Therapeutic Drug Monitoring of Carbamazepine: A 20-Year Observational Study

Background: Carbamazepine (CBZ) is a first-generation anticonvulsant drug. Hence, in certain cases, therapeutic drug monitoring (TDM) supports pharmacotherapy. Methods: The presented research was based on a retrospective analysis including 710 ambulatory and hospitalized patients treated with CBZ between the years 1991 and 2011. The method used for the determination of the CBZ concentration was fluorescence polarization immunoassay (FPIA) performed using an Abbott GmbH TDx automatic analyzer, with the therapeutic range for carbamazepine being 4–12 µg/mL. Results: The therapeutic range was observed more often in patients between 3 and 17 years of age compared with the population ≥18 years of age (73.5% vs. 68.8%). The therapeutic level was exceeded less frequently in the population between 3 and 17 years of age despite them being given a significantly higher dose per kilogram of body weight than in the population ≥18 years of age (13.64 mg/kg vs. 10.43 mg/kg, p < 0.0001). Patients ≥18 years of age were statistically significantly more likely to be in the group with a suspected drug overdose (73.9% vs. 26.1%), and suicide attempts only occurred in elderly patients (100.0% vs. 0.0%, p = 0.003). Conclusion: The results of the TDM of CBZ showed that only 71% of all samples were at the therapeutic level. To ensure the maximum efficacy and safety of the therapy, it is necessary to monitor the concentration of CBZ regardless of sex and age.