The drug, interferon beta-1a, is the latest in a new generation of treatments for patients who suffer chronic relapses of multiple sclerosis (MS).
Like other drugs of this type it is expensive - costing about pounds 9,500 a year per patient. MS experts have said that they feared many of the 8-10,000 patients who could benefit from the drug will be denied it because of the cost. Only about one-tenth of that number are said to be now receiving one of the two other drugs available.
With two more drugs soon expected to make an appearance, pressure on hospitals and health authorities to provide treatment for this disabling disease is likely to increase.
About 100,000 people in Britain suffer from MS, a disease of the central nervous system which causes numbness, pins and needles, tremors and paralysis. There is no cure, but a particular form of MS characterised by interspersed remissions and relapses and affecting up to 10,000 people is treatable.
In trials the drug, self-administered by under-the-skin injection, has been shown to cut the number of relapses suffered by patients by one-third, to reduce the severity of relapses, and to prolong the periods of remission.
Richard Hughes, professor of neurology at Guy's Hospital in south London, and one of the leading scientists involved in the trials, believes the drug's effectiveness strengthens the case for more spending on MS treatment.
He said: "For the first time we are seeing a breakthrough in the treatment of MS. The trials show conclusive evidence of benefit. I think it should persuade the health authorities to make the drug available for patients with this type of MS."
Peter Cardy, chief executive of the Multiple Sclerosis Society, said: "People with MS are still facing a postcode lottery on new drug treatments and services generally. While some health authorities make the new drugs available to all who are prescribed them, some refuse to fund them at all. The situation is unfair and unacceptable."
John Simpkins, chief executive of another MS charity, the Multiple Sclerosis Resource Centre, said: "MS has never had such a range of treatments available as it has now, but people aren't getting them.
"We fear that this latest one, which has had very good test results, is going to suffer the same fate as the other two. Only a tiny fraction of those who can benefit will get the treatment in some areas and others won't get it all."
He said a wider view should be taken of the cost-effectiveness of such drugs, taking account of what people disabled by the disease cost social services and the fact that treatment can help many sufferers continue to work.
"Two more drugs like this are coming along. How is a neurologist going to cope with the pressure from patients who have such a choice of things to ask for?" he said.
MS is a progressive disease, with symptoms ranging from numbness and tingling to paralysis and incontinence. The symptoms are caused by the destruction of patches of myelin - a protective covering which coats nerve fibres rather like plastic insulation around an electrical wire - in the sufferer's brain and spinal cord. The myelin is destroyed because the body's immune system turns on itself, perceiving the myelin as foreign and attacking it.Reuse content