Irish drug company Elan yesterday secured European approval for its multiple sclerosis (MS) drug Tysabri. The company and its US partner, Biogen Idec, expect to have stocks available in Ireland next month.

"This decision means that patients in Europe who are suffering this chronic debilitating disease now have an effective new treatment alternative," said Elan chief executive Kelly Martin.

However, it remains unclear how soon Irish patients will receive the drug. The drug will be administered at hospitals and there is no provision for the €21,000-€22,000 annual cost per patient in current budgets.

Multiple Sclerosis Ireland yesterday welcomed the approval, which had been expected following a similar move in the United States earlier this month.

"The news offers great hope to those living with relapsing-remitting MS in Ireland," said Louise Wardell, chairwoman of the support group. "As there is yet no cure for MS, any drug that relieves symptoms and/or slows down progression is welcomed by those of us living with MS."

MS Ireland says there are 6,000 patients with the disease in Ireland. However, not all will be able to benefit from the drug.

Prof Michael Hutchinson, clinical neurologist at St Vincent's University Hospital, said the number with the relapsing remitting form of the disease was closer to 1,000-1,500.

He expects the people electing for treatment with Tysabri would be those suffering more regular and severe relapses, those displaying adverse reaction to existing treatments or people suffering accelerating disability

"Cleary this is a very effective drug," said Prof Hutchinson, "but there will naturally still be some caution in light of the previous incidence of PML."

Two trials patients taking Tysabri with other drugs died and a third fell seriously ill from the rare brain disease - an event that led to the withdrawal of Tysabri from US shelves just months after its accelerated approval in November 2004.

However, Prof Hutchinson, who oversaw the treatment of 10 Irish patients on one of the trials, said they had all returned to Tysabri as soon as trials were resumed earlier this year.

"The most important thing in MS is to stop the inflammation early on because this is what triggers the relapses," said Prof Hutchinson. "Tysabri is much more effective in preventing these inflammations - twice as effective as rival drugs.

"Confidence in the drug will grow as its use increases and the patient population grows."

He estimated that between 25 and 50 Irish patients could be using the drug by the end of the year, if hospital funding allowed.