Aya Allam, M.D., Steven Lippmann, M.D. 

We know lots about the current omicron spread. So, what is going on with this new antiviral drug, branded as Paxlovid and made by Pfizer? This pharmaceutical was just approved for early-on therapeutic prescribing to patients at high risk to SARS-Cov-2 virus infection yielding a serious COVID-19 disease. It is a dual medication containing nirmatrelvir and ritonavir, two established antiviral agents. It is the first oral agent available to attenuate coronavirus illnesses and is becoming available during this recent surge of omicron virus spread. What are details?

Nirmatrelvir is an antiviral drug that blocks the activity of SARS-CoV2 protease enzymes; that interferes at the RNA level with viral protein synthesis inside human cells, therefore attenuating virus particle replication in that host. Since antiviral medicines have a short half-life, the medication regimen always includes ritonavir, a cytochrome P450 3A4 enzyme inhibitor, that thus prolongs nirmatrelvir duration and at a higher blood level. This is the mechanism by which this pharmaceutical diminishes viral loads and coronavirus illness severity, including to omicron and/or delta infections.

Available only by prescription, nirmatrelvir and ritonavir should be taken at the earliest time that a person feels sick with a then confirmed with a coronavirus infection. It might be considered for someone with or without vaccination or past COVID-19 disease. Best administered in the first three symptomatic days, and with efficacy demonstrated within the initial five days. Each dosing pack comes with two 150 mg nirmatrelvir tablets and one ritonavir pill of 100mg; this whole triple-pack of medicine is self-administered, orally twice daily. A course of treatment involves five consecutive days.

One must be at least age 12 and weigh 88 pounds to be eligible for this medication. It is not authorized for prescription to patients sick enough to require hospitalization, oxygenation, or late in the course of disease – beyond the five days period. It is not indicated for someone having significant kidney and/or liver impairment. Adverse events are rare and side effects have been mild – and commonly may include an altered sense of taste and causing diarrhea. Our government is securing large quantities of this medication at a cost of approximately $530 per five-day dosing regimen.

Nirmatrelvir and ritonavir administration has proven efficacy early in the course of disease. Research documents it best at attenuating the degree of illness, need for hospitalization, or death when prescribed at within the first three symptomatic days. At five days, investigations substantiate an 88% reduction in the risk for hospitalization or death compared to controls receiving a placebo.

While this medicine is effective to attenuate COVID-19 disease, it is only a therapeutic intervention and does not replace vaccinations, that impart preventative coverage. Clearly, this medication is especially helpful for people with comorbidities like advanced age, obesity, and numerous other risk factors. It may also prove particularly beneficial for those with immune deficiencies, individuals who are unvaccinated, or someone having already recovered from an infection.

Nirmatrelvir and ritonavir is not indicated for pre-exposure or post-exposure illness prophylaxis, only for patients already evidencing an early infection, not recommended beyond five days of illness. This offers hope to people from becoming very sick due to delta and/or omicron variants; it should be widely disseminated in this country and to the rest of the world’s population. Clinical use will determine the true value and incidence of the medication-induced side effects In the meantime, immunity self-care is protective by weight control, health maintenance, exercise, proper diet (including zinc), light exposure (for vitamin D), and sleep.