Fears over switch to cheap drugs

London: Millions of patients could face life-threatening side-effects under a scheme which will swap branded drugs for cheaper versions.

More than five million asthma sufferers and up to 500,000 with epilepsy could be hit by the change, while patients with conditions such as Parkinson's, bipolar disorder and hypertension may also Pharmacists will be expected to substitute a brand of drug written on a prescription with a generic, cheaper version.

For the first time, outside an emergency situation, they will not have to consult with a doctor to change a patient's prescription. The plan is expected to save the NHS up to £70million (Dh411 million) a year, but critics claim it may end up costing more in treating side-effects unless certain medical conditions are exempt from the rules.

Generic products are developed to cash in when branded drugs lose patent protection. Although generics are meant to be identical, the active ingredients can vary within an agreed percentage and inactive ingredients.

In epilepsy even tiny changes in bioavailability - the amount of active medication absorbed into the body - can have serious consequences. NHS guidelines on epilepsy drugs currently warn against changing the brand for individual patients because of "increased potential for excessive side-effects".

New regulations will be implemented next January, but no patient groups have been consulted. Doctors claim it is vital the 5.4 million asthma sufferers in the UK are protected from having their inhalers automatically switched to cheaper versions.