Not So Fast! There Are Some Complicating Factors...

 

"[Like any other medication, Paxlovid carries] some risks."

"Paxlovid is a prescription medication. It has the potential to interact with a number of other commonly used drugs in ways that can decrease drug effectiveness or in some cases, cause potentially serious effects."

"As with any prescription medication, patients need to discuss the risks and benefits of treatment with the health care provider who is aware of their health conditions."

Dr. Supriya Sharma, Chief Medical Adviser, Health Canada

 

"People are assuming that if they get COVID and they have risk factors, they can just get this prescription. But it's not that simple."

"It is a great thing to have in the tool box, but won't make a huge dent."

Dr.Lynora Saxinger, infectious-disease specialist, University of Alberta

Pfizer's Paxlovid   CBC

"We know that the unvaccinated are at higher risk of getting severe outcomes and getting hospitalized and ending up in the ICU. So this is the evidence, and we’re following that evidence,"

"As health care providers, you don’t pick and choose which patients you have coming into the hospital and getting treated. And so I think this approach [making the prescription drug Paxlovid available as an oral medication against COVID] ensures that we are prioritizing treatments for those most in need."

Canada's Chief Public Health Officer Dr. Teresa Tam

The U.S. Food and Drug Administration (FDA) product monograph for Pfizer's oral COVID medication lists over a hundred other drugs, many of them commonly prescribed, that should not be taken with the COVID pills. Alternately under certain circumstances, continued with under a doctor's direction and carefully monitored. Ironically, the patients for whom Paxlovid is most likely to be prescribed, the elderly and the immuno-compromised who have among other illnesses, heart problems and high blood pressure, take medications to ease symptoms for which Paxlovid can be counterindicated.

Pfizer's final trials with its COVID pill was given a high success rating of 90 percent in cutting hospitalizations in high risk patients who were given the drug in the early detected stage of their illness. A drug that is easily administered, and although under a medical supervisor's direction, can be taken at home for the five-day treatment that it entails. In Canada, the federal government ordered a million courses of the drug. And it is provided free of charge to the patient, by prescription.

In many ways this new drug appears to answer some very large asks of a COVID medication. On the other hand there is the downside involved with its use whereby a booster ingredient added to the drug for greater efficacy has the potential to  react dangerously with quite a few commonly used medications. Increasing, for example, the potency of blood thinners, heart-arrhythmia therapies, epilepsy drugs and a long list of others. 

People most at risk of serious COVID infection are the very patients targeted for the new pill['s use. Their age and other health issues make them likely candidates for the very drugs that the new Pfizer pill is contraindicated for. "It has a utility, it has a use. (But) I certainly would not call it a game-changer" noted Dr. Gerald Evens,  head, infectious diseases division of Queen's University medical school.

The issue winds around one part of the new medication, a drug called ritonavir, which inhibits enzymes that metabolize drugs; and it leaves more of the active ingredient, nirmatrlvir to enable it to work more efficaciously against the virus. The booster, ritonavir has the very same purpose impacting on a range of other drugs to increase their potency and it can dangerously do so in some cases.

Examples abound but a few scenarios are that a patient on blood thinners could begin spontaneous bleeding in the gastrointestinal tract or brain. A patient taking pills for hypertension might see falling blood pressure so severe they pass out. "There are all kinds of ways that Paxlovid could cause serious harm", said Dr Andrew Hill, a pharmacology researcher at Liverpool University in the United Kingdom.

The FDA cautions that with certain anti-arrhythmia drugs Paxlovid could cause heart rhythm problems, so is thus contraindicated. Combining Paxlovid with cholesterol-lowering pills lovastatin and simvastatin sees the potential of leading to rhabdomyolysis, potentially a life-threatening breakdown of skeletal muscle fibres.

Doctors treating most of the patients for whom Paxlovid is recommended will have to assess patients' vulnerabilities under these circumstances. A reduction of the dose of a particular contraindicted drug may be a solution, or to hold back its use over the five-day course of Paxlovid. Doing so in other situations could be viewed as too risky for the patient. 

 

The situation presents as a challenge when elderly patients take multiple medications. The cost, just incidentally, for each course of Paxlovid is stiff, at $530.

Pfizer's Paxlovid anti-COVID pill is not the "game-changer" some people expect, an infectious diseases expert says. Photo by Handout/Pfizer/AFP via Getty Images)