Paxlovid (nirmatrelvir plus ritonavir)

Adults who have mild to moderate COVID-19 confirmed by a PCR or medically verified RAT and who can start treatment within five days of symptom onset, can be prescribed PBS-subsidised Paxlovid if:

• they are 70 years of age or older*
• they are 50 years of age or older with two other risk factors for severe disease
• they identify as Aboriginal or Torres Strait Islander origin, and are 30 years of age or older with one other risk factor for severe disease; or
• they are 18 years of age or older and moderately to severely immunocompromised.

• living in residential aged care
• living with disability with multiple conditions and/or frailty (but not limited to living in supported accommodation)
• neurological conditions like stroke or dementia and demyelinating conditions e.g. multiple sclerosis, Guillain-Barre Syndrome
• chronic respiratory conditions including COPD, moderate or severe asthma
• obesity or diabetes (type I or II requiring medication)
• congestive heart failure, coronary artery disease, cardiomyopathies
• kidney failure or cirrhosis (noting that Paxlovid is contraindicated for patients with severe renal failure or hepatic impairment (see Contraindications))
• living remotely with reduced access to higher level healthcare.

• blood cancer or some red blood cell disorders (thalassemia, sickle cell disease)
• transplant recipient
• primary or acquired (HIV) immunodeficiency
• chemotherapy or whole-body radiotherapy in the last 3 months
• high dose corticosteroids or pulse corticosteroid therapy in the last 3 months
• immunosuppressive treatments in the last 3 months
• rituximab in the last 12 months
• cerebral palsy or down syndrome
• congenital heart disease
• living with disability with multiple conditions and/or frailty.

When prescribing Paxlovid via the PBS, ensure the patient meets the eligibility criteria outlined on the PBS listing.

You can review the National Clinical Evidence Taskforce recommendations for the use of Paxlovid and their one-page summary flowchart on prescribing considerations for Paxlovid.

The standard dose of Paxlovid is 300 mg of nirmatrelvir (two 150 mg tablets) together with 100 mg of ritonavir (one tablet). All tablets must be taken together, with or without food. The tablets should be swallowed whole and not chewed, broken or crushed.

The tablets are dispensed in pre-dosed blistered cards.

Paxlovid is taken every 12 hours for five days. If patients miss a dose, they should not take a double dose to make up for the missed dose and should take their next dose as scheduled. Patients should not stop taking Paxlovid or change their dosage without speaking to their GP or physician.

Dosage adjustment for patients with renal impairment

Patients with moderate renal impairment (eGFR ≥30 to <60 mL/min) can be prescribed a lower dose of 150 mg nirmatrelvir (one tablet) with one 100 mg tablet of ritonavir. Paxlovid is contraindicated in patients with severe renal impairment (eGFR <30 mL/min). Refer to the product information for further details on dose adjustment.

Patients receiving an adjusted dose must be made aware that as the tablets are dispensed in pre-dosed blistered cards, only one tablet of nirmatrelvir with the tablet of ritonavir should be taken every 12 hours.

Paxlovid is contraindicated for patients with severe renal (eGFR <30 mL/min) or severe hepatic impairment (Child- Pugh Class C), and those who are allergic to nirmatrelvir or ritonavir or any of the ingredients listed in the product information, including:

• microcrystalline cellulose
• lactose monohydrate
• croscarmellose sodium
• colloidal silicon dioxide
• sodium stearyl fumarate.

 The following medicines are contraindications to Paxlovid. People taking these medicines should not be prescribed Paxlovid.
 

The following medicines have established and potentially significant interactions with Paxlovid and may cause serious or life-threatening side effects or affect how the medicine works. Refer to the clinical comments in the Paxlovid product information for each of the medicines listed below.
 

Paxlovid is not recommended during pregnancy and in people of childbearing potential not using contraception. Breastfeeding should be discontinued during treatment with Paxlovid and for seven days after the last dose.

As with most medicines, Paxlovid can cause side effects and, though most of these will be minor and temporary, more severe side effects may need medical treatment. The most common side effects of Paxlovid include vomiting, diarrhoea, headache, high blood pressure, aching muscle, muscle tenderness or weakness not due to exercise, and changes in taste or a metallic taste in the mouth. Patients should be advised to speak with their GP or prescribing physician if they are concerned about any side effects while taking Paxlovid.