Increasing the fine particle fraction of pressurised metered dose inhaler solutions with novel actuator shapes.

In this paper we demonstrate that the use of multiple orifices can improve the fine particle fraction (FPF) of pressurised metered-dose inhaler solution formulations by up to 75% when compared to a single orifice with an equivalent cross sectional area (p<0.05). While prior work has relied on metal actuator components, improvements in micro injection moulding and micro drilling now make it possible to mass produce novel orifice shapes to achieve similar FPF gains in plastic parts, with orifice diameters less than 0.

Influence of pressure transducer protrusion depth on pressure measurements of shock waves in shock tubes.

This note investigates how small changes in the protrusion depth of a pressure transducer affect the pressure measurement of a moving shock wave. Measurements are undertaken with Kistler, Kulite, and PCB sensors in flush, recessed, and protruded sensor positions. Measurements of both absolute pressure and Mach number are shown to be insensitive to sensor protrusion depth.

Drug distribution transients in solution and suspension-based pressurised metered dose inhaler sprays.

This paper presents in situ time-resolved drug mass fraction measurements in pressurised metered dose inhaler (PMDI) sprays, using a novel combination of synchrotron X-ray fluorescence and scattering. Equivalent suspension and solution formulations of ipratropium bromide in HFA-134a propellant were considered. Measurements were made both inside the expansion chamber behind the nozzle orifice, and in the first few millimeters of the spray where droplet and particle formation occur.

Revealing pMDI Spray Initial Conditions: Flashing, Atomisation and the Effect of Ethanol.

Purpose: Sprays from pressurised metered-dose inhalers are produced by a transient discharge of a multiphase mixture. Small length and short time scales have made the investigation of the governing processes difficult. Consequently, a deep understanding of the physical processes that govern atomisation and drug particle formation has been elusive.

Insights into Spray Development from Metered-Dose Inhalers Through Quantitative X-ray Radiography.

Purpose: Typical methods to study pMDI sprays employ particle sizing or visible light diagnostics, which suffer in regions of high spray density. X-ray techniques can be applied to pharmaceutical sprays to obtain information unattainable by conventional particle sizing and light-based techniques.

Methods: We present a technique for obtaining quantitative measurements of spray density in pMDI sprays.

Temporally and Spatially Resolved x-ray Fluorescence Measurements of in-situ Drug Concentration in Metered-Dose Inhaler Sprays.

Purpose: Drug concentration measurements in MDI sprays are typically performed using particle filtration or laser scattering. These techniques are ineffective in proximity to the nozzle, making it difficult to determine how factors such as nozzle design will affect the precipitation of co-solvent droplets in solution-based MDIs, and the final particle distribution.

Methods: In optical measurements, scattering from the constituents is difficult to separate.