Research Program Manager University of British Columbia Victoria, Canada
Background: In March 2022, the British Columbia (BC) Ministry of Health implemented a medication monitoring program for Nirmatrelvir and ritonavir (NMVr; Paxlovid) known as PAX-F, to ensure continuity of patient care and to collect information about safety and adherence of this new and expensive drug.
Objectives: To provide evidence of patient-reported adherence to NMVr and patient-reported adverse drug events (ADE).
Methods: From February 24, 2022, to December 31, 2022, BC Pharmacists participating in the PAX-F initiative phoned patients or their caregivers 6 to 10 days after NMVr treatment initiation. Patients were asked how many days of their 5-day treatment regimen were taken, the number and severity of ADEs experienced, and how those ADEs were managed. Pharmacists recorded the information into the provincial PharmaNet database using a pre-defined coding system. We assembled summary descriptive results on adherence and ADEs. To provide information on demographics, comorbidities and drug-drug interactions, patients in the survey were linked to their other PharmaNet records, hospital discharge abstracts, emergency department encounters, physician office billings, Covid-19 PCR testing history, and Covid-19 vaccination status.
Results: A total of 10,356 follow-up phone calls were conducted by 1,962 pharmacists from the 18,035 individuals who were dispensed NMVr. Of respondents, 88% (n=9,078) reported completing their treatment. The rest reported partial completion of NMVr, except for 4% (n=419) who reported taking none. In total, 7,421 ADEs were reported of which 3.4 percent (n=255) were classified as ‘severe’ by the patient. The most common severe ADEs reported were ‘gastrointestinal’ in nature (n=39; 42%). 7% (n=9) of severe ADEs were reported to have required going to the hospital. We also analyzed the PharmaNet database for drugs known to interact with NMVr. Of 18,035 individuals dispensed NMVr, 11,050 (70%) had a previously dispensed and available supply of a drug which could potentially interact with NMVr.
Conclusions: The BC monitoring program for NMVr showed 88% patient-reported adherence and documented patient-reported adverse drug events (ADEs). Information from this kind of follow-up may be useful to drug plans in refining medication eligibility criteria.
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