The government has reneged on its promise to put excess purchase profits back into community pharmacy services, generics expert and Sigma managing director Bharat Shah has said.

"I represented the short-line wholesalers as one of the signatories on category M [when it was brought in] and we were very clearly told that the money that came out would be recycled back into pharmacy services," Mr Shah told the Avicenna Conference this week.

The Department of Health (DH) had clawed back £1.176 billion in purchase profits since category M's inception in 2005, Mr Shah said. "I personally feel there hasn't been £1.2bn [put back] into services."

"PSNC is controlled by you as contractors – you must have a say" Bharat Shah, Sigma

Contractors to lose £2,250 in category M clawback Can category M survive the patent cliff? Category M Barometer

Mr Shah urged conference delegates to demand greater transparency in category M to allow them to plan their businesses. "PSNC is controlled by you as contractors – you must have a say," he said. And contractors should force a review to deal with what Mr Shah estimated to be a doubling of the category's volume, as well as anomalies in the system. The latter included the continued presence of exclusives (drugs with only one supplier) in category M.

Mr Shah predicted that the long-term problem of pack-size discrepancies in the category would finally be dealt with this year, with price per tablet set to be introduced in October.

But he reiterated calls for contractors to plan for large clawbacks over the next two years as blockbuster drugs come off patent. "Please plan for these big patent cliffs," Mr Shah advised. "Don't spend the profits – put proper provisions in your business."

Atorvastatin could be introduced into category M as early as the June tariff, he said, following Lipitor coming off patent. Mr Shah also believed that methadone mixture would be introduced into the category, also in June.

Find out how the latest category M tariff will affect your bottom line with the category M barometer.