What is the current situation?
Histamine H-2 (H2) blockers, including ranitidine, are used to treat gastric problems (such as reflux) and are available over the counter (OTC) and by prescription. There are 28 prescription ranitidine products available and 10 OTC. In 2019, new safety concerns about ranitidine emerged following the detection of NDMA, a potential carcinogen, in some batches of the drug. Knowing the extent and patterns of ranitidine use in Canada can help regulators estimate the risk of NDMA exposure related to this drug.
What was the aim of the study?
1. To describe exposure to ranitidine, nizatidine, famotidine and cimetidine in Canada
2. To identify patient characteristics associated with the prescription of ranitidine, nizatidine, famotidine and cimetidine in Canada.
How was the study conducted?
We used data from three Canadian Partnership for Tomorrow’s Health (CanPath) prospective cohorts: the Ontario Health Study (OHS), Quebec’s CARTaGENE (CaG) cohort and British Columbia’s Generations Project (BCGP). All were linked with electronic provincial administrative data to obtain information about medication prescribed. For OHS, only seniors could be evaluated in this way. Using these cohorts, we evaluated subjects exposed between 2009 and 2018 to one of the four histamine H2 blockers: ranitidine, nizatidine, famotidine, and cimetidine.
What did the study find?
During our study interval, 6,920 people (7.1% of eligible participants), followed for an average of 3.4 years, filled an H2 blocker prescription. Ranitidine was responsible for almost 95% of all H2 blockers dispensed in all cohorts Almost two-thirds of those using H2 blockers were female (62.2%). Subjects tended to be middle-aged and older (mean age of 57.7 years in CaG and BCGP) After filling the first prescription for an H2 blocker, the average OHS subject had 3-4 episodes of taking the drug for about 111 days at each time. In CaG and BCGP, subjects had nearly half the exposure of OHS participants (possibly related to the older age in OHS). On average, subjects did not exceed recommended daily doses in adults for ranitidine, nizatidine, or cimetidine. In summary:
- Ranitidine was responsible for almost 95% of all H2 blockers
- Overall, people were intermittent users of H2-blockers
- Doses were mostly not above recommended use
For more information, contact: Autumn Neville, Research Coordinator. [email protected]
This research is funded by CIHR-DSEN
Lead investigator: Dr. Sasha Bernatsky
Query 20-12 raised by Health Canada, Health Products and Food Branch (HPFB), Marketed Health Products Branch (MHPD), Health Products Surveillance & Epidemiology Bureau (HPSEB) and Marketed Pharmaceuticals Bureau (MPB)