Molnupiravir scripts double those for Paxlovid

4 minute read

This flouts the guidelines, but GPs and ID specialists say the guidelines are outdated and underestimate the challenges of Paxlovid.

Half a million scripts for molnupiravir (Lagevrio, MSD Australia) have been issued since national guidelines were updated by the covid taskforce to suggest the antiviral should “not be routinely used”.

Molnupiravir has been prescribed at almost double the rate of nirmatrelvir-ritonavir (Paxlovid, Pfizer), the only other oral covid antiviral on the Pharmaceutical Benefits Scheme, which requires a time-consuming medication review to avoid adverse interactions.

But according to GP and director of infectious diseases at Mater Health Services in Brisbane Professor Paul Griffin, the taskforce’s advice and the national guidelines are now out of date.

“The intent [of the taskforce’s statement] was to try and prioritise Paxlovid given it probably had superior efficacy,” Professor Griffin told The Medical Republic.

“But I think a lot of people, including the taskforce, underappreciated the challenges in prescribing [Paxlovid], particularly for busy primary care practitioners who have very limited time.

“And there was additional evidence that came out [after the statement] that suggested that the difference in efficacy between [Paxlovid and Lagevrio] was perhaps less than the paper that was used to make that recommendation suggested.”

According to numbers provided to The Medical Republic by the PBS, there have been 819,090 subsidised scripts of molnupiravir issued between its listing on the PBS in March 2022 and 31 December 2023.

This is up by almost 500,000 scripts since 2 December 2022, when the National Covid-19 Clinical Evidence Taskforce issued its statement that molnupiravir should not be routinely prescribed.

There have been 425,008 prescriptions of nirmatrelvir-ritonavir issued through the PBS since its listing in May 2022 and the end of 2023, about half that of molnupiravir.

According to Professor Griffin, one reason Lagevrio prescriptions exceed Paxlovid is the latter’s extensive list of drug interactions that is “unrealistic” to expect GPs to remember, meaning due diligence can take longer than the time available.

In a statement to TMR, RACGP President Dr Nicole Higgins concurred that Paxlovid’s contraindications can mean Lagevrio is the only option for some patients and that “PBS eligibility for Lagevrio is broader than the taskforce recommendations”.

“The latest recommendation on the use of Lagevrio is, ‘do not routinely use molnupiravir for the treatment of covid-19′,” she said.

“However, the taskforce has stated that there may be specific circumstances for the highest risk patients, where all other treatment options are contraindicated or inappropriate, in which non-routine use of Lagevrio might be considered.

“While funding ended for the National Clinical Evidence Taskforce on 31 July 2023, that advice is still current in the Australian Living Evidence Collaboration’s living guidelines for covid-19.”

When contacted by TMR for guidance on where to find current guidelines for prescribing antivirals, the Australian Commission on Safety and Quality in Health Care, whichfunded the national taskforce, said it could not comment and deferred to DoHAC.

The ACSQHC took over the quality use of medicines function from the defunded NPSMedicinewise.

DoHAC, in turn, deferred to the colleges.

“The Department of Health and Aged Care does not author clinical guidelines for the treatment of covid-19,” it told TMR.

“Clinical guidelines are generally developed by medical expert groups (e.g. specialist colleges, such as the Royal Australian College of General Practitioners) to help guide those in the profession.”

The RACGP suggested GPs visit its advice page.

But according to Professor Griffin, the lack of national guidance leaves a “huge gap”, rendering prescribers “stuck” and leaving individual facilities to come up with their own guidance, which is “highly impractical” and “very inefficient”.

“The colleges are often very poorly resourced in terms of actually coming up with guidelines and their role is more for endorsing and distributing them,” he said.

“A lot of people are probably prescribing in accordance with very dated guidelines.”

While the rate of change of the evidence may not be quite what it was at the height of the pandemic, meaning that completely reinstating the taskforce might be overkill, a national body to assimilate and disseminate information could provide much needed consistency and efficiency for busy GPs, Professor Griffin said.

On the topic of guidance for covid antiviral prescription, Professor Griffin added a reminder to GPs that antivirals are most effective when prescribed early.

“I think it would be something to really think about: how we can streamline access to testing and access to antivirals so that they can be given much earlier in the course of the infection, which is when they have the greatest benefit,” he said.

“To me that’s the biggest challenge at the moment.”

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