Associated treatment emergent adverse events (TEAE) correlating with antiseizure medication (ASM) drug load is a controversial topic. Previous studies used daily defined dosage (DDD) to measure drug load. We aim to assess if drug corrected for weight as well as ASM plasma levels were associated with TEAE.
We analysed clinical visits of a trial on therapeutic drug monitoring. TEAE, treatment and its changes as well as ASM plasma levels were recorded at each visit. Each medication level was stratified according to its position in relation to its proposed reference range (below, in lower half, upper half or above).
We analyzed 424 visits (151 participants). TEAE were reported at 84 (19.7%) visits. There was no significant difference when comparing visits with TEAE with those without TEAE in terms of ASM drug load (calculated with DDD), corrected for body weight, their changes since the last visit, as well as summed plasma levels compared to reference ranges.
Drug load seems not to be a major determinant of TEAE as recording during routine visits, even when accounting thoroughly for the patient’s exposure to the treatment. The use of questionnaires and neuropsychometric tests are likely to assess more accurately the potential consequences of drug loads.