Background: Epilepsy is an important neurological disease, making it necessary to receive appropriate treatment. Treatment with antiepileptic drugs is the main treatment method for patients to be able to control seizures and to reduce the possible dangers that could occur to patients. Although anti-epileptic drugs are very useful for treatment, they may cause problems related to drug use, especially adverse drug reactions which are divided into 2 types: Type A reactions (Side-effects) and Type B reactions (Hypersensitivity reactions). Adverse drug reactions are important problems, which affect the abilities of the patients to control seizures and can lead to unsuccessful treatment results.
Objective: Therefore, the present study aims to examine the incidence rates of adverse drug reactions caused by taking anti-epileptic drugs, to appraise the patients’ symptoms, and to inspect the drugs that are the causes and factors, which can affect the occurrence of adverse drug reactions among epileptic patients. The data have been useful to find methods to solve problems and to discover how to deal with patients
when adverse drug reactions occur so that the findings can be apply to the future practices of patient care.
Materials and Methods: This research is a retrospective descriptive study. The data were collected from patients treated with anti-epileptic drugs at the Epilepsy Clinic at Srinagarind Hospital during the period between January 1, 2011 to December 31, 2011. The data were collected from the electronic data base of the Epilepsy Clinic and from the medical records of the outpatients at Srinagarind Hospital.
Results: There were 382 patients, who participated in the study. The most common medication which physician prescribed was Phenytoin (46.07%), followed by Sodium valproate (40.44%).The incidence of adverse drug reactions were discover in 230 cases (60.21%), including 183 cases of Type A reactions (Side effects) (47.91%) and 47 cases of Type B reactions (Hypersensitivity reactions) (12.30%). Adverse drug reactions from Type A reactions were found 221 times, and had primarily been caused by Phenytoin 109 times (49.32%) with the most common symptom being Gingival overgrowth, which was found 97 times (43.89%). Meanwhile, adverse drug reactions from Type B reactions were found 63 times and had mostly been caused by Phenytoin at 35 times (55.56%). The most common symptom was maculopapular rash, which was found 56 times (88.89%). When studying the correlation of the factors that can cause adverse drug reactions, it was revealed that when patients take more than one type of anti-epileptic drug, there is the risk of having Type A ADR and that risk is 4.25 times greater than for patients, who take only one type of anti-epileptic drug (p = 0.039). Regarding the rash caused by Phenytoin (Type B ADR), it was more commonly found in patients taking drugs which induce drug interactions at a rate of 5.39 times greater than those patients, who do not take the drugs which can induce drug interactions (p = 0.02).
Conclusion: According to the results of the present study, it was revealed that the adverse drug reactions caused by the anti-epileptic drugs taken by the epileptic patients represent important problems, whichwas commonly found. Phenytoin is the major cause of the incidences of both Type A reactions and Type B reactions. Therefore, those individuals, who are taking these medications, should be closely monitoring.

Keywords: Adverse drug reactions, Anti-epileptic drugs, Epilepsy