Taoiseach Leo Varadkar has defended the Health Service Executive's decision to restrict Versatis patches.
The issue has been highlighted by patients who called RTÉ's Liveline programme.
Fianna Fáil leader Micheál Martin put it to Mr Varadkar during Leaders’ Questions that the Government sought to reduce costs, leaving people who need the patches in chronic pain.
Mr Martin called on the Taoiseach and Minister for Health Simon Harris to intervene and suspend the decision by the HSE.
The Taoiseach said a lot of people had contacted him about the issue and he discussed the matter with the Minister for Health last week.
He explained that the patches are licensed for adults who have shingles.
However, he said over the last number of years, doctors have been prescribing it for uses for which it is not licensed.
Mr Varadkar said the medication is an anaesthetic and there are long-term side-effects from anaesthetics.
"There are no problems if GPs are prescribing it for what it's licenced for," he said.
He said it was not a matter of money, but a matter of patient safety. He added the patch was being prescribed ten times more than it is prescribed in the UK.
"There's something wrong that medication is being used ten times as much as it is across the water," he said.
Mr Varadkar said the HSE decision was the right one from a patient safety perspective.
More than 2,300 patients have now been approved for the Versatis plaster under the drug schemes, Jim Daly, Minister of State at the Department of Health, has told the Seanad.
Around 1,500 post-shingles patients have been approved, as well as 850 approved for use other than post-shingles pain, based on the clinical case made by their GP.
Mr Daly said that the turnaround time for applications is three working days and for appeals it is five days.
He said that nearly two thirds of appeals for non-shingles patients have been granted on the basis of the clinical case made by the patient's GP.
Fianna Fáil Senator Jennifer Murnane O'Connor said that the scheme was changed without fair warning for patients.
She said the news came as a shock and surprise to patients for whom the patches had become a lifeline.
She called on the Department of Health to set up an immediate impact study of the change.
The plasters have been covered under community drugs schemes since 2010.
A new reimbursement system was introduced by the HSE from last September.
