In late December 2021, FDA issued a EUA for the Pfizer and Merck oral antiviral medications to manage patients with mild to moderate COVID-19, having a risk of progression to severe infection. However, both the medications are not authorized for pre-or post-exposure prophylaxis, and should not be used to treat patients with severe COVID-19, including those who are hospitalized.

Both medications need to be initiated as soon as possible after a COVID-19 diagnosis and within 5 days of symptom onset. Pfizer’s Paxlovid should be taken as two nirmatrelvir 150 mg tablets and one 100 mg ritonavir tablet by mouth, twice daily, for 5 days. Nirmatrelvir inhibits SARS-CoV-2 replication and ritonavir slows the breakdown of nirmatrelvir. Paxlovid is authorized to be used in patients 12 years and older who weigh at least 40 kg and have received a positive COVID-19 diagnosis. Dosing needs to be decreased in patients with compromised renal function and there are drug-drug interactions to avoid.

Merck’s molnupiravir comes as a 200 mg oral capsule, which is given as 4 capsules by mouth, twice daily, for 5 days. It introduces errors into the SARS-CoV-2 genetic code and is only authorized for patients 18 years and older because it may also inhibit bone and cartilage growth.

Molnupiravir is advised in patients for whom alternative COVID-19 treatment options authorized by FDA are not accessible or clinically appropriate. Similar drugs are also investigated that could have positive safety and efficacy profiles.

SOURCE-COVID-19ANTIVIRALS. APhA2022;28(2):18-19.  https://www.pharmacytoday.org/article/S1042-0991(22)00125-6/pdf