Introduction: This study focused on the drug carbamazepine (CBZ), a very common antiepileptic agent, mainly used for tonic-clonic seizures, facial pain and language and even bipolar disorder. Despite the cost-effectiveness of 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 life-threatening allergic reactions and liver failure. This drop occurs in approximately 30-50% of patients prescribed CBZ. Many patients also develop resistance to CBZ. Concentrations of CBZ in patients' plasma and CNS are associated with drug efficacy and toxicity, giving rise to the study in question. This study discussed screening patients, prior to initiating CBZ treatment, for potential markers associated with CBZ efficacy and toxicity. Carbamazepine is absorbed very slowly into the body and is metabolized primarily by the hepatic genes, CYP3A4 and CYP2C8, to form carbamazepine 10-11. epoxy (CBZ-E). CBZ-E is then metabolized by EPHX1, into an inactive form and excreted in urine. The plasma level of CBZ-E, in adults, represents approximately 15 to 55% of the dose of CBZ administered. Carbamazepine also undergoes autoinduction and induces its own metabolism shortly after drug administration, resulting in decreased plasma levels [1]. Mutations in the drug transporter genes, ABCB1 and ABCC2, have also been associated with drug-resistant epilepsy and low plasma CBZ concentrations. Additionally, 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 urine. A mutation in ABCB1 was also linked to elevated CL CBZ in African Americans only. The study also associated variation in NR1I2, causing 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 and pharmacokinetic variations, future studies will need to be conducted with a larger sample size to validate the results. These findings are important because, in the future, epilepsy can be classified according to its oligogenic architecture and pharmacogenetic characteristics, thus providing the appropriate treatment to patients. [3]. This study is extremely important not only to determine the effects of genetic mutations for future treatment of patients, but also to set the stage for future studies to conduct research and have a point of comparison..