Formulary status of drugs in Ontario after Health Canada has issued a serious safety warning: a cohort study.

Background: Drugs are approved for formulary listing based on limited knowledge of their safety. Serious safety issues are often identified after a drug is marketed.
Objective: To determine whether the listing status of drugs on the Ontario Drug Benefit (ODB) Formulary changes following the identification of safety concerns by Health Canada and whether the results of reviews by people responsible for the ODB Formulary are made public.
Methods: All new active substances (NAS) approved by Health Canada from January 1, 2002 to March 31, 2012 that subsequently had a warning issued about a serious safety concern were identified. Editions of the ODB Formulary were searched to find which of these drugs were listed on the Formulary before the safety warning was issued.
Results: A total of 263 NAS were approved of which 42 subsequently acquired one or more serious safety warnings and 15 of these were listed on the ODB Formulary before the safety warning was issued. The listing status of 14 of the 15 drugs was unchanged after the release of the safety warning. No information is available about whether the listing status of these 14 drugs was reassessed.
Conclusions: The ODB Formulary should develop a set of criteria to determine whether the listing status of drugs should be reviewed after Health Canada issues a serious safety warning. The results of any reconsiderations should made public so that prescribers and patients alike know that the ODB Formulary officials still regard the drugs as having a positive benefit to harm ratio.