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Cinically Relevant In Vitro Performance Tests for Powder Inhalers

Wei X, Byron PR.

RDD Asia 2016. Volume , 2016: 111-120.

Abstract:

Predicting drug dose in the lung and its relevant aerosol characteristics for dry powder inhalers (DPIs) is possible by conducting realistic in vitro tests using human mouth-throat (MT) models and inhalation profiles (IPs) that mimic inhaler use in the clinic. Improved in vitro–in vivo correlations (IVIVCs) of lung deposition can help drug developers better estimate a DPI’s performance under realistic clinical conditions and identify possible product- or human-related factors that may influence inhaler quality. Budelin® Novolizer® is used to illustrate how realistic in vitro tests can be used to estimate clinical performance of a DPI. Two studies were designed to characterize the (a) total lung dose in vitro (TLDin vitro) and (b) aerodynamic particle size distribution of TLDin vitro (APSDTLDin vitro). When the medium (and extremes) MT and IP were incorporated in inhaler testing, variations of TLDin vivo (ranging from 9.4% to 41.0%) could be predicted from in vitro (TLDin vitro ranging from 9.3% to 44.5%). Results for APSDTLDin vitro also indicated that the inhaler’s clinical performance could be sensitive to subject’s IPs. While the selection of MTs and IPs are yet to be standardized, product development scientists wishing to perform realistic in vitro tests may need to study possible variations in MT model and IP to fully explore the extent of variability in clinical lung deposition and the associated particle size distributions for their chosen DPI.