A comparison of spontaneous adverse-event reports can identify patterns worth investigating, but cannot establish how often an event occurs among all dextroamphetamine users. A larger share of reports is not automatically a greater patient-level risk.
Wang and colleagues conducted retrospective pharmacovigilance research using WHO VigiAccess and the FDA Adverse Event Reporting System. Their VigiAccess extraction in August 2024 included 959 reports for viloxazine and 4,435 for dextroamphetamine. The study compared reported event categories and used disproportionality methods to investigate signals.
This was analysis of human spontaneous reports, not a randomized treatment trial or a prospective cohort with a known number of exposed patients. Individual reports can contain multiple reaction terms, so the count of event terms is also different from the count of reports.
The paper described differences across psychiatric, neurological, cardiac and other reporting categories. Its percentages reflect the submitted reports or reported terms used in each analysis. They do not supply the number of all treated people, their exposure duration, or the number who experienced no event.
A reporting odds ratio compares reporting patterns within a database. Even a statistically elevated signal does not, by itself, establish causation, an incidence rate or an absolute risk difference between treatments. Reporting can vary with publicity, prescribing patterns, geography, time on the market and missing clinical information.
The paper discussed newer branded formulations, but acknowledged that its ingredient-level records extended back to 1969 for dextroamphetamine and 1976 for viloxazine. Those historical records should not be attributed wholesale to a recently introduced formulation.
The authors also identified voluntary-reporting bias, incomplete data and lack of causality assessment as limitations. These issues do not make pharmacovigilance useless: it can generate hypotheses for better controlled research. They do prevent this comparison from proving that one medicine is safer for a particular patient. Reported drug involvement also differs from laboratory-confirmed exposure or demonstrated impairment at an incident.
Read our analysis of the interpretation of zero events in prospective surveillance.
Real world pharmacovigilance comparison of viloxazine and dextroamphetamine adverse reaction profiles. doi:10.1038/s41598-025-14385-2.