When Do We Decide That Generic and Brand-Name Drugs Are Clinically Equivalent?
Perfecting Decisions With Imperfect Evidence
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The pharmaceutical market accounts for over (US) $1 trillion dollars in revenue per year worldwide, over one third of which is generated from sales of generic drugs.1 Available evidence suggests that on average, 48% of the total volume of this market among Organization for Economic Cooperation and Development nations comprised generic medications.2 Specifically in the United States, generic drugs comprise 84% of the total volume and 28% of the total value of the pharmaceutical market. However, significant variations in the uptake and costs of generic prescriptions are observed, which are partially attributable to differences in formulary management (pharmacy benefit managers), as well as variations in regulatory, substitution, and pricing policies between countries. Although manufactures must prove that generic analogues are bioequivalent to their brand-name comparators, the validity of generic drug substitution policies and their investment returns rest on the assumption that such drugs are clinically interchangeable. The extent to which such assumptions have been tested and proven remains unclear.
See Article by Leclerc et al
It is with this context that we read with interest the article by Leclerc et al3 in this month’s issue of Circulation: Cardiovascular Quality and Outcomes. This study used the Quebec Integrated Chronic Disease Surveillance System to examine the monthly rates of adverse events among 136 177 losartan, valsartan, and candesartan users aged 66 years and beyond, during the 24 months before and 12 months after the commercialization of these generic agents. The authors tracked each patient over time and identified the date at which the patient switched from the brand-name to the generic drug (ie, defined as the commercialization date). Using interrupted time-series analyses, the authors compared monthly adverse event rates (as defined by emergency room visits and hospitalizations) between generics and brands, before and after the commercialization date.
The authors …