British drugmakers are launching a legal challenge to moves by the state-run National Health Service to switch large numbers of patients onto cheap generic prescription medicines.

The Association of the British Pharmaceutical Industry (ABPI) believes such schemes are potentially unsafe and primary care doctors are receiving additional payments to prescribe certain low-cost medicines in contravention of European law.

The industry group said it had started a judicial review and its lawyers had won permission to bring proceedings to court, although a hearing is not expected before the end of the year.

"For some time the ABPI has had serious concerns about a number of initiatives at primary care organization level, especially those that provide incentives for switching large numbers of patients to alternative treatments with the sole aim of reducing costs and with inadequate patient safeguards," it said in a statement.

It argues patients should have to give explicit consent for any switching rather than leaving them to object if they wish to do so.

A Department of Health spokesman said the government would rigorously defend the legal challenge.

Much of the furor surrounds the use of cheap generic versions of statin drugs, which are prescribed to people with high cholesterol to reduce the risk of heart attack and stroke.

"The NHS could potentially save 84 million pounds ($169.5 million) if it switched to low cost generic statins," the Department of Health spokesman said.

"These generic drugs are safe, of good quality and just as effective, and used to treat many millions of patients worldwide."

Drug manufacturers, however, contend not all statins are the same. Some newer ones, for example, have proved more effective in clinical trials than older pills. Leading branded statins still protected by patents include Pfizer Inc.'s Lipitor and AstraZeneca Plc's Crestor.

At the same time, companies are concerned that switching programs are set to spread more widely.

Pulse, a newspaper for doctors, said it had learnt that primary care organizations across the country were now extending mass switching to ACE inhibitors for high blood pressure, proton pump inhibitors for stomach acid and anti-platelet drugs for the prevention of blood clots.

The ABPI action -- which the group said might yet be suspended if the government changed tack -- opens a new legal front in industry challenges to current NHS medicines policy.

Last month, makers of Alzheimer's drugs went to court to challenge the decision of the National Institute for Health and Clinical Excellence to restrict access their products on cost-effectiveness grounds. A judgment in that case is awaited.