Why hasn’t nirmatrelvir plus ritonavir been pre-placed from the National Medical Stockpile to RACFs, when it has been demonstrated to be more clinically effective?
Nirmatrelvir plus ritonavir has a large number of contraindications and drug-drug interactions. It has not been pre-placed in RACFs because it is not a suitable treatment option for many frail, older people living in these settings.5
The contraindications and drug-drug interactions for nirmatrelvir plus ritonavir include:8,9
- people with severe renal impairment (<30 ml/min)
- people with severe hepatic impairment (Child-Pugh Class C)
- people taking medicines that are highly dependent on CYP3A for clearance and for which elevated concentrations are associated with serious and/or life-threatening reactions. See Table 1 of the nirmatrelvir plus ritonavir PI for more information.
- people taking medicines that are potent CYP3A inducers where reduced nirmatrelvir plus ritonavir plasma concentrations may lead to loss of virologic response and possible resistance. See Table 2 of the nirmatrelvir plus ritonavir PI for more information
Further, dose adjustment is required for nirmatrelvir plus ritonavir in patients with moderate renal impairment.8
No contraindications (except for hypersensitivity to active substance and excipients), no drug-drug interactions and no situations requiring dose adjustment have been identified for molnupiravir.1 See the molnupiravir PI for more information.
There is no available head-to-head clinical trial evidence allowing direct comparison of the efficacy (or safety) of the two medicines. The TGA has found the efficacy and safety of both medicines sufficient in their indicated patient populations to allow provisional registration. Individual prescribers will be best placed to determine whether a particular medicine is suitable for a patient’s own clinical circumstances.
Distribution of oral antiviral medicines was consistent with the National COVID-19 Clinical Evidence Taskforce Living Guidelines at the time, which recommended prescribers consider molnupiravir ‘where other treatments such as sotrovimab (Xevudy) or nirmatrelvir plus ritonavir (Paxlovid) are not suitable or available.’
Clinicians should note that where infection with Omicron BA.2 is confirmed or considered likely, use of sotrovimab should only be considered where other treatments are not suitable or available. Currently, there is no clinical evidence to evaluate its effectiveness against the Omicron variant or BA.1 or BA.2 sub-variants.
Read more about how medical professionals can access COVID-19 treatments through the National Medical Stockpile.