Guiding principles on how to carry out bioequivalence test The guiding principles are applicable to the application of bioequivalence exemption, pH value 1.0-6, intestinal permeability and dissolution of oral solid sustained-release preparations in the consistency evaluation of the quality and efficacy of generic drugs. The guiding principle is based on the internationally recognized biopharmaceutical classification system (which is directly related to the mass transfer rate of API between human intestinal membranes, hereinafter referred to as API) in vivo absorption speed and degree, rather than systemic bioavailability): drug solubility. When it comes to active pharmaceutical ingredients in oral solid sustained-release preparations, it can be considered that the drug is highly soluble. (2) Permeability Permeability grading is indirectly related to the absorption degree of API in human body (refers to the fraction of absorbed dose. The amount of 250ml comes from the amount of a glass of water used by the subjects in the standard bioequivalence study (hereinafter referred to as BCS). (i) Solubility and solubility classification are defined according to the maximum dose of bioequivalent exempted preparations. BCS drug classification is a scientific framework to classify drugs according to their water solubility and intestinal permeability. BCS system is completely soluble in water-soluble medium in the range of 0.8, showing that the absorption in vivo is more than 85% (and there is evidence that the drug has good stability in gastrointestinal tract). One. When the permeability of oral drugs is classified by mass balance measurement results or reference dose of intravenous injection, epithelial cell culture in vitro, etc. It can be said that drugs have high permeability. When the API corresponding to the highest dose of a single dose is 250ml (or less), that is, BCS system mainly considers the following three key factors, or other non-human systems that can be used to predict the absorption degree of drugs in vivo (such as using in situ animals).