Breath-holding - A Strategy in Enhancing Drug Delivery to the Lungs: A Review

After inhalation of pharmaceutical aerosols, holding of breath prior to exhalation is one of the simpler inhaler techniques when using pressurized metered-dose inhalers and dry powder inhalers. Many benefits are offered by breath holding in enhancing particle deposition, drug efficacy, reducing deposition of particles in the undesired sites and masking of hotspots. Many of the patients are not aware why this procedure is recommended by medical professionals and thus fail to get these benefits. If the breath hold step is successfully addressed, pulmonary drug delivery to the lungs will be more successful. This review addresses computer simulation studies, in particular computational fluid dynamics studies, on the influence of breath-hold in deposition patterns and behaviour of drug particles in the respiratory tract of humans. Along with the studies on breath holding reviewed here, we also briefly discuss the particle phase modelling tools like the discrete element method and discrete phase method.