GPs will be able to endorse any prescription to opt it out of the arrangements. But such substitution will not be able to take account of cases where branded drugs are cheaper than generic versions, the DoH has acknowledged.

The list forms part of the government's proposal for how generic substitution will be introduced in England, which is open for comments until 30 March.

GPC prescribing lead Dr Bill Beeby said that, although generic prescribing would save some money, it would have costs in terms of doctors' and pharmacists' time.

‘The better answer would be to make sure people are prescribing generically,' he said.

Practices with low generic prescribing rates can be identified, he said. ‘Work can then be done to increase their generic prescribing. That is professional activity that should be supported.'

Around 5% of prescriptions are for branded products for which a generic equivalent is available. The government believes that for around half of these a generic product would be clinically appropriate. But Dr Beeby said this figure was a ‘guestimate'.

Introduction of generic substitution will involve changes to NHS arrangements and devolved administrations will determine their own plans.

Click here for full details of the salts, strengths and forms included in the proposals which are listed in Annex A of the consultation document.