Smart Pulmonary Drug Delivery: pH-sensitive Microparticulate System for Next-generation Asthma Therapeutics

Asthma is a prevalent chronic respiratory disease that is still a major concern for the global population, and it has been estimated to affect no less than 400 million people in the year 2025, mostly affecting children. Symptoms include persistent inflammation in the airways, attacks of bronchospasms, and resulting wheezing, shortness of breath, and coughing. Although there have been highly effective therapies available for patients in the form of inhalers, there have been concerns associated with the current therapies, including a lack of targeting, the need for repeated dosing, and the potential for unwanted side effects. However, to address these challenges, emerging approaches have used new delivery systems, specifically pH-sensitive microparticles. During the attack, there is a pH imbalance due to inflammation and the secretion of excess amounts of mucus. pH-responsive microparticles (1–5 μm), formulated with biocompatible materials such as chitosan, PLGA, and Eudragit, have been shown to deliver drugs to the deeper respiratory tracts and provide a sustained drug release. Furthermore, the importance of pH-responsive microparticles has been introduced in this review, wherein it has been described how these particles are capable of reducing inflammation, reducing systemic distribution, and also recovering lung functions. pH-sensitive microparticles can improve patient compliance with treatment by allowing fewer doses to be taken. This is particularly promising, especially given the worldwide burden of asthma in developing countries, where effective, precise, and simple asthma control is needed.