Mathematical model of a metered-dose inhaler spray

RAMÍREZ RIGO MV.; DE CHARRAS YL; BERTÍN D

Londres

Workshop; Advanced Process Modelling Forum (APM Forum) 2020; 2020

Siemens

Pressurized metered dose inhalers (pMDIs) are drug delivery systems used for treating respiratory diseases. Droplet size and velocity are fundamental aerosol particle properties that significantly impact drug deposition efficiency in the lungs. In this context, modeling and simulation tools can assist in the study of inhalers by providing useful information to perform quantitative analyzes of their behavior.The operation of pMDIs involves turbulent and compressible flows, multiple phases and heat and mass transfer between drops and the environment. Regarding aerosol generated by MDIs, the particle size, velocity and emitted drug dose fraction depend on the propellant pressure, ambient temperature, concentration of drug and design and size of the valve. These spray properties are adequately designed to ensure the efficacy and safety of treatments during product development stages.Therefore, the simulation of pMDIs allows predicting the behavior of the aerosol plume, constituting an important tool to analyze the performance of the inhaler. A phenomenological model has been implemented in the environment gPROMS to simulate the formation of the spray in the pMDI, and the influence of the dimensions of the pMDI, environmental and propellant conditions (HFA 134a) on the generated aerosol was studied. The mathematical model consists of a system of algebraic and ordinary differential equations formed by:The Clark's model (1991), to predict the mass, density, pressure, temperature and output flow of the metering and expansion chambers.The LISA model, to predict the median aerosol generated by the inhaler.