Britain’s health regulator has issued a warning about Covid-19 medication Paxlovid and the potential for risk of harmful drug interactions because of the ritonavir component – due to its inhibition of the enzyme CYP3A that metabolises many commonly used drugs.
The Medicines and Healthcare products Regulatory Agency (MHRA) has recommended prescribers obtain a detailed patient history of current medications before prescribing Paxlovid.
Ritonavir is a potent CYP3A4 inhibitor that acts to boost the plasma levels of the nirmatrelvir component of Paxlovid by preventing its degradation; as many commonly used drugs are metabolised by CYP3A4, the risk of harmful drug interactions with Paxlovid is significant, it said.
Additionally, drug interactions may also reduce its effectiveness in the treatment of Covid-19.
While the drug was approved for use in South Africa earlier this year, MedicalBrief reported last week that it is very expensive in this country, and not easily available.
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Covid drug Paxlovid now approved for use in SA
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