Q. A 35-year-old woman presents to your primary care clinic with complaints of recurrent episodes of her fingers turning white, followed by blue discoloration, and then redness and throbbing pain when exposed to cold temperatures or during periods of stress. She reports that these episodes are painful and interfere with her daily activities. The patient has no significant medical history. Her temperature is 98.6°F (37°C), pulse is 80 beats per minute, blood pressure is 120/80 mmHg and respiratory rate is 14 per minute. Physical examination is unremarkable. What is the drug of choice to treat her condition?