When Pfizer took direct control of distribution of its medicines across the UK last spring, it soon noticed curious patterns in orders for Genotropin, a growth hormone for children.

One pharmacy requested 300 packets at a time, although the drug is so rarely used it was unlikely it would have had more than a single prescription to fulfil each month in the community it served. The pharmacist was ordering large quantities of the drug to resell to other pharmacists at a higher price.