Temporal trends in spontaneous reporting of unlabelled adverse drug reactions

Abstract

Aims: Trends in spontaneous reporting during the first years on the market were analyzed from a sample of selected drugs, with special attention to unlabelled effects.

Methods: Ten drugs were selected giving rise to approximately 100 spontaneous reports each during the first 4 years of marketing. Case reports were identified from the national pharmacovigilance database. A bibliographical score assigned at the time of reporting was used to identify unlabelled effects. Results were expressed as reporting rates.

Results: The average reporting rate peaked during the first year of marketing (54.6 per million treatment-months; s.d.: 62.8), then progressively decreased during the following years. Unlabelled effects effects represented 63% of all the spontaneous reports during the first year.

Conclusions: Unlabelled adverse effects represent a high proportion of spontaneous reports during the early years of marketing.