Pharmacokinetic Simulation Study: Exploring the Impact of Clinical Parameters on Lamotrigine for Different Patient Populations with Implications for Liver Function Assessment and Therapeutic Drug Monitoring

Lamotrigine, widely used for managing epilepsy and bipolar disorder, carries potential side effects, including severe anticonvulsant hypersensitivity syndrome (AHS) or drug rash with eosinophilia and systemic symptoms (DRESS), which may lead to hepatotoxicity. Patients with Type 2 Diabetes (TD2) and Non-Alcoholic Fatty Liver Disease (NAFLD) are identified as more susceptible to these adverse reactions. This exploratory analysis aims to identify clinical parameters influencing lamotrigine pharmacokinetics across diverse populations, shedding light on toxicity and therapeutic drug monitoring (TDM) considerations. Starting with a retrospective analysis of 41 lamotrigine-treated patients at Hospital Santo António reveals changes or deviations from normal levels in various blood parameters and significant correlations between these parameters. Serum level changes, including creatinine, albumin, gamma-glutamyl transferase, total bilirubin, and Vitamin B12, are observed, with strong negative correlations between Vitamin B12 and creatinine. Then, we used GastroPlus and DILIsym to explore the impact of clinical parameters on lamotrigine for different patient populations. We constructed a Physiologically Based Pharmacokinetic (PBPK) model for lamotrigine in GastroPlus, based on ADMET predictions and data from the literature, to simulate the pharmacokinetic variability of lamotrigine in different populations, and we visualized the impact of increasing lamotrigine dose on its plasma concentration–time profiles (200 mg, 400 mg, 600 mg, 1200 mg) and reduced bioavailability. At higher doses, it is possible that the saturation of metabolic pathways leads to the formation of toxic metabolites or intermediates. These metabolites may exert inhibitory effects on drug-metabolizing enzymes or disrupt normal physiological processes, thereby impeding the drug’s clearance and potentially lowering its bioavailability. In DILIsym, we investigated lamotrigine’s DILI potential for individuals with diabetes and NAFLD. The results demonstrated an increased risk, emphasizing the need for careful monitoring. This study underscores the importance of understanding lamotrigine’s pharmacokinetics for tailored treatment decisions, improved outcomes, and minimized adverse reactions.