New covid oral drugs: what GPs want to know

6 minute read

GPs around the country are expected to begin prescribing the two new medications within a matter of days.

GPs around the country are expected to begin prescribing two new oral treatments for covid within days. 

The first batches of molnupiravir (Lagevrio, Merck Sharp and Dohme) and nirmatrelvir+ritonavir (Paxlovid, Pfizer) arrived in Australia earlier this month, after receiving provisional approval from the TGA in January. 

Both antivirals are indicated for the treatment of mild to moderate covid in adults aged over 18, who do not require supplemental oxygen, and who are at increased risk of progression to hospitalisation or death.  

Treatment must start within five days of the onset of symptoms. 

The bulk of the first stocks of molnupiravir headed to Australian aged care facilities, where they can be prescribed by GPs.  

Aboriginal Community Controlled Health Organisations will be receiving stocks of both nirmatrelvir+ritonavir and molnupiravir. The remaining nirmatrelvir+ritonavir will be distributed to states and territories through the National Medical Stockpile for prescribing to patients in the community. 

Deputy Chief Medical Officer Professor Michael Kidd said it would be up to each state and territory to decide how the medication would be distributed. 

However, nirmatrelvir+ritonavir will not be for everyone.  

While it is indicated for patients with one or more risk factors, including people who are aged over 60 and/or have diabetes, obesity, cardiovascular disease, hypertension, and chronic lung disease, the list of contraindications and drug-drug interactions is much longer. These include some statins, anti-seizure medications, anti-inflammatories, sleep medications, blood pressure medications, anti-depressants, allergy medications and blood thinners.  

It is also not recommended for patients with severe liver or kidney disease but can be prescribed at a lower dose for patients with moderate kidney disease. 

By comparison, molnupiravir has fewer drug interactions, and is indicated for patients who do not require oxygen; and who are unvaccinated and have one or more risk factors for disease progression; or who are over 60 or have chronic health conditions; or who are immunosuppressed or not immunocompetent regardless of vaccination status; or who have received one or two doses of vaccine and are at high risk of severe disease due to age and multiple risk factors; and where other treatments (such as sotrovimab or nirmatrelvir+ritonavir) are not suitable or available.

There are no known drug interactions so far identified with molnupiravir and the most common side effects are diarrhoea, nausea, and dizziness. The oral antiviral is not recommended in pregnancy, and patients must use effective birth control while on treatment and for four days after stopping if there is a possibility of them getting pregnant. The same applies for breastfeeding. 

It is also recommended that men who are having sex with women of child-bearing age should use a reliable method of contraception during treatment and for three months after their last dose.  

Professor Kidd joined RACGP President Dr Karen Price and ACRRM President Dr Sarah Chalmers, in a webinar last week, where he answered GPs’ questions about the new antivirals. Here is a selection. 

Can we cease other medications if drug-drug interactions are identified, so that people can access the treatment? 

The challenge with many of these medications is that there’s a washout period after you cease them and that may well take you beyond the time when these treatments are going to be able to be beneficial or effective. And you do want to start them as quickly as possible once you’ve made a decision to use them. You don’t want to be waiting days because in that time someone may have already clinically deteriorated. 

Why are these drugs contraindicated in those who have had a booster? 

To date there’s not been any research conducted into the use of these medications in people who’ve had a booster dose of a covid vaccine. So there is literally no evidence showing benefit. 

How soon after treatment can you get immunised?  

These are anti-viral treatments, and they should not interfere with the vaccinations as far as we know. 

What kind of prescription is required and how will patients collect their medication? 

If you’re prescribing through residential aged care facilities for your patients who are there, it’s the same prescribing that you would normally do. If you’re prescribing through the states and territories it will depend on how it is being distributed [by them]. It may actually be a referral from you and then the prescription is made by one of the chief medical officers [in the relevant state or territory]. We won’t be doing normal prescriptions until this is on the PBS and we require the individual drug companies to advance their applications, then it gets assessed through the Pharmaceutical Advisory Committee before a decision is made on the PBS. 

How will consent be managed for pre-placed treatments in residential aged care facilities, particularly those patients with mental incapacity or cognitive impairment? 

The guidance to all aged care facilities is recommending consideration of arranging consent in advance of people becoming infected or of outbreaks occurring, so that discussions can be had between the staff and either the resident or their family members or other decision-makers about if you become infected with covid and develop symptoms, would you consent to your GP being approached to assess whether these treatments may be appropriate. 

How will triage work in the community? 

It is going to differ by state and territory. It may well differ within the state and territory depending on the arrangements by local public health units and local health districts within the state and territory where you’re based. There will only be a very limited supply of the medicines through the states and territories over the coming weeks as we get more and more supply into the country. Hopefully, there will be more capacity for utilisation outside of the priority settings that we’ve been talking about. 

Are these treatments going to be effective in decreasing long covid? 

We don’t have any evidence on that at this time. There will of course be continuing research. 

Have either been tested against the Omicron strain? 

To date no, the trials were carried out mainly against the Delta strain in the latter part of last year.

Can they be used as treatment for reinfection? 

This is an area where there is no research evidence available to us at the moment. And remembering that the treatments should only be used in people who are symptomatic and have mild to moderate symptoms. 

How effective will they be against future variants? 

We don’t know that – they are antivirals and it depends on the variant.

Consumer medicine information for nirmatrelvir+ritonavir is available here.  

Consumer medicine information for molnupiravir is available here. 

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