Special attention asked be paid to the prescribing of NOACs

The HSE’s Medicines Management Programme (MMP) has highlighted that attention should be paid by to the prescribing of  New Oral AntiCoagulants (NOACs) particularly in relation to appropriate dosing and the potential for drug interactions.

Over 13,000 patients receive treatment with NOAC drugs under the Community Drugs Schemes in Ireland. This represents a threefold increase over the past 2 years as prescribers consider the potential benefits including the predictable anticoagulant effect without the requirement for regular monitoring, lower rates of intracranial hemorrhage and the reduction in potential drug interactions.

The HSE said, “The NOACs are not without adverse effects and of course the most important is hemorrhage. The risk of major gastrointestinal hemorrhage may be even greater with NOACs as compared with warfarin and no antidote has been proven to immediately reverse the effects of these new agents. In March 2013 patient safety issues with the NOACs was highlighted in the Irish Medical Journal, with the recommendation that prescribers (frequently in the hospital setting) would need to carefully select their patients to optimize safety and efficacy.”

 In relation to rivaroxaban (Xarelto), currently there are 7,460 patients who receive the drug, with some 4,590 patients (62%) receiving it as long term therapy and over 16% of these patients (769) receiving the drug at a prescribed daily dose of just 10 mg.

The recommended dose for atrial fibrillation is 20 mg daily reducing to 15 mg daily for patients with renal impairment. Administration of rivaroxaban 10 mg daily is not indicated for atrial fibrillation and renders such patients susceptible to stroke.

When reviewing dispensing data (January – October 2013 inclusive) the MMP sought to identify prescribing patterns of NOACs in Ireland.

They specifically aimed to determine dosages prescribed to patients receiving long term NOAC therapy (treatment exceeding 35 days) and to investigate potential drug interactions. It was found that over 80% of prescribing of NOACs is for the atrial fibrillation indication and 60% of patients treated with NOACs are aged 75 years or more.

Over 28% of patients treated with rivaroxaban received medications that would be expected to interact with the anticoagulant. Over 100 patients were co-prescribed dronedarone which should be avoided given the limited clinical data available.

Some 25% of patients received medications where caution is advised e.g. NSAIDs and platelet aggregation inhibitors. This co-prescribing places patients at greater risk of hemorrhagic complications.