A new hypothesis to investigate bioequivalence of pharmaceutical inhalation products.

BACKGROUND: This short communication reports a new hypothesis regarding bioequivalence of inhalation products which can potentially provide a reliable means to compare pharmaceutical aerosol formulations and inhalers.

METHODS: Available methods regarding the bioequivalence studies, inhaled drugs and advantages of exhaled breath condensate (EBC) samples were reviewed to develop this hypothesis.

RESULTS: It is postulated that two inhalation products providing the same drug concentrations in airway lining fluid (ALF) could be considered bioequivalent. The use of EBC tests which reflect ALF composition can be recommended as an alternative to current testing methods for consideration of bioequivalence.

CONCLUSION: The methods based on EBC analysis can potentially be applied to bioequivalence study of inhalation products and could reflect drug concentration in ALF. However, experimental studies would be necessary to support or refute this hypothesis on the novel application of EBC to bioequivalence in the future. Graphical abstract In vitro (cascade impactor) and In vivo (EBC concentration) corrolation for inhaled drugs.