President Biden touted a new anti-Covid initiative in his State of the Union address Tuesday. "We're also ready with antiviral treatments. If you get Covid-19, the Pfizer pill reduces your chances of ending up in the hospital by 90%," he said. "And we're launching the 'Test to Treat' initiative so people can get tested at a pharmacy, and if they're positive, receive antiviral pills on the spot at no cost."
It's a bad idea, and the president's medical advisers should have steered him away from it.
The "Pfizer pill," Paxlovid, is actually two pills—nirmatrelvir and ritonavir. The former is the actual antiviral agent, while the second inhibits an enzyme that degrades the first, thereby increasing the concentration of nirmatrelvir in the blood. The problem is that ritonavir can cause complications when combined with a huge number of commonly prescribed drugs, especially in the patient population most in need of Covid-19 treatment: The Food and Drug Administration has made Paxlovid available under an emergency-use authorization for Covid-positive adults "who are at high risk for progression to severe Covid-19, including hospitalization or death"—the elderly and patients with comorbidities.
The FDA's Paxlovid fact sheet lists six pages of "Established and Other Potentially Significant Drug Interactions." While patients could probably do without or reduce the dose of their statin or antigout medicine during the five-day course of Paxlovid, that's not the case for many other drugs on the drug interactions list. They include blood thinners and drugs that prevent cardiac arrhythmias, seizures and psychotic behavior.
That gets us back to Mr. Biden's "Test to Treat" initiative. Picture the patient at the pharmacy with a positive Covid-19 test. Has he brought a complete list of his medications? Who's going to decide whether the probability of dangerous interactions outweighs the potential benefit of Paxlovid? The pharmacy tech? The cashier? Even the pharmacist is unlikely to be capable of making that judgment.
A thoughtful announcement would have been that the National Institutes of Health was in the process of determining how nirmatrelvir could be administered alone. In the absence of ritonavir, it would need to be given more frequently—say, every six hours, instead of twice a day—but that would eliminate the drug-interaction problem. It would be an easy experiment to do, requiring only the measurement of blood levels of nirmatrelvir after different dosage schedules to find one that would achieve therapeutic levels. But like much that comes from the Biden administration, "Test to Treat" is half-baked.
Dr. Miller, a physician and molecular biologist, is a senior fellow at the Pacific Research Institute.