Q. A 60-year-old woman presents to the medical outpatient department with a painful, blistering rash on her left flank that developed over the past three days. She reports that the pain began as a tingling sensation a few days before the rash appeared. Her medical history is significant for hypertension and type 2 diabetes mellitus. She has not received the herpes zoster vaccine. On physical examination, there is a unilateral, vesicular rash in a dermatomal distribution along the T6 dermatome. There are no signs of secondary infection. Patient is vitally stable with unremarkable systemic examination. What is the most appropriate initial treatment?