Effects of health literacy and polypharmacy on medication adherence.

Objective: To determine if health literacy has an effect on medication adherence in patients taking fewer than five prescriptions (no polypharmacy), and those taking five or more prescriptions (polypharmacy).

Design: Retrospective cohort.

Setting: The Primary Care Residents' Clinic at Virginia Commonwealth University Health System (VCUHS).

A potential interaction between warfarin and atovaquone.

Objective: To report a case of increased international normalized ratio (INR) in a patient established on warfarin therapy who was then initiated on atovaquone therapy.

Case Summary: A 53-year-old African American male with HIV was prescribed warfarin 5 mg/day for 12 months after diagnosis of idiopathic deep vein thrombosis and bilateral pulmonary emboli (target INR 2.5 [range 2.