From the Telegraph (UK):
Pfizer admits limiting drugs supplies to UK
Pfizer, the US drug giant, has told UK wholesalers that it will only supply enough prescription medicines to meet domestic demand in what is believed to be an attempt to stop the reimport of drugs into the United States.

A number of drug companies, including Pfizer, have put similar caps on supply in Canada, where drugs are cheaper than in the US and there is a growing business in Canadian drugs being sold to US residents. However, it is believed to be the first to cap supplies in Britain.