Gain access to the Patient Portal to see information on your prescriptions, ... Loudoun Internal Medicine Associates, part of the Loudoun Medical Group family. Social Media. Lansdowne. 44055 Riverside Parkway Suite 116 Leesburg, VA 20176. Ph: 703.858.3220 . Purcellville. 921 E Main Street Suite 2D Purcellville, VA 20132. Ph: 703.858.3204..