PITTSBURGH (AP) — Mylan Inc. said today that it started shipping its version of GlaxoSmithKline’s herpes drug Valtrex after winning approval from the Food and Drug Administration.

Mylan is shipping generic versions of Valtrex, or valacyclovir, in 500 milligram and 1000 milligram strengths. Sales of the drug totaled $2.15 billion in sales for the 12 months ended March 31, Mylan said.

Companies including Dr. Reddy’s Laboratories, Sandoz, and Teva Pharmaceutical Industries are also making generic versions of the drug.