Aims: The aim of this study was to determine whether the introduction of generic formulations of antiepileptic drugs (AED) would lead to an economic saving for the public health service.
Development: The narrow therapeutic index, low solubility and non-linear pharmacokinetics of some AED mean that the ranges of bioequivalence that are authorised for generic formulations do not offer the same results regarding effectiveness and safety as those obtained by brand name drugs. This is why the potential saving stemming from the use of generic AED may be exceeded by the costs deriving from the consequences conditioned by their utilisation. These are the conclusions that can be drawn from the results of cost and effectiveness analyses conducted on two hypothetical cases of substituting (9 and 20%) treatments involving brand name carbamazepine (CBZ) with generic formulations. If a generic CBZ were introduced into the treatment of 9% of the patients taking this drug, the annual cost for one person with epilepsy would rise by 38.17 as compared to treating all these patients with brand name CBZ (marginal cost-effectiveness), and overall spending on health care in the country would grow by 2,748,000 (cost-benefit analysis). These figures rise sharply when 20% of treatments with brand name CBZ are replaced by generic formulations.
Conclusions: The bioequivalence ranges authorised for generic formulations may be inappropriate for generic AED. With certain AED, replacing a brand name product with a generic version of the same medication can have negative effects on the amount of health care resources that are consumed and, therefore, on the overall economic expenditure associated with epilepsy.