A dispute over the payment of pharmacists for drugs has cost the taxpayer £46 million, Stormont assembly members said.
The Department of Health and community dispensers have failed to reach agreement on the terms of a revised contract covering reimbursement.
Stormont's Public Accounts Committee (PAC) said primary care prescribing costs £460 million each year - around 10% of all health and social care expenditure - but acknowledged a significant reduction in the overall cost of prescribing.
It said: "It is unacceptable that the Department and community pharmacists have failed to reach agreement on the terms of a revised reimbursement contract.
"This must be resolved as a matter of urgency."
Had the Department been successful in agreeing implementation of the new contract (which is in place elsewhere in the UK) in 2006, £46m and £550,000 in legal costs would have been released to provide additional, patient-focused pharmaceutical services in the community, the committee report added.
Community pharmacists in Northern Ireland refused to provide information to allow the Department to set the terms of the revised contract.
Despite failing to reach agreement, the Department nevertheless effectively introduced the revised contractual arrangements by using the Scottish Drug Tariff (agreed as part of the revised reimbursed contract with pharmacists in Scotland), the report said.
However in 2010, a judicial review concluded that by continuing to apply the Scottish Drug Tariff in Northern Ireland, in the absence of an agreed contract, the Department had failed to meet its statutory duty to provide fair and reasonable remuneration to community pharmacists. A subsequent judicial review also found in favour of community pharmacists.
The judicial review process cost the Department £550,000.
"As a result of the Department's failure to agree the new pharmaceutical contract, £46m (which could have been released to provide additional, patient-focused pharmaceutical services in the community - similar to other parts of the UK) had to be repaid to pharmacists."
The Health and Social Care Board has achieved savings in the four years since the general pharmaceutical budget was devolved from the Department. Between 2006 and 2013, the cost of prescribing in Northern Ireland has reduced by 18% in real terms.
Some £14m could have been saved by prescribing less costly drugs.
Chairwoman Michaela Boyle said: "My committee was surprised to learn that, for a number of common diseases, GPs here tend to prescribe more expensive generic versions of drugs compared to their counterparts in England, Scotland and Wales.
"If the most effective and least costly drugs had been prescribed, it would have saved £8.9m in 2012 and £5.1m in 2013."
The Comptroller and Auditor General, in his 2014, report calculated that by reducing the average cost per 1,000 NIPU (Northern Ireland Prescribing Unit) by 10% over a three-year period, savings of £54m could be generated.
The committee found that if local GPs reduced their prescribing of Pregabalin - which is used to treat epilepsy, neuropathic pain and generalised anxiety disorder - to the level prescribed in other jurisdictions, the health service would have saved over £8.5m in 2012 and £9.7m in 2013.