Auswirkung der Einführung eines Topiramat-Generikums auf die Kosten des Gesundheitssystems in Deutschland

The purpose of the study was to forecast the economic impact of the introduction of a generic analogue of the antiepileptic drug (AED) topiramate in Germany. First, health care costs for a cohort of Canadian epilepsy patients were calculated during brand versus generic use of topiramate. Over a period of 2.6 years on average, 1164 patients (mean age: 39.8 years, 61.7 % female) were observed. Subsequently, the results were reanalysed, taking into account the present situation in Germany. Several policy mechanisms were enacted, essentially consisting of various forms of price, volume and / or profit controls. Data were adjusted to the varying use of services, patient characteristics, medication costs, policy framework and structure of the health-car system. The forecast was based also on generic data available from 3 other AEDs (gabapentin, lamotrigine, oxcarbazepine) and one oral antipsychotic for which a generic (risperidone) recently became available. Health data on sales between 1998 and 2008 were used. With complete generic substitution, system-wide costs for topiramate users would rise by 23.2 % one year after generic introduction. Specifically, increases in non-topiramate health-care costs would more than offset the savings for topiramate costs, due to other AED or non-AED prescriptions and greater utilisation of health-care services. Moreover, based on past experience, introducing a generic product results in an increase in the overall market and therefore the costs continue to rise. The use of generic lamotrigine in Canada was associated with increased overall medical costs compared to brand use, thus contradicting the conventional assumption that generic substitution always provides cost savings.