Review article: Oral, modified-release mesalazine formulations--proprietary versus generic.

Products containing mesalazine have been used in the treatment of inflammatory bowel disease for many years. Many of the oral, modified-release products are reaching the point of patent expiration, and it is expected that several new 'generic' versions will be developed. As mesalazine acts topically, the drug needs to be available at the site of inflammation to be effective. For this reason, the currently available products have been developed with individual formulations so that physicians have a choice when matching the different release profiles to the site and extent of disease. As such, the current guidelines state that oral, delayed-release mesalazine formulations are not interchangeable and should be prescribed by their proprietary (brand) name. The standard regulatory assessment process for generic or 'copy' products, using systemic bioequivalence data, does not appear to be sufficient when evaluating topically acting, oral, modified-release products. We therefore recommend that the regulatory bodies should require that new, oral mesalazine products should be assessed by a combination of dissolution, bioequivalence and (a minimum of one) adequately powered, comparative trial to determine therapeutic equivalence. Of most importance here is that the assessment of new modified-release products is sufficiently rigorous to allow patients and physicians to be confident in their use.