Pharmacovigilance

Pharmacovigilance covers everything done to detect, assess, understand and prevent adverse effects after a medicine reaches patients. Its backbone is passive: clinicians, pharmacists and patients send spontaneous reports of suspected reactions, which accumulate in national and international databases. Suspicion, not proof, is the threshold for reporting, and that deliberately low bar is what makes the system sensitive enough to catch rare events.

The major collections are the FDA Adverse Event Reporting System in the United States, EudraVigilance in the European Union, the MHRA Yellow Card Scheme in the United Kingdom, and VigiBase, the World Health Organization database maintained in Uppsala, which pools reports from well over a hundred member countries. Alongside these sit active methods: prescription event monitoring, registries, and analyses of routinely collected health records.

The practical value is that a spontaneous database generates hypotheses no trial could. Trials enrol selected patients for a fixed period; real use covers pregnancy, polypharmacy, renal impairment and decades of exposure. A signal raised there is then tested where a denominator exists, in cohort or self-controlled designs, before a regulator changes a label, issues a direct healthcare professional communication, or withdraws a product.

The characteristic misuse is arithmetic. Report counts have no denominator, so they cannot yield an incidence, and reporting rates swing with media attention, product age and how easy the reporting form is. Underreporting is severe, with only a small fraction of serious reactions ever submitted. For unapproved research peptides the failure is more basic still: silence in these databases reflects the absence of a reporting channel, not a record of safe use.