A Review of Methods for Evaluating Particle Stability in Suspension Based Pressurized Metered Dose Inhalers.
Advances in particle engineering techniques, such as spray drying, freeze drying and supercritical fluid precipitation, have greatly enhanced the ability to control the structure, morphology, and solid state phase of inhalable sized particles (1 - 5 µm) for formulation in pressurized metered dose inhalers (pMDI). To optimize the properties of these engineered particles for formulation in hydrofluoroalkane propellants (HFA 134a / 227) it is necessary to measure both bulk and individual particle properties before, after, and during formulation. This review examines established and recently developed methods for evaluating a variety of particle properties including but not limited to size, surface and internal morphology, chemical composition, and solid state phase. Novel methods for evaluating particle physical and chemical stability directly in propellant or similar environments are also discussed.
Dexter
D
D'Sa
Faculty of Pharmacy, Pharmacy and Bank Building A15, Science Road, The University of Sydney, NSW 2006 Australia. kim.chan@sydney.edu.au.
Hak-Kim
HK
Chan
D000280:Administration, Inhalation; D000335:Aerosol Propellants / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D016503:Drug Delivery Systems; D004355:Drug Stability; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry; D036501:Metered Dose Inhalers; D010316:Particle Size; D004364:Pharmaceutical Preparations / Q000008:administration & dosage*; D013535:Suspensions; D005466:Fluorocarbons
D000335:Aerosol Propellants; D006845:Hydrocarbons, Fluorinated; D004364:Pharmaceutical Preparations; D013535:Suspensions; C094049:apaflurane; D005466:Fluorocarbons