Computational evaluation of drug delivery in human respiratory tract under realistic inhalation

In recent years, pulmonary diseases have posed severe health problems because of increasing air pollution. Some of the promising drug delivery devices for administering the active pharmaceutical ingredients through the pulmonary route include a pressurized metered-dose inhaler and dry powder inhaler (DPI) for the management of respiratory illness. The drug settling (deposition) efficiency in different regions of a human respiratory tract (HRT) for different drug particle sizes is computed using the discrete phase model in the current study. A computer tomography-based realistic HRT replica is used for this purpose with different inhalation rates following a realistic inhalation profile through the DPI device. Unsteady flow analysis is carried out in a human respiratory system up to the sixth-generation bronchi. The particle force balance equation is used in the discrete-phase model to simulate the motion of drug particles in the HRT. Low, moderate, and high inhalation rates following realistic inhalation profiles are used in the present study. The particles of larger size are deposited more in the oral cavity and are deposited higher at a higher inhalation rate due to higher inertia force. It is also observed that drug particle size plays a key role in drug delivery through dry powder inhalers. It is also found that drugs should contain smaller-sized particles (called fine particles) to enable their reach in the distal bronchi