Objective: All-case post-marketing surveillance of newly approved anticancer drugs is usually conducted on all patients in Japan. The present study investigates whether all-case post-marketing surveillance identifies fatal adverse drug reactions undetected before market entry.
Methods: We examined fatal adverse drug reactions identified via all-case post-marketing surveillance by reviewing the disclosed post-marketing surveillance results, and determined the time points in which the fatal adverse drug reactions were initially reported by reviewing drug labels. We additionally scanned emergency alerts on the Japanese regulatory authority website to assess the relationship between all-case post-marketing surveillance and regulatory action.
Results: Twenty-five all-case post-marketing surveillances were performed between January 1999 and December 2009. Eight all-case post-marketing surveillances with final results included information on all fatal cases. Of these, the median number of patients was 1287 (range: 106-4998), the median number of fatal adverse drug reactions was 14.5 (range: 4-23). Of the 111 fatal adverse drug reactions detected in the eight post-marketing surveillances, only 28 (25.0%) and 22 (19.6%) were described on the initial global and the initial Japanese drug label, respectively, and 58 (52.3%) fatal adverse drug reactions were first described in the all-case post-marketing surveillance reports. Despite this, the regulatory authority issued only four warning letters, and two of these were prompted by case reports from the all-case post-marketing surveillance.
Conclusion: All-case post-marketing surveillance of newly approved anticancer drugs in Japan was useful for the rigorous compilation of non-specific adverse drug reactions, but it rarely detected clinically significant fatal adverse drug reactions.
Keywords: adverse drug reaction reporting systems; antineoplastic agents; post-marketing drug surveillance.
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