Q. An 18-year-old girl is referred to your clinic with recurrent pain and color change in the fingers of both hands. The problem started six months ago, and since then, the pain and color change happen whenever she is in cold weather. Recently, stress and anxiety also triggered the attacks. She always has to wear gloves because even the air condition breeze in the summer causes the attacks. She mentions every attack, all the fingers become painful and turn white, then after a while, the finger becomes blue, and at the end, they turn red, warm, and edematous. She has no history of disease and takes no medication, tobacco, alcohol, or illicit drugs. She is a freshman at college and studies literature. She reports no regular contact with chemicals. Her elder sister has the same problem. On physical examination, she is a thin girl with a body mass index of 17.3 kg/m2. Temperature is 37.6 degrees Celsius (99.68 degrees Fahrenheit), pulse rate is 81/min, respiratory rate is 14/min, and blood pressure is 97/65 mmHg. Now the fingers are typically pink, and there are no ulcerations. The toes, ears, and nose are normal. The rest of the physical exam is unremarkable and normal. The lab tests you ordered (CBC, complete metabolic panel, ANA, TSH, ESR, CRP, and urinalysis) returned normal. Since the gloves and hand warmers were ineffective, you decided to treat her with medications. What medication will be the best choice for her?