaxis. He now reports malaise and pruritus. Physical examination shows diffuse erythematous maculopapular (morbilliform) eruption that began on the face and upper trunk and has spread to the extremities. There is prominent facial edema and tender cervical and axillary lymphadenopathy. Laboratory studies show: WBC 15,800/µL with eosinophils 14%, AST 165 U/L, ALT 190 U/L, and creatinine 1.9 mg/dL (baseline 1.0). Which of the following is the most likely diagnosis?