Doctors are ready to ignore new restrictions on the NHS prescription of the anti-impotence drug Viagra which they describe as "flouting the founding principles of the NHS".

Health Secretary Frank Dobson has said GPs can prescribe the drug to NHS patients, but only to people with certain physical or psychological conditions.

The ruling has been condemned by the British Medical Association as "cruel and unethical". The BMA said it was also conclusive proof of rationing in the NHS.

GP leaders told doctors across the country on Thursday that until the government guidelines were given the force of law they should prescribe Viagra to all patients who had a demonstrable clinical need.

Mr Dobson said the restrictions, which are subject to a six-week consultation period, should limit the cost of the drug to �10m a year. He challenged the BMA to come up with alternative proposals that would avoid Viagra draining scarce NHS funds.

Setting more money aside to make the drug more generally available would "take money away from paying doctors and nurses, dealing with cancer and people who have accidents," he said.

Those who will get Viagra on the NHS are:

• People who have undergone radical pelvic surgery or had their prostate gland removed;
• People with spinal chord injuries;
• Diabetics;
• People with multiple sclerosis and other single gene neurological disease which cause impotence.

The drug will not generally be available to other patients on the NHS, but people suffering from severe distress because of impotence will be able to get it if hospital doctors prescribe it for them.

Others can get it on private prescriptions.

Mr Dobson said Sweden was the only European country which was likely to make the drug freely available on its national health service.

His announcement came after doctors threatened to go ahead and prescribe the drug on the NHS anyway.

The British Medical Association's GPs Committee set the 21 January deadline to coerce the government into issuing guidance specifying which patients should be allowed to get Viagra though the National Health Service.

Last month the committee warned that it would advise GPs to disregard the current restrictions and routinely prescribe the drug to patients with impotence unless guidance was issued by this Thursday.

Dr John Chisholm, chairman of the BMA's GP Committee, said the government's guidelines flouted the founding principles of the NHS, and were not based on any sensible measure of clinical effectiveness.

He said it was "wholly unethical" to discriminate against patients with equal clinical need.

He said: "Patients deserve better of the NHS than this.

"This is a cruel and unethical decision that is making totally unjustifiable distinctions between good and bad, deserving and undeserving causes of impotence.

"Doctors are there to respond to their patients needs and as far as the patient is concerned they all deserve treatment that is available and effective."

Dr Chisholm warned that restrictions on the use of Viagra would lead to the hospital sector being deluged with patients referred by GPs for treatment denied them in primary care.

Dr Chisholm said doctors already prescribed many drugs for non life-threatening conditions and there was no reason to treat Viagra differently.

Approximately one in five GPs have already prescribed Viagra, although about 90% of prescriptions have been issued on a private basis.

Dr John Chisholm: GP action forced the government's hand

A spokesman for Pfizer, the company that makes the drug, said: "It is clear that the majority of people suffering from impotence will not be covered for NHS treatment by these new guidelines.

"This is a very restrictive and discriminatory decision and it seems that Mr Dobson has not listened to the expert medical advice which has come to him."

He added: "GPs in this country are notoriously cautious in their prescription habits, but we would expect the prescriptions to stabilise in around five years' time at a cost of about �50m per annum."

Liberal Democrat health spokesman Dr Evan Harris said: "It is astonishing that on the floor of the House of Commons on Monday the Secretary of State denied rationing of treatment on the NHS, and three days later he produces rationing guidelines on impotence treatments."

September ban

Frank Dobson says the bill should be limited to �10m a year

The Department of Health originally put out interim guidance on NHS prescription of Viagra in September, on the eve of the drug being awarded a licence for use as a medicine in Europe.

The guidance stated that the department preferred the drug not to be prescribed.

It followed fears that excessive demand could cost the health service more than �1bn a year.

UK doctors with private practices had been able to prescribe Viagra for some time before on a named patient basis. This is where the doctor takes personal responsibility for what happens to the patient.

At the time of the ban, Mr Dobson said the government would seek "further expert guidance" and definitive advice on prescribing would be issued in within a matter of weeks.

Currently, Viagra tablets are available privately, costing �12 each. The price to the NHS is �4.86 a tablet.