Phase 4 research: what happens when the rubber meets the road?

Approval of a novel drug is oftentimes seen as the end of the development pathway. However, the appearance of rare but serious side effects in patients taking approved drugs has led to increased attention to phase 4, or postmarketing, research. Traditionally, postmarketing research relied on reports from clinicians to monitor for unexpected toxicity. However, such reporting will produce a biased assessment of risk due to underreporting of toxic …