Abstract: ObjectiveUsing postmarketing pharmacovigilance data collected shortly after market authorization of lamotrigine in the UK, a study was conducted to compare the adverse event(AE) profiles of children and adults taking lamotrigine, using modified signal detection methods. MethodsData from the lamotrigine Prescription Event Monitoring(PEM) study, an observational cohort study, were stratified by age and examined using summary statistics for adverse drug reactions(ADRs), reasons for stopping treatment, deaths and follow-up information. Incidence densities of AEs in children(0-17 years) and adults(≥18 years) in the first month of treatment were compared with months 2-6 to examine whether the AE rates were different in these two periods. AE rates in children were compared with those in adults(proportional reporting ratio[PRR] and incidence rate ratios), to compare the AE profiles between these age groups. ResultsThe cohort included 2457 children and 7379 adults. Differences in the AE profiles between children and adults were observed. Rash(PRR 1.2) and Stevens-Johnson syndrome(PRR 4.5) were more commonly reported in children, and confusion more frequently in adults(PRR 6.3). In children, 33%of ADRs were reported to the Regulatory Authority compared with 44% in adults. A higher proportion of children stopped treatment due to lack of effectiveness(45% vs 38%). No deaths were attributed to lamotrigine. ConclusionThis study demonstrated that signal detection methods can be used to detect quantitative and qualitative differences in the AE profiles between the first children and adults taking a newly licensed drug.

Key words: lamotrigine, PEM study, children, adult, comparison