The regulator had a ready answer.
“The FDA has determined that Lagevrio should only be prescribed by traditional prescribers,” the FDA wrote to Fierce Pharma in an email. “This determination is based on several factors, including the drug’s side effect profiles and the need for provider-patient consultation.”
Through a company spokesperson, Merck stopped short of addressing the disparity. But the company did stress the need for multiple COVID treatment options because of a lack of availability of certain meds in some regions. Merck also said that some COVID drugs may be inappropriate for certain individuals.
Merck also pointed to analysis of a U.S. claims database, which showed that more than 40% of adults diagnosed with COVID-19 were at risk for drug-drug interactions (DDIs) that may disqualify them for Paxlovid.
Patients 60 and older with comorbidities are especially susceptible to these DDIs, according to the report. The results were presented in May at the Society of Infectious Diseases Pharmacists annual MAD-ID meeting.
In part because of their differing efficacy, Lagevrio had a tougher road to authorization than Paxlovid did. While Merck’s drug was shown to reduce risk of hospitalization and death by only 30% in recently infected, at-risk patients in clinical testing, Pfizer’s pills cut the risk by 89%.
Lagevrio gained its thumbs-up from the FDA after an independent advisory panel voted 13-10 in favor of authorization. During their review, some experts expressed concern over the possible risk of the drug causing birth defects.
Despite questions about the treatment, Merck rang up $3.2 billion in sales of Lagevrio in the first quarter of this year and said that it anticipates between $5 billion and $5.5 billion in revenue from the pills this year.
Meanwhile, in the first quarter, Pfizer registered $1.5 billion in sales of Paxlovid. At the same time, the company said that it was still projecting a $22 billion haul from the antiviral in 2022, despite a spring sales slump.
Merck also points out that Lagevrio has sold much better internationally than in the U.S. In Japan, for example, 265,600 courses of Lagevrio had been ordered through mid-May versus 19,700 courses of Paxlovid.
The figures, however, can vary wildly depending on the country. In Korea, where Lagevrio was launched 10 weeks later than Paxlovid, the tally of courses ordered through late May was 250,200 for Pfizer’s drug versus 21,300 for Merck’s.
According to a story this week in the Wall Street Journal, doctors in many countries are prescribing Lagevrio instead of Paxlovid because of safety concerns with the Pfizer pills.
“Molnupiravir is a lot easier because it’s got a couple of minor restrictions, but it’s actually much, much, much less risk for contraindications,” Australian Medical Association VP Chris Moy, told the WSJ.