A Priori Design of Metered Dose Inhalers
Lewis DA.
RDD Asia 2016. Volume , 2016: 187-198.
Abstract:
The versatility of ethanol-based solution hydrofluoroalkane (HFA) metered dose inhalers (MDIs) enables drugs with suitable solubility to be delivered according to predetermined characteristics, which is ideal for matching in vitro performance of existing products or delivering new active substances efficiently. Empirical equations have been described that relate the mass median aerodynamic diameter (MMAD) and fine particle fraction (FPF) of a solution MDI to the non-volatile content, metering volume, and actuator orifice geometry. The scientific basis of the approach is reviewed and exemplified using the formulation of ipratropium bromide solution MDIs. The ability to predict pharmaceutical performance of conceptual formulation and hardware combinations allows the formulator to focus upon opportunities that could improve clinical outcomes, e.g., reduced oropharyngeal drug deposition, modulation of the plume temperature to reduce patient discomfort.
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