GPC prescribing subcommittee chairman Dr Bill Beeby said the figures released last week suggested many GPs had already achieved large savings, but further savings may be harder to come by.
Overall numbers of prescriptions dispensed in the community in 2010 rose to 926,658 across England, up 5% from 885,999 in 2009. The net ingredient cost rose to £8,834,380, a rise of 3% from £8,539,421 in 2009.
But as the number of prescriptions showed a greater rise than the cost, the net ingredient cost per prescription fell to £9.53, down from £9.64 in 2009.
'This reflects well on the prescribing behaviours of GPs, as they heed the need to contain costs by responsible choices of medication,' Dr Beeby said.
The Quality, Innovation, Productivity and Prevention (QIPP) agenda may have meant GPs were already using more cost-effective treatment options, he said. 'The new QIPP-related indicators for prescribing in the QOF are intended to have the same effect, though these figures may indicate that many have done the work and future savings may be smaller,' he added.
Dr Beeby said factors outside GPs' control would also mean that 'sometimes we will get lucky'. 'Just as we saw costs fall after simvastatin went generic, so we may see cost reductions as losartan has gone the same way and candesartan and atorvastatin will follow soon,' he said.
Data released by the NHS Information Centre showed that despite a rise in the number of prescriptions dispensed, the average cost of each prescription has fallen.
In some disease areas, prescription numbers have risen, but overall costs have dropped.
For cardiovascular therapies, the number of prescriptions rose 3% from 2009 to 2010, but overall spend on these fell by 7%. Treatments for malignant disease and immunosuppression showed a similar pattern.
For drugs to treat gastrointestinal system conditions, the number of prescriptions rose 14% from 2009 to 2010, but spending rose 2%.