Drug interactions monitoring in epileptic clinic at Neurological Institute

Abstract

This study was a descriptive and prospective research in epileptic clinic at Neurological Institute, during ten month period from 1st June 2002 31st March 2003. The objectives were to determine the prevalence of drug interactions (DIs) of antiepileptic drugs (AEDs) and AEDs other drugs, and to compare the quality of life (QOL) before and after drug interaction monitorings (DIMs) by pharmacist. Monitoring was performed at least 1 time and more than 1 month apart but no longer than 3 months. There were 312 subjects enrolled in this study. Incidence of DIs was 27.88% (87 cases), which can be devided into 2 categories; 26.28% (82 cases) of possible DIs (PDIs) and 1.60% (5 cases) of actual DIs (ADIs). Three hundreds and twelve prescriptions from 312 cases were enrolled to identify drug groups which favorable prescribed, the most favorable AED was phenobarbital (203 cases, 65.06%), phenytoin (196 cases, 62.82%) and carbamazepine (130 cases, 41.67%), respectively. Drugs which favorable prescribed with AEDs were folic acid (199 cases, 63.78%), benzodiazepines, vitamin & minerals and tricyclic antidepressants, respectively. The clinical importance interaction between AEDs, VPA and LTG, was not found in this clinic. In cases presented with PDIs, classified into 32 DDIs of pharmacokinetics interactions, the mechanism was metabolic processes (90.63%). The severity of DIs of 58.42% was moderate and 42.57% was minor and no severe case. Pharmacodynamic PDIs were classified into 58 of DDIs, the most common mechanism was additive interaction and combined toxicity (51.72%). The severity of all PDIs were minor. This study found that ADIs occurred during metabolic stage, pharmacokinetic interactions. Medications prescribed in cases of ADIs were estrogens and warfarin. Patients 138 from 312 cases (44.23%) were enrolled for QOL assessment. In aspect of adverse events of AEDs and general health, PDIs group showed an improvement of QOLʼs score after DIMs by pharmacist (p = 0.864 and 0.045). But in ADIs group found that general health was declined significantly. In aspect of psychosocial, improved scores in 13 domains were observed in PDIs groups and 12 domains in ADIs, respectively.