The nebulization of alpha-1 antitrypsin (AAT) for its administration to the lung could be an interesting alternative to parenteral infusion for patients suffering from AAT genetic deficiency (AATD). In the case of protein therapeutics, the effect of the nebulization mode and rate on protein conformation and activity must be carefully considered. In this paper two types of nebulizers, i.e., a jet and a mesh vibrating system, were used to nebulize a commercial preparation of AAT for infusion and compared. The aerosolization performance, in terms of mass distribution, respirable fraction, and drug delivery efficiency, as well as the activity and aggregation state of AAT upon in vitro nebulization were investigated. The two nebulizers demonstrated equivalent aerosolization performances, but the mesh nebulizer provided a higher efficiency in the delivery of the dose. The activity of the protein was acceptably preserved by both nebulizers and no aggregation or changes in its conformation were identified. This suggests that nebulization of AAT represents a suitable administration strategy ready to be translated to the clinical practice for delivering the protein directly to the lungs in AATD patients, either as a support therapy to parenteral administration or for subjects with a precocious diagnosis, to prevent the onset of pulmonary symptoms. Graphical Abstract

Alpha-1 antitrypsin (AAT) deficiency is a genetic disorder associated with pulmonary emphysema and bronchiectasis. Its management currently consists of weekly infusions of plasma-purified human AAT, which poses several issues regarding plasma supplies, possible pathogen transmission, purification costs, and parenteral administration. Here, we investigated an alternative administration strategy for augmentation therapy by combining recombinant expression of AAT in bacteria and the production of a respirable powder by spray drying. The same formulation approach was then applied to plasma-derived AAT for comparison. Purified, active, and endotoxin-free recombinant AAT was produced at high yields and formulated using L-leucine and mannitol as excipients after identifying compromise conditions for protein activity and good aerodynamic performances. An oxygen-free atmosphere, both during formulation and powder storage, slowed down methionine-specific oxidation and AAT inactivation. This work is the first peer-reviewed report of AAT formulated as a dry powder, which could represent an alternative to current treatments.

Tablet coating with aqueous solvents represents a well-established environmentally sustainable alternative to coatings based on organic solvents. However, this practice requires a careful evaluation of potential quality issues, such as increased porosity and crack formation stemming from possible tablet components interaction with water. In this work, a preliminary study on the compression of quaternary mixtures of one model drug and three common excipients was performed to investigate the behaviour of the mixtures and the relevant components during compression. Obtained tablets were coated with a hypromellose aqueous solution followed by an enteric coating with a poly(methyl acrylate-co-methyl methacrylate-co-methacrylic acid) dispersion. At each step, tablet porosity was measured by X-Ray microcomputed tomography (XµCT). XµCT evidenced significant changes in the structure of some tablets upon coating. The mechanical characteristics of the mixture components play a crucial role in the observed porosity increase (up to 12%) after the coating. Materials with remarkable plastic densification upon compression afforded higher structural changes with swelling and cracking formation. XµCT has proven to be an essential technique for identifying morphological changes that could compromise the quality of the tablets.

Interest in drug repurposing has increased significantly in recent decades owing to its potential to accelerate the development of new medicinal products, provide new therapeutic options for patients, and generate business opportunities for pharmaceutical companies. Idiopathic pulmonary fibrosis (IPF) is defined as a chronic disease that causes an irreversible loss of lung function and premature death. Recent studies have highlighted the key role of mitochondria in lung homeostasis and the ability of thyroid hormones to promote mitochondrial activity, suggesting their potential involvment in IPF pathogenesis. In this work, we translate the findings derived from the above-mentioned researches into a dry powder drug delivery system intended to target epithelial lung cells with levothyroxine. To this end we developed nano-embedded respirable microparticles by spray drying a nanosuspension composed of levothyroxine and a hydrophilic polymer. The powder was characterized in terms of physico-chemical, toxicological and aerodynamic performance, as well as for its ability to be internalized by A549 cells and modulate their metabolic activity. The nano-embedded microparticulate drug delivery system proved to be potentially able not only to reach the deep lung but also to promote levothyroxine internalisation and mitochondria activation. Graphical abstract