Allowing generic substitution by pharmacists will save up to £72 million a year, the government believes.
A DoH spokesman told GP that, if introduced in January 2010 as planned, generic substitution would cut by 0.4 per cent the year's primary care drugs bill, rising to 0.9 per cent in 2013.
This is a saving of £72 million in 2013, and an average saving of £50 million a year over the first four years of the scheme, if other planned cost cuts are introduced and prescribing rates continue to rise.
Discussions with doctors, pharmacies and generic drug manufacturers over the plans have begun, the DoH said.
Proposals to allow generic substitution were announced as part of last November's drug pricing agreement between the government and the pharmaceutical industry.
This would allow pharmacists to dispense a generic drug against a prescription for a branded medicine.
It is expected that a prescriber would have to tick a box, or indicate in some other way, to block such a substitution.
Final arrangements on how the system will operate still have to be decided, but will be informed by discussions with stakeholders, including doctors, pharmacies and manufacturers.
Dr Bill Beeby, GPC prescribing lead, said he thought saving more than 0.4 per cent was unlikely.
'The question is whether this is the best method of achieving that saving,' he said.
Inappropriate switching by pharmacists could put patients at risk, and new exemption categories and computer systems would be costly, he said.
Comment below and tell us what you think