Determination of carbamazepine in fingerprints: a feasibility study to evaluate adherence in epilepsy patients

Fingerprint drug concentrations can be used as a noninvasive and convenient alternative to evaluate adherence to pharmacotherapy. Fingerprints were applied over glass slides, extracted and analyzed by ultra-high performance LC–MS/MS. The assay and drug adherence questionnaires were applied to 30 epilepsy patients. The assay had linearity in the range 0.05–10 ng fingerprint , with precision of 2.16–7.9% and accuracy of 95.0–102.8%. Carbamazepine (CBZ) levels in fingerprints were stable at 45°C for 15 days. Concentrations in patient samples were 0.06–9.28 ng fingerprint . A significant difference (p = 0.003) was found between CBZ concentrations in fingerprints between patient groups divided as low and medium/high adherence. This method can potentially be applied to the identification of epilepsy patients with low adherence to CBZ pharmacotherapy.