Patients are experiencing delays in receiving essential medicines and are having to use unlicensed products in the absence of the licensed version of a drug, it has emerged.
In some instances, medical card patients are paying for drugs rather than wait for reimbursement approval of the unlicensed medication.
Among the products that have been unavailable from manufacturers are vitamin B12 injections for the treatment of anaemia and morphine for pain relief.
Injectable drugs used in cardiac and respiratory emergencies, as well as a number of hormone replacement treatment (HRT) products, are also in short supply.
The medical card and drug payment schemes do not cover the cost of unlicensed medications and while medical card patients are entitled to apply for reimbursement from the local Health Service Executive, it can take a number of weeks for approval to come through.
Under the 1998 Medicinal Products Regulations, doctors may prescribe unlicensed medicines but are responsible for any problems that may arise as a result. Such medicines can only be supplied on an individual "named-patient" basis.
In a statement, the Irish Medicines Board said it agreed that tighter regulations were needed in the area of unlicensed medicines. It is in the process of appointing an expert to "examine the issues surrounding the use of unauthorised medicines".
A spokeswoman for the Department of Health said: "As soon as the department becomes aware of shortages in vital medicines, every effort is made to source an alternative product from a reliable source."
A number of Irish Times readers have experienced particular difficulties in getting vitamin B12 injections, an essential treatment for pernicious anaemia. In one instance, a woman travelled to Austria to secure an alternative supply of vitamin B 12.
Karl Hilton, president of the Irish Pharmaceutical Union (IPU), said he was concerned about the shortage of drugs and the risk it posed to the health of certain patients.
"It can be extremely inconvenient and pose a risk to the health of some patients to have to return to a doctor to have a new prescription written," he said. "It is up to the Department of Health and Children to ensure that patients in this country have continuity of supply of medicines and steps should be taken to ensure that shortages do not occur."
Séamus Ruane of Mervue Pharmacy in Galway city said patients faced a minimum two-day wait while an alternative unlicensed version of a drug was found.
He explained that unlicensed drugs could not be stocked by pharmacists and that a special order form had to be sent for each patient to one of two companies which specialised in sourcing unlicensed medication.
Dr Iftikhar Ali, regulatory affairs manager of UCB Pharma in Britain, the suppliers of vitamin B12 to the Irish market, told The Irish Times that the company that manufactured vitamin B12 (cytamen and neocytamen) on its behalf had refurbished its premises last year, giving rise to issues concerning the sterility of the manufacturing facility.
As a result, the products went off the market in the middle of 2005.
John Vaughan of Goldshield, which manufactures morphine and other injectable drugs, confirmed that there had been an interruption in supply but he said he expected all its products to be available again by the end of January.