One of the world's most expensive drugs is to be provided to more patients suffering from a life-threatening blood disorder even though the manufacturers have not reduced the price.

Eculizumab, brand name Soliris, costs €430,000 per patient per year and the HSE had been attempting to negotiate a reduced price with makers Alexion.

Patients had been battling to get the drug but the HSE felt the cost was exorbitant.

However, despite failure to reduce the cost, the HSE has now agreed to make it more widely available to sufferers.

The rare genetic condition is called paroxysmal nocturnal haemoglobinuria (PNH).

The HSE said that due to the cost of Soliris it would be provided for patients on the basis of clinical need.

HSE  Director General Tony O'Brien said it was an astronomical price to pay for any drug.

However, the HSE did not want the patients awaiting access to Eculizumab caught in the crossfire between a drug manufacturer attempting to enhance its profits and health authorities attempting to protect scarce money for delivering services.

It is expected that around four to six patients may benefit.

Sufferer John Duggan, from Bellewstown, Co Meath, said that he was thinking of emigrating before hearing Soliris was to become available.

Mr Duggan told Drivetime on RTÉ Radio that he had been having blood transfusions every four to six weeks.

The carpenter, who was first diagnosed with PNH in 2010, said Soliris was an expensive drug but it would save his life.

He said: "Well, without the drug I was in fear of clotting, having blood clots and having to be looked after. If I got a severe enough clot I'd have to be looked after for 24-hour care.

"Or, the work I was doing, I had a chance of having a heart attack, or kidney failure was another big one and I'd have to go on dialysis.

"But the biggest one doctors were really worried about - that was the clotting."

The screening process will commence immediately and individual patients are not required to take any action at this time.

Treating clinicians can apply to the HSE's Medicines Management Programme (MMP) in order to commence a screening process for patients.

The HSE said it had attempted to negotiate a more reasonable cost for Soliris, however, the manufacturer refused to agree.

Regular reviews to determine the effectiveness of the treatment and outcomes for patients will also be undertaken by the MMP.

The HSE said the high cost would impact on its ability to fund important other services and the recruitment of nurses.

Consequently, the HSE urged the manufacturer to reconsider the price.

The HSE said it would continue to pursue a more reasonable price for the medicine.

Around ten patients have been treated with the drug on a pilot basis here over recent years under an old agreement with Alexion.

Recently, more patients needing the drug have emerged but agreement could not be reached on the price.

In March 2010, the National Centre for Pharmacoeconomics concluded that Eculizumab was not cost effective and that HSE reimbursement under the High Tech Drug Scheme be rejected.

Later a complex agreement was reached between the HSE and Alexion under which, effectively, the HSE would pay €355,000 a year for a patient.

The deal was based on €4,557 per vial with patients requiring 78 vials a year.

At the request of the HSE, a re-evaluation of the drug was conducted by the national centre in October 2013 and it found that the total cost per patient per year for maintenance treatment would be €437,200.

It was estimated that the number of patients expected to receive the drug would increase from 13 in 2013 to 20 in 2017.

At that price, the centre said it did not believe the drug was value for money.