This proposal is closely linked to the Multisource (generic) pharmaceutical products: guidelines on registration requirements to establish interchangeability (WHO Technical Report Series, No. 937, Annex 7). It aims to give national authorities sufficient background information on the various orally administered active pharmaceutical ingredients (APIs) on the WHO Model List of Essential Medicines (EML), also taking into account local usage of the API, to enable them to make an informed decision as to whether generic formulations should be subjected to in vivo bioequivalence (BE) studies or whether a biowaiver can be granted. In light of scientific work and discussion in the last decade, some of the criteria used to evaluate the API in terms of potential for a biowaiver have been revised to allow a broadened scope of application. The result is that many APIs on the EML can now be considered for the biowaiver procedure, subject to the usage and risks in the national setting...