The HSE is considering making a formal complaint to the European Commission against a major pharmaceutical company over the price it charges for a life-saving drug.
Health service bosses have accused the American firm Alexion Pharmaceuticals of abusing its monopoly position following its refusal to reduce the price of anti-blood clotting drug, Eculizumab.
They believe the EU Commissioner for Competition, Margrethe Vestager, may initiate an investigation into the company's practices.
Known commercially as Soliris, Eculizumab is one of the world's most expensive drugs. Ten Irish patients had been using the drug on a pilot basis since 2010 at a total cost of €4m per year.
Last February, after protracted and ultimately unsuccessful negotiations aimed at lowering the price of the drug, the HSE approved the purchase of Soliris for an additional ten people at a cost of €420,000 per patient per annum.
A spokesman for the HSE told the Sunday Independent that it was considering its legal options as it seeks a better deal on the drug. "What we are actively considering is the lodgement of a complaint with the EU Commission," he said.
Alexion did not respond to a request for comment.
The disclosure came after documents released under freedom of information rules to Fine Gael TD Fergus O'Dowd detailed how senior HSE officials were scathing of the company's attitude during negotiations.
Senior officials described the company's refusal to budge on pricing as "unreasonable" and "exceedingly unhelpful".
They also warned that by approving the purchase of the drug there were likely to be other expensive life-saving medications which could not be purchased by the HSE in the coming years.
Mr O'Dowd said it was "imperative that vulnerable patients are given the drugs they need to save their lives."
He added: "At the same time, all action must be taken to ensure that the taxpayer is not held over a barrel by a pharmaceutical company."
In a confidential discussion document from last February, Dr Susan O'Reilly, the chair of the HSE's drugs committee, outlined the quandary they were faced with prior to deciding to approve the purchase.
"The drugs group does not know what the appropriate societal response is," she wrote.
"There are clinical grounds to support reimbursement but the pricing strategy of Alexion means that there are implications for future pharmaceutical decisions and other services."
In a separate briefing note for colleagues, John Hennessy, the HSE national director for primary care, recommended that the drug be bought for additional patients. He said this should be done in conjunction with "appropriate measures, including legal proceedings for abuse of monopoly position".
Mr Hennessy described the price as "exorbitant" and said "the behaviour of the company continues to be unreasonable in this regard". He added that it was "not appropriate that Irish patients would continue to be denied access to treatment and remain caught in an ongoing and protracted stand-off between the company and the HSE".
The drug is the first to be licensed for two rare conditions, paroxysmal nocturnal hemoglobinuria (PNH) and ahaemolytic uremic syndrome (AHUS).
For patients with PNH, the drug reduces the need for transfusions and improves quality of life.
For AHUS sufferers, the drug is crucial for successful renal transplants.