From CBC News:
Prescription drug shipments to be tagged electronically
Three large drug manufacturers in the United States say they plan to add radio transmitter tags to bottles of pills to prevent counterfeiting and theft.

The transmitters will be used on larger bottles sent from factories to pharmacies, not on the containers bought by consumers.

Purdue Pharma announced it will begin electronic tracking of shipments of OxyContin, a narcotic painkiller, to Wal-Mart and wholesaler H.D. Smith.