Some leading specialists have stopped prescribing the drug in all but the most extreme cases, in the wake of a study in April which showed that high dosages increased mortality rates.
The study has thrown doctors into an ethical quandary because the drug appears to improve the quality of life of patients with congestive heart failure, by relieving breathlessness.
According to one heart specialist: 'Everybody is being more cautious about Manoplax since the study. I've stopped prescribing it to anybody, except for a few patients whose symptoms are so bad that they are prepared to take the risk.'
The City has also been unnerved because extra details of the study, promised within a month of the 26 April announcement, have not been forthcoming.
Boots has spent pounds 100m developing the drug over the past 12 years, including extending its factory in Cramlington, Tyneside. Last year it earmarked a further pounds 20m for marketing expenditure.
Shareholders of Boots, which is expected to report annual profits of about pounds 400m before tax tomorrow, have had high hopes for the drug. City analysts have predicted annual sales of dollars 200m and profits of dollars 75m by the late 1990s.
However, five weeks ago Boots announced that a study of 3,500 patients showed that those taking 100mg a day had a 'significantly increased risk of death'. It put a brave face on the findings and hoped that doctors would continue to prescribe in lower dosages.
But according to the specialist: 'It puts us in a difficult position. Until we know for sure that the lower dosage is not similarly associated with higher mortality, it is difficult on ethical grounds to prescribe it, and certainly not without putting the full facts before the patient.'
It was not clear whether the lower (50mg) dosage was effective: 'Whatever it is about Manoplax that makes you feel better may be the same thing that makes you die quicker.'
Mike Gates, a spokesman for Boots, declined to quantify sales since the study: 'Manoplax is still being sold, but obviously it's an area of acute sensitivity.' He said that the 50mg dosages seemed to work and that fewer than 20 per cent of patients had been on the 100mg dosages.
The study may lead to Manoplax being prescribed only in extreme circumstances. Doctors draw a parallel with Xamoterol, made by Zeneca, a drug seen as the 'great white hope' for heart disease, before disappointing mortality studies.
The failure of Manoplax would lead to more embarrassment for Boots, whose Do It All and Children's World stores have been losing money.Reuse content