New Covid-19 Pills Carry Risks: What Patients Should Know
The first Covid-19 antiviral pills that can be taken at home are a new treatment option for infected people, but they carry safety warnings and limitations that could complicate treatment decisions for patients, doctors and pharmacists. In December, the Food and Drug Administration authorized the use of new pills from Merck & Co., with its partner Ridgeback Biotherapeutics, and Pfizer Inc., for the treatment of mild to moderate Covid-19 in people at high risk of worsening to severe disease, such as the elderly or those with certain chronic medical conditions.
Both drugs, which must be prescribed by a doctor, are five-day regimens that are supposed to be started within five days of symptom onset. The drugs work by blocking replication of the pandemic virus, and clinical trials showed they reduce the risk of hospitalization and death in people with mild to moderate Covid-19. Health officials and the drugs’ manufacturers say the benefits of the pills outweigh the risks. They could be especially useful as the Omicron coronavirus variant spreads because some other Covid-19 treatments have been shown to lose effectiveness against the variant. The new pills aren’t expected to lose effectiveness against Omicron because they target parts of the virus that don’t significantly mutate across variants.
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But not everyone infected with Covid-19 is a candidate for treatment. The Pfizer drug, Paxlovid, shouldn’t be used at the same time as certain other drugs, including common ones like the cholesterol-lowering pill simvastatin, also known by the brand Zocor. That is because a component of Paxlovid, an older boosting agent known as ritonavir, can interact with other drugs in dangerous and life-threatening ways. In some cases it may be possible to suspend use of another medication or adjust its dose during the five days that a person is supposed to take Paxlovid, doctors say.
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The second antiviral the FDA cleared recently, molnupiravir from Merck and Ridgeback, was less effective than Pfizer’s in clinical trials, reducing people’s risk of hospitalization or death by 30%. Side effects including diarrhea and dizziness were relatively rare. The FDA said adults should only take the Merck drug if they don’t have access to other treatments, or if they aren’t able to take other treatments. The FDA said adults should only take the Merck drug if they don’t have access to other treatments, or if they aren’t able to take other treatments. But the Merck drug also has safety considerations. It is authorized for adults but not children under 18 because of its potential effect on bone and cartilage growth. High doses of the drug impaired bone and cartilage growth in rat studies. The Merck drug isn’t recommended for pregnant women because of the potential for fetal harm, a safety signal seen in animal studies of the drug.
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The way Merck’s drug works also has raised concerns about its effects. It is designed to block replication of the Covid-19 coronavirus by causing genetic mutations in the virus. That has raised concerns that it could lead to variants of the virus developing in patients taking the drug, which might then escape and be transmitted to others. FDA officials said the drug reduces viral loads, and patients should self-isolate while undergoing treatment, which could mitigate this potential risk of transmitting a variant. A Merck spokeswoman said there is no evidence the drug contributed to the emergence of circulating variants.
https://www.wsj.com/articles/new-covid-19-pills-carry-risks-what-patients-should-know-11641033002 (subscription)
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