Background: The lung is the primary entry site and target for Mycobacterium tuberculosis ; more than 80% of the cases reported worldwide are of pulmonary tuberculosis. Hence, direct delivery of anti-tubercular drugs to the lung would be beneficial in reducing both, the dose required, as well as the duration of therapy for pulmonary tuberculosis. In the present study, microsphere-based dry powder inhalation systems of the anti-tubercular drugs, rifampicin and rifabutin, were developed and evaluated, with a view to achieve localized and targeted delivery of these drugs to the lung. Methods: The drug-loaded chitosan microparticles were prepared by an ionic gelation method, followed by spray-drying to obtain respirable particles. The microparticles were evaluated for particle size and drug release. The drug-loaded microparticles were then adsorbed onto an inhalable lactose carrier and characterized for in vitro lung deposition on an Andersen Cascade Impactor (ACI) followed by in vitro uptake study in U937 human macrophage cell lines. In vivo toxicity of the developed formulations was evaluated using Sprague Dawley rats. Results: Both rifampicin and rifabutin-loaded microparticles had MMAD close to 5 μm and FPF values of 21.46% and 29.97%, respectively. In vitro release study in simulated lung fluid pH 7.4 showed sustained release for 12 hours for rifampicin microparticles and up to 96 hours for rifabutin microparticles, the release being dependent on both swelling of the polymer and solubility of the drugs in the dissolution medium. In vitro uptake studies in U937 human macrophage cell line suggested that microparticles were internalized within the macrophages. In vivo acute toxicity study of the microparticles in Sprague Dawley rats revealed no significant evidence for local adverse effects. Conclusion: Thus, spray-dried microparticles of the anti-tubercular drugs, rifampicin and rifabutin, could prove to be an improved, targeted, and efficient system for treatment of tuberculosis.

Proteins are vital for the regulation of several cellular functions, including the synthesis of structural components. The change in environmental conditions will impact conformational stability and result in aggregation. Protein aggregation involves different states of proteins, like nonnative, unfolded, and native states, which make them complex processes. The proper understanding of protein aggregation pathways involving the role of thermodynamically unfavoured lag phase, soluble protofibrils triggered polymerization through an exponential phase, and depleted free monomers owing to the saturation phase resulted in the leveling off of the polymerization process. The aggregated therapeutic proteins can induce deleterious immune responses in patients, and control of the aggregation is essential for better therapeutic protein stability and targeting with the help of stable protein structures and function. Protein–protein interactions (PPIs) are important for protein stability, aggregation rate, and solubility, while advanced computational and biophysical methods have been developed to characterize therapeutic protein aggregation better. Hence, an effective strategy for controlling, monitoring, and reproducing protein aggregation propensities of the polypeptide chains is required. An in-depth understanding of protein aggregation mechanisms, characterization, and combat strategies will counter the issues of protein aggregation. It will also reduce the cost of the product, time constraints, stable & effective product availability, and potential immunogenicity. Graphical Abstract

Highly active anti-retroviral therapy (HAART) is prescribed for HIV infection and, to a certain extent, limits the infection’s spread. However, it cannot completely eradicate the latent virus in remote and cellular reservoir areas, and due to the complex nature of the infection, the total eradication of HIV is difficult to achieve. Furthermore, monotherapy and multiple therapies are not of much help. Hence, there is a dire need for novel drug delivery strategies that may improve efficacy, decrease side effects, reduce dosing frequency, and improve patient adherence to therapy. Such a novel strategy could help to target the reservoir sites and eradicate HIV from different biological sanctuaries. In the current review, we have described HIV pathogenesis, the mechanism of HIV replication, and different biological reservoir sites to better understand the underlying mechanisms of HIV spread. Further, the review deliberates on the challenges faced by the current conventional drug delivery systems and introduces some novel drug delivery strategies that have been explored to overcome conventional drug delivery limitations. In addition, the review also summarizes several nanotechnology-based approaches that are being explored to resolve the challenges of HIV treatment by the virtue of delivering a variety of anti-HIV agents, either as combination therapies or by actively targeting HIV reservoir sites.