Background: Ranitidine was the most prescribed type 2 histamine receptor antagonist (H2RA) in Canada when it was recalled in 2019 because of potential carcinogenicity.
Objectives: We compared geographic and temporal patterns of in use of prescription ranitidine and three other H2RAs and estimated the population exposure to ranitidine in six Canadian provinces between 1996 and 2019.
Methods: This population-based serial cross-sectional study used prescription drug claims for H2RAs dispensed from community pharmacies in Nova Scotia (NS), Ontario (ON), Manitoba (MB), Saskatchewan (SK), Alberta (AB), and British Columbia (BC) between 1996 and 2019. Five-year pPeriod prevalence of ranitidine and other H2RAs use per 100 population were was estimated by province, age category, and sex. Exposure to ranitidine was estimated between 2015 and 2019 using Defined Daily Doses (DDDs).
Results: Subjects aged 65 years and older were dispensed 2.4 million prescriptions for ranitidine and 0.7 million prescriptions for another H2RA; younger subjects were dispensed 1.7 million prescriptions for ranitidine and 0.6 million prescriptions for another H2RA. For subjects aged 65 years and older, period prevalence of ranitidine use among women was a median of 16% (interquartile range (IQR): 13 – 27%)) higher than men; among younger subjects, prevalence was median 50% (IQR: 37 – 70%) higher among women. Among subjects aged 65 years and older, between 1996 and 1999, prevalence was higher in NS (33%) and ON (30%), and lower in the western prairie provinces (MB (18%), SK (26%), AB (17%), and lowest in BC (11%)). By the 2015-2019 period, use of ranitidine among the elderly had dropped by at least 50% in all provinces except BC. Between 2015 and 2019, we estimate that at least 142 million DDDs of prescribed ranitidine were consumed annually in six provinces.
Conclusions: These estimates of ranitidine exposure can be used for planning studies of cancer risk and identifying target populations for cancer surveillance.
