Development and application of an HPLC-DAD technique for human plasma concentration monitoring of perampanel and lamotrigine in drug-resistant epileptic patients.

Perampanel is a third-generation antiepileptic drug (AED), while lamotrigine is a second-generation AED. Both drugs are subject to extensive pharmacokinetic variability between different patients. Furthermore, it has been reported that perampanel and lamotrigine may be implied in pharmacokinetic drug-drug interactions with other AEDs such as carbamazepine or valproate, with consequent alterations of plasma concentrations. This emphasizes the relevance of therapeutic drug monitoring of perampanel and lamotrigine with appropriate bioanalytical methods. Herein, the development and validation of a bioanalytical techique for the simultaneous quantification of perampanel and lamotrigine in human plasma samples is described. The reported method is based on high-performance liquid chromatography coupled with diode-array detection (HPLC-DAD) and sample preparation consists of liquid-liquid extraction. Chromatographic separation of the analytes (lamotrigine and perampanel) and the internal standard (entacapone) was achieved in 12 min on a reversed-phase C18 column at 40 °C by applying a gradient elution program with a mobile phase composed of 0.1% ortho-phosphoric acid pH 2.79 (A) and acetonitrile (B) pumped at 1.0 mL/min. Perampanel was quantified at 320 nm while lamotrigine and the internal standard were monitored at 306 nm. Calibration curves were linear in the concentration range of 0.03-4.5 µg/mL (r2 = 0.9978) for perampanel and in the concentration range of 0.25-30 µg/mL (r2 = 0.9981) for lamotrigine. Overall precision did not exceed 14.3% and accuracy ranged from -6.08 to 12.66%. Some drugs potentially co-prescribed with perampanel and lamotrigine were tested and did not interfere with the retention times of the analytes and internal standard. The method was then successfully applied for the quantification of perampanel and lamotrigine in plasma samples obtained from 42 drug-resistant epileptic patients admitted to the Coimbra University Hospital Centre (CHUC.EPE, Coimbra, Portugal). In conclusion, it is a suitable method for the therapeutic drug monitoring of lamotrigine and perampanel in drug-resistant epileptic patients, as well as, for the assessment of drug-drug interactions. It can also be adopted by hospitals and laboratories, when HPLC with fluorescence and mass spectrometry detections are unavailable.