Question

A $54$-year-old man comes to the emergency department due to a $3$-day history of high fevers, chills, drenching sweats, and extreme fatigue. He resides in coastal Massachusetts and frequently hikes in wooded areas. His past medical history is notable for hereditary spherocytosis, for which he underwent a splenectomy at age $20$. His temperature is $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), blood pressure is $110/70\text{ mmHg}$, pulse is $115/\text{min}$, and respirations are $18/\text{min}$. Physical examination reveals scleral icterus and pale conjunctivae. There is no rash or lymphadenopathy. Laboratory studies show:

- Hemoglobin: $8.2\text{ g/dL}$
- Platelet count: $95,000/\text{mm}^3$
- Leukocyte count: $9,400/\text{mm}^3$
- Total bilirubin: $4.1\text{ mg/dL}$ (direct: $0.6\text{ mg/dL}$)
- Lactate dehydrogenase: $850\text{ U/L}$

A peripheral blood smear demonstrates intraerythrocytic pleomorphic ring forms and occasional tetrad structures. Which of the following is the most appropriate pharmacotherapy for this patient's condition?