Several literature reports show that up to 30% of epileptic patients may not respond to drugrntherapy, or inadequate control of their seizures, even if there is increasing prevalence andrnincidence rates of epilepsy. But why this happens and whether it can be predicted is unknown.rnStudies show that patients who have many seizures before therapy or who have an inadequaternresponse to initial treatment with antiepileptic drugs are likely to develop refractory epilepsyrn(resistance epilepsy) of unknown origin. In this investigation, trial has been undertaken for thernprediction of the reasons of treatment failures by virtue of controlling the drug quality aspects.rnEvaluation studies provide a means of identifying quality differences between same productsrnobtained from various manufacturers. Quality analysis and evaluations are the most importantrntasks to be performed when various reports of therapy indicate problems and failures ofrntreatment.rnDifferent products of antiepileptic drugs, carbamazepine and Phenobarbital tablets werernevaluated for their in vitro quality so that a base line data was developed to quote the reasons forrnthe therapeutic failures with antiepileptic drugs from the drug quality point of view. Differentrnbrands of carbamazepine tablets and different generic products of Phenobarbital tablets marketedrnin Addis Ababa were analyzed for their identification, hardness and friability, disintegration,rndosage form uniformity (weight variation and/or content uniformity), assay (drug content), andrnin vitro dissolution profiles. In addition, values of t50% and t90% for drug release were determinedrnfor all the tablets. Weight variation test was performed for all the tablets analyzed while contentrnuniformity test was performed for two of the Phenobarbital tablets: East Africa Pharmaceuticalrnand Cadila products. With respect to identification, hardness and friability, disintegration test andrndosage form uniformity, all the tablets evaluated were in good agreement with the officialrnspecification. From the carbamazepine tablets analyzed, Tegral was found to be below the drugrnixrncontent specification, while the other brands of carbamazepine and all the Phenobarbital tabletsrnanalyzed were in accordance with their respective specifications. The dissolution tests performedrnindicated that Tegral tablet and two of the Phenobarbital tablets (East Africa Pharmaceutical andrnCadila products) did not release the required drug content within the specified time. Taver fromrnthe carbamazepine tablets and the Epharm product Phenobarbital had good dissolution profiles,rnwhile the other products showed slower dissolution rates as compared to the above two drugs.rnThe study indicated that the tablets analyzed were bioinequivalent to each other with respect tornthe in vitro quality studies as some were found to be substandard and some were unable tornrelease the required content at the specified time. Therefore, utilization of the substandard onesrnor interchange use of the bioinequivalent drug products could have contribution to treatmentrnfailures.rnThe present study will be of paramount importance provided further in vivo bioavailabilityrnevaluation of the indicated brands and generic tablet formulations are performed and correlatedrnwith the in vitro findings. Stability studies of the products should be investigated to identify ifrnpossible to quantify degraded products, continued quality surveillance of the brand and genericrntablet formulations of antiepileptic drugs from different regions of the country should bernconducted to ensure quality thereby improve clinical efficacy.