Introduction: This study focused on the drug carbamazepine (CBZ), a very common antiepileptic agent, used primarily for tonic-clonic seizures, facial and tongue pain, and even bipolar disorder. Despite the cost-effectiveness of the CBZ, it also raises some areas of concern. CBZ has been shown to produce various clinical responses in patients and unpredictable adverse events such as fatal allergic reactions and liver failure. This decline occurs in approximately 30-50% of patients prescribed CBZ. Many patients also develop resistance to CBZ. CBZ concentrations in the plasma and central nervous system of patients are associated with the efficacy and toxicity of the drug, which gives rise to the current study. This study discussed screening patients, before starting CBZ therapy, for potential markers associated with CBZ efficacy and toxicity. Carbamazepine is absorbed very slowly into the body and is metabolised primarily by the hepatic genes, CYP3A4 and CYP2C8, to form carbamazepine 10-11. epoxide (CBZ-E). CBZ-E is then further metabolised, by EPHX1, to an inactive form and excreted in the urine. The plasma level of CBZ-E, in adults, is approximately 15-55% of the administered CBZ dose. Carbamazepine also undergoes autoinduction and induces its own metabolism immediately after drug administration, leading to a decrease in plasma levels [1]. Mutations in the drug transporter genes, ABCB1 and ABCC2, have also been associated with drug-resistant epilepsy and low plasma concentrations of CBZ. Furthermore, nuclear hormone receptor genes (such as NR1I2) are also associated with transcriptional activation of drug transporters and CYP genes. Due to the numerous genes associated with the pharmacokinetics (efficacy, bioavailability, and toxicity) of CBZ, interpatient ...... middle of paper ......d and excreted in the urine. A mutation in ABCB1 has also been linked to high CBZ CL only in African Americans. The study also associated a change in NR1I2, which causes activation of CYPs and transporters, with CBZ CL and the CBZ-E:CBZ ratio, meaning higher plasma concentrations of CBZ. Although this study showed associations between genetic variations and pharmacokinetics, future studies will need to be conducted with a larger sample to validate the findings. These findings are significant because, in the future, epilepsy can be classified based on its oligogenic architecture and pharmacogenetic characteristics, providing appropriate therapy for patients. [3]. This study is extremely important not only to determine the effects of genetic mutations for future patient therapy, but also to set the stage for future studies to conduct research and have a point of comparison.