Single phase III drug trials are simply not big enough to detect relatively uncommon but important adverse events, which may affect large numbers of people in routine clinical use, writes Paul Dieppe and colleagues.

Furthermore, the impact of undetected adverse events is likely to be made worse if widely marketed new drugs are prescribed haphazardly and rapidly to large numbers of people. Within five months of the launch of rofecoxib, more than 42,000 patients had been prescribed the drug in England.

To prevent further similar episodes, drug companies should be legally required to make all data on serious adverse events from clinical studies available to the public immediately after completion of the research, say the authors. This will allow independent, timely, and updated systematic reviews of serious adverse events.

They also suggest phased introduction of new drugs in independent, large-scale, randomised trials before licensing, together with better postmarketing surveillance.

"Although these measures will not be popular with pharmaceutical companies, they will limit the numbers of patients exposed to unknown hazards and provide robust and unbiased evidence on adverse events before a drug is fully licensed," they conclude.

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Contact: Emma Dickinson
edickinson@bmj.com
44-207-383-6529
BMJ-British Medical Journal
14-Oct-2004