June 2022
Nirmatrelvir-ritonavir remains first line for treatment of COVID-19 in adults that have one or more risk factors and do not require supplemental oxygen.
Use the covid interaction checker veteransmates.net.au/covid-checker to assess the safety of nirmatrelvir-ritonavir in your veteran patient. If this combination cannot be used follow the decision tree at covid19evidence.net.au/wp-content/uploads/DECISION-TOOL-DT-FOR-ADULTS.pdf
Molnupiravir should not be used routinely for the treatment of COVID-19. It should be considered for use only if nirmatrelvir and ritonavir is contraindicated or otherwise unsuitable. Nirmatrelvir Plus Ritonavir Interaction Checker
As the COVID-19 pandemic evolves, the role of GPs is becoming even more important for managing at-risk patients in the community.
An estimated 35,000 DVA patients are considered at risk of progressing to severe illness and needing hospitalisation if they develop COVID-19 infection.
Vaccination continues to be the most important and beneficial intervention to prevent severe illness.1
Two oral antiviral medicines may help prevent hospitalisation in such patients. Nirmatrelvir and ritonavir (Paxlovid®) and molnupiravir (Lagevrio®) have been listed on the PBS for use in non-pregnant patients 18 years and older who have at least one symptom and have tested positive by polymerase chain reaction (PCR) or rapid antigen test (RAT) for COVID-19 and meet eligibility criteria.1, 2, 3
Nirmatrelvir and ritonavir www.pbs.gov.au/medicine/item/12996B
Molnupiravir www.pbs.gov.au/medicine/item/12910L
Covid antivirals are effective in reducing mortality.2, 4, 5, 6, 7 Nirmatrelvir and ritonavir (Paxlovid®) was significantly more effective in clinical trials than molnupiravir (Lagevrio®) at reducing hospitalisation (84% compared to 43%).1, 6 Both medicines must be started within 5 days of diagnosis and should be taken twice a day for 5 days.1, 3, 5, 8
Is the first choice in high-risk patients, but it has potential for significant drug interactions.3, 5, 6, 9, 10, 11
Potential interactions can be assessed using the COVID-19 medicine interaction checker www.veteransmates.net.au/covid-checker
Paxlovid® should not be used in severe hepatic and renal (eGFR < 30 mL/min) impairment and dosage must be reduced in moderate impairment (eGFR > 30 to 59 mL/min).3
Molnupiravir (Lagevrio®)
Although molnupiravir is not known to cause significant drug interactions and does not need dose adjustment in renal or liver impairment, it is significantly less effective than nirmatrelvir and ritonavir at reducing hospitalisation. Because it is potentially teratogenic, male partners of women of reproductive age should use barrier contraception for 3 months after finishing their treatment course.8, 11, 12, 13, 14
These medicines have been provisionally approved based on trials in unvaccinated adults with mild to moderate COVID-19. Evidence for their clinical efficacy and adverse effects continues to accumulate.15 For updated evidence see the COVID Living Guidelines at www.covid19evidence.net.au
Identify – Identify which of your patients may be at risk of progressing to severe illness.
Prepare – Talk to your patient via TeleMed or face to face (at their next scheduled appointment or organise a recall) about what they should do if they test positive for COVID-19, explaining the need for urgent review if they develop the illness. Check on their vaccination status.
Ask about over the counter medicines like St Johns Wort and recreational drugs.
Use the COVID-19 medicine interaction checker to assess if Paxlovid® can be used www.veteransmates.net.au/covid-checker
If an interaction is identified, the tool will provide one of six suggested actions:
If patient is on a combination product seek pharmacy advice about how to split the components. If the patient uses a Dose Administration Aid (DAA) e.g. Webster-pak®, liaise with the patient’s pharmacist to organise an alternative dose administration system while using nirmatrelvir and ritonavir.
Seek specialist advice if your patient is taking:10
Support – Offer subsequent visits to answer any concerns and create a plan should your patient become unwell outside of consulting hours. Advise them about using conservative measures to treat mild COVID-19 symptoms at home16 www.racgp.org.au/clinical-resources/covid-19-resources/clinical-care/covid-19-home-care-guidelines
Assess – If your patient tests positive, make sure they are safe to receive treatment at home. If their symptoms suggest that they are deteriorating, organise transfer to an emergency department.
Prescribe – If the patient consents to treatment, meets PBS criteria, is stable and safe to be treated at home, and does not have absolute contraindications, use nirmatrelvir and ritonavir (Paxlovid®) as first line.1, 2, 3, 5, 6, 10, 11 Organise medicine changes as planned (stop and restart potentially interacting medicines as per the interaction checker www.veteransmates.net.au/covid-checker).
Use molnupiravir (Lagevrio®) only if there are absolute contraindications to nirmatrelvir and ritonavir (Paxlovid®).
Although vaccinations have been shown to reduce the risk of long COVID, not enough evidence has been gathered to say whether COVID treatments also reduce the incidence of long COVID.17
Living guidelines at www.covid19evidence.net.au are constantly updated and contain clear and invaluable decision-making tools for GPs.