Use of warfarin is in decline

But NOACs have contributed to an overall growth in the anticoagulant market

Based on the volume of prescriptions, use of novel oral anticoagulants (NOACs) in Australia has grown since their listing on the PBS for non-valvular atrial fibrillation (NVAF).

Use of the drugs was investigated by the Drug Utilisation Sub-Committee (DUSC), a branch of PBAC that assesses estimates on projected usage and financial cost for medicines.

It found that in the first year of listing, the predicted number of patients and prescriptions for NOACs was overestimated.

However, in the second year of listing, patients and prescriptions were close to predicted and saw overall growth.

The numbers show that in 2015, there were 1.6 million PBS-subsidised NOACs supplied for treatment of NVAF.

This was for 188,130 patients and for about 40% of these, it was their first NOAC prescription.

Three NOACs — dabigatran, rivaroxaban and apixaban — were listed by the PBS in 2013.

Since this time use of warfarin has declined, according to DUSC.

Several studies have shown that NOACs are at least as good as, if not better than, warfarin in terms of bleeding and other adverse effects, say the authors of a letter published in JAMA on August 9.

While warfarin is associated with multiple drug and food interactions, non–vitamin K oral anticoagulants do not require drug monitoring and have similar or improved safety and efficacy relative to warfarin, they say.

However, researchers of a study published in the MJA early this year say prescribers need to remain vigilant to the risk of bleeding with NOACs, particularly in patients who are taking other medicines that might increase bleeding risk.

“The overall increased use of oral anticoagulants since the introduction of NOACs may reflect use in patients who were previously considered unsuitable for treatment with warfarin,” they write.

Other DUSC findings

Glaucoma prescriptions increasing

The number of PBS and RPBS prescriptions for glaucoma medicines has increased steadily over the past decade.

In 2015, over 4.3 million prescriptions for these medicines were supplied.

Supply of fixed dose combination (FDC) products as a proportion of all glaucoma medicines also increased, from 9% in 2004 to 30% in 2015 – with over one million more FDC prescriptions supplied.

“While the majority of patients who start a glaucoma medicine do so with a single ingredient medicine, a small but increasing group of people appear to be starting treatment with a FDC product,” says DUSC Chair, Professor Geoff McColl.

Medicines for prostate cancer treatment increasing

The total number of patients receiving a medicine subsidised for use in the treatment of metastatic castration resistant prostate cancer (mCRPC) has increased substantially.

They have gone up from 1,418 patients in 2013 to 4,165 in 2015 – an almost 200% rise in just two years.

Professor McColl says the factors which may be involved in the changing treatment paradigm for prostate cancer include:

  • Expanding treatment options;
  • Regulatory approval for use of abiraterone and enzalutamide in chemotherapy naïve CRPC patients; and
  • Emerging trial evidence investigating hormonal therapies as an alternative or additive to chemotherapy.

Upcoming reviews

DUSC has requested that reviews of antipsychotics, testosterone and osteoporosis be prioritised for their upcoming meeting in September.

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