By medical reporter Sophie Scott and Alison Branley
Australian health authorities have decided against recommending routine monitoring for patients on new blood-thinning medications used to prevent or treat blood clots.
The drugs in question are oral medications apixaban (Eliquis), dabigatran (Pradaxa) and rivaroxaban (Xarelto).
Figures obtained by the ABC last year revealed one of the new blood thinners, Pradaxa, had been associated with 280 deaths in Australia and 1,400 adverse drug reactions in the past five years, including abdominal bleeding, brain haemorrhages, strokes and heart attacks.
Medical experts say the side effects and death figures are disparate because Pradaxa is a new medication and there has been more reporting of adverse events from it compared to Warfarin.
Last year, a British Medical Journal investigation found the makers of Pradaxa withheld some of their internal analysis of the new “blockbuster” drug because they were worried it would affect sales.
The latest TGA review found there was no evidence to support a recommendation for routine blood monitoring to improve the safety of the new oral anticoagulants.
The health regulator said drug manufacturers had not undertaken dedicated studies to evaluate the effects of routine plasma monitoring on the safety profile of their medicines, so monitoring would not be helpful when determining a patient’s bleeding risk.
“Therefore, the TGA’s review has found there is no evidence at this time to support a recommendation for routine plasma monitoring in patients being treated with these medicines,” it said.
It said plasma monitoring may be useful in some clinical circumstances such as overdose or emergency surgery.
In 2013, the Therapeutic Goods Administration warned doctors of the need to carefully consider each patient’s risk factors for bleeding and observe the dosage recommendations, contraindications and precautions for use when prescribing the new blood-thinning drugs.
“Clinical trials and post-marketing experience have shown that major bleeding events, including those leading to death, have occurred with all of these products and with other anticoagulants,” it said.
One of the main downsides of the newer drugs is there is no specific antidote available for these medicines.
The makers of Pradaxa are trialling an antidote which could switch off the drug’s anticoagulant effects if patients suffer a serious bleeding episode.