Slimming pills prescribed for thousands of patients at private clinics are to be banned because medicine authorities say they do not work.
Doctors and pharmacists have been told that phentermine, marketed in Britain as Ionamin, and amfepramone, marketed as Diethylpropion, must be withdrawn from use within a month and that no new patients can be given the treatment.
The drugs' licences are being revoked across the European Union, but suppliers are planning legal action. A leading chain of clinics yesterday disputed suggestions that phentermine, the more widely used of the two drugs, did not work.
The government's medicines control agency said yesterday that a European review of slimming drugs concluded that some did not help people lose weight effectively.
"Although no new safety problems were identified with these drugs, some other anorectic products have been previously associated with heart and lung problems in some patients. A possible link with amfepramone and phentermine products cannot be totally excluded."
Five years ago, British authorities advised against banning such products because there was not enough evidence of significant harm to the public as a result of inappropriate use. But the British National Formulary, the drug "bible" published by the British Medical Association and Royal Pharmaceutical Society does not recommend phentermine for routine management of severe obesity. It says "rapid weight relapse" frequently occurs after short-term use of appetite suppressants that are only licensed to be prescribed for up to three months.
Phentermine, for which the licence was temporarily withdrawn last year, is hardly used in the NHS as newer (and more expensive) drugs are now available. One, orlistat, a fat-blocker, has been given limited backing for NHS use by value for money advisers.
Robert Houtman, director of National Slimming Centres, which has 33 clinics and 80 doctors, suggested the problems for phentermine were "political rather than medicinal".
"Patients so far have shown a marked preference for phentermine. It is noticeably effective. It does take the appetite away and it does help reduce craving for food. It is also less expensive for the patient."
Mr Houtman said that consultation and treatment with phentermine at the clinics cost about £13 a week, but the alternative would cost between £19 and £23. Price mattered because most patients were women from lower socio-economic groups.
Cambridge Healthcare Supplies, which estimates it produces enough phentermine for 20,000 patients a month, said the drug had been in use for more than 30 years. "There is no evidence of a safety risk. It does work although it may not be the fastest drug in the world. Patients like it because it has fewer side effects than alternatives."
• Safety warnings are to be issued over the use of Sporanox, a widely prescribed drug for fungal infections after manufacturers Janssen-Cilag alerted the MCA to a small risk that it could cause heart failure in patients. Its studies, linked to trials to develop intravenous alternatives to capsules and liquid treatments, found the drug weakened the force of the heart's contractions.
