Abstract

Prediction of mouth/throat deposition from pMDIs has been reported using variety of in vitro and in silico ‘‘throat’’ models. However previous in vitro methods have not provided a quantitative mapping of the induction port and have not been correlated with plume imaging techniques. The objective of this study was to develop a high-resolution induction port (HRIP) that allows quantitative determination of drug deposition within a USP induction port. It is hoped that the HRIP can allow for better understanding of pMDI plume deposition. To generate plumes with different characteristics, Rhodamine B was used as a soluble model drug (0.01% w/w), in pMDI formulations containing three different ethanol concentrations with HFA134a as the propellant. All pMDI devices had 28lL valve and an actuator with a 0.3mm orifice diameter. The HRIP mapping showed that plumes with different spray angles had different deposition patterns. For all conditions, the majority of the drug deposits on the bottom section 2–4 cm from the orifice. Above 10% ethanol composition the deposition in this zone did not increase. (EtOH: Deposition: 2.49% : 24.29%, 9.99% : 37.74%, 19.99% : 38.87%). This was similar to the plume angle observations made by video analysis. In addition, deposition of drug after the 90 degree bend decreased when ethanol concentration increased. Thus, the HRIP system demonstrated sensitivity to changes in spray angle and can quantify drug deposition as a function of geometry and other experimental factors.