The Global Bioequivalence Harmonisation Initiative (GBHI): Report of EUFEPS/AAPS fourth conference

Bioequivalence requirements for orally inhaled and nasal drug products and use of novel physiologically based biopharmaceutics modeling approaches for assessing in vivo performance

Orally inhaled and nasal drug products (OINDPs) are complex due to the interplay between the device, formulation, and patient characteristics. Establishing bioequivalence (BE) of OINDPs with reference is highly complex and require in vitro, in vivo pharmacokinetic and comparative clinical endpoint studies that are challenging to conduct. In order to increase the rate of submission and approval of generics, regulatory agencies are encouraging the use of alternative in vitro and in silico methodologies to replace complex in vivo studies. The present review attempts to summarize current understanding of alternative BE approaches for OINDPs. In vitro characterization studies required for establishing BE for OINDPs considering USFDA and EMA guidance's are detailed. In silico models such as pulmonary compartmental absorption and transit (PCAT) with emphasis on model input parameters are portrayed. Further, two detailed case studies of inhalation nebulizer and nasal spray formulations are described where PCAT models are developed for predicting BE and local concentrations. Lastly, current understanding of such BE approaches from regulatory perspectives are discussed summarizing recent regulatory workshops and through collation of USFDA product specific guidance's for almost 70 drug products. Overall, this manuscript can act as ready-to-use guide to understand alternative approaches for establishing BE for OINDPs.

A new method for investigating bioequivalence of inhaled formulations: A pilot study on salbutamol

Purpose: An efficient, cost-effective and non-invasive test is required to overcome the challenges faced in the process of bioequivalence (BE) studies of various orally inhaled drug formulations. Two different types of pressurized meter dose inhalers (MDI-1 and MDI-2) were used in this study to test the practical applicability of a previously proposed hypothesis on the BE of inhaled salbutamol formulations. Methods: Salbutamol concentration profiles of the exhaled breath condensate (EBC) samples collected from volunteers receiving two inhaled formulations were compared employing BE criteria. In addition, the aerodynamic particle size distribution of the inhalers was determined by employing next generation impactor. Salbutamol concentrations in the samples were determined using liquid and gas chromatographic methods. Results: The MDI-1 inhaler induced slightly higher EBC concentrations of salbutamol when compared with MDI-2. The geometric MDI-2/MDI-1 mean ratios (confidence intervals) were 0.937 (0.721-1.22) for maximum concentration and 0.841 (0.592-1.20) for area under the EBC-time profile, indicating a lack of BE between the two formulations. In agreement with the in vivo data, the in vitro data indicated that the fine particle dose (FPD) of MDI-1 was slightly higher than that for the MDI-2 formulation. However, the FPD differences between the two formulations were not statistically significant. Conclusion: EBC data of the present work may be considered as a reliable source for assessment of the BE studies of orally inhaled drug formulations. However, more detailed investigations employing larger sample sizes and more formulations are required to provide more evidence for the proposed method of BE assay.