Abstract: Orally inhaled drug products (OIDPs) have a pivotal position and great clinical demand in the treatment of asthma and chronic obstructive pulmonary disease. The development of local generic drugs which are bioequivalent to branded drugs in efficacy and safety while with less price will not only help to solve the problem of drug accessibility, but also greatly reduce the public health burden.OIDPs are complex combinations of formulation and device, and have special drug delivery route and characteristic of local release. Thus, generic drugs of OIDPs are difficult to develop and get registration. Until now, Food and Drug Administration (FDA), European Medicines Association (EMA), Health Canada (HC) and National Medical Products Administration (NMPA) all consider that pharmacokinetics (PK) method can be used to evaluate systemic exposure (safety) in human bioequivalence (BE) study of OIDPs, but there is no consensus on its role in the evaluation of pulmonary deposition (efficacy). The possible reason lies in that the efficacy of OIDPs is determined by both the amount and the region of drug pulmonary deposition. Nevertheless, PK study is still more sensitive and economical in assessing potential differences among products, when compared with pharmacodynamics or clinical endpoint study. Here we mainly compared the domestic and international guidelines and evaluation methods of OIDPs BE study, and introduced the experimental design of PK study and its application and progress in lung deposition study. 

Key words: orally inhaled drug products, bioequivalence, pharmacokinetics, drug regulatory administration