Author
Dr. Nigel SB Rawson, Ph.D.
Introduction
Some researchers have suggested that there is a link between faster drug approvals and increased numbers of serious drug safety warnings based on comparisons of data between Canada and the United States.
Objective
The purpose of this article is to review the empirical evidence on drug safety warnings issued by regulators in Canada and the United States as well as actual discontinuations of new drugs due to safety concerns, and to discuss the implications for the safety of new drugs approved in both countries.
Data
Data for this paper were obtained from a recent study (Rawson 2013), which compared the review times of 454 new therapeutic drugs approved in both Canada and the United States over a 20-year period (1992 to 2011) and their duration on the respective markets until either they acquired a serious safety warning or were discontinued for a safety reason.
Results
Over the period studied, new drug approval times were similar overall, but longer for cancer drugs in Canada compared to the United States. The probability of a new drug acquiring a serious safety warning or being discontinued for a safety reason in the 10 years after approval was higher in Canada (41.6%) than in the United States (30.7%). The number and percentage of new therapeutic drug products approved in both countries between 1992 and 2011 that were subsequently discontinued from the market for a safety reason was more or less the same. Despite the increased issuance of safety warnings by regulators in 2002-11, the actual rate of discontinuation of products from the market is somewhat smaller in 2002-11 than in 1992-2001. While Canada had only half the number of priority status (i.e. expedited approvals) drugs as the United States, the rates of discontinuation are the same in each country and lower in both countries for priority drugs than standard products.
Conclusions
Change in the regulatory behaviour of drug approval agencies offers a better explanation for the increased issuance of serious warnings than does an alleged increase in the approval of more dangerous drugs. Only an assessment of actual health outcomes experience will allow us to judge whether Health Canada’s apparent higher rate (relative to the FDA) of issuing serious drug safety warnings is appropriate or indicative of a higher sensitivity threshold for regulatory caution.
