Simulation of respiratory tract lining fluid for in vitro dissolution study

Treatment of Idiopathic Pulmonary Fibrosis by Inhaled Silybin Dry Powder Prepared via the Nanosuspension Spray Drying Technology

Idiopathic pulmonary fibrosis (IPF) is a kind of life-threatening interstitial lung disease characterized by progressive dyspnea with accurate pathogenesis unknown. At present, heat shock protein inhibitors are gradually used to treat IPF. Silybin, a heat shock protein C-terminal inhibitor, has high safety and good application prospects. In this work, we have developed a silybin powder able to be used for inhalation administration for the treatment of IPF. Silybin powder was prepared by the spray drying method and identified using cascade impactometry, particle size, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. A rat model of bleomycin-induced IPF was used to assess the effect of inhaled silybin spray-dried powder. Lung hydroxyproline content, wet weight, histology, inflammatory factor expression, and gene expression were examined. The results showed that inhaled silybin spray-dried powder alleviated inflammation and fibrosis, limited hydroxyproline accumulation in the lungs, modulated gene expression in the development of IPF, and improved postoperative survival. The results of this study suggest that silybin spray-dried powder is an attractive candidate for the treatment of IPF.

Dissolution and Absorption of Inhaled Drug Particles in the Lungs

Dry powder inhalation therapy has been effective in treating localized lung diseases such asthma, chronic obstructive pulmonary diseases (COPD), cystic fibrosis and lung infections. In vitro characterization of dry powder formulations includes the determination of physicochemical nature and aerosol performance of powder particles. The relationship between particle properties (size, shape, surface morphology, porosity, solid state nature, and surface hydrophobicity) and aerosol performance of an inhalable dry powder formulation has been well established. However, unlike oral formulations, there is no standard dissolution method for evaluating the dissolution behavior of the inhalable dry powder particles in the lungs. This review focuses on various dissolution systems and absorption models, which have been developed to evaluate dry powder formulations. It covers a summary of airway epithelium, hurdles to developing an in vitro dissolution method for the inhaled dry powder particles, fine particle dose collection methods, various in vitro dissolution testing methods developed for dry powder particles, and models commonly used to study absorption of inhaled drug.

iBCS: 1. Principles and Framework of an Inhalation-Based Biopharmaceutics Classification System

For oral drugs, the formulator and discovery chemist have a tool available to them that can be used to navigate the risks associated with the selection and development of immediate release oral drugs and drug products. This tool is the biopharmaceutics classification system (giBCS). Unfortunately, no such classification system exists for inhaled drugs. The perspective outlined in this manuscript provides the foundational principles and framework for a classification system for inhaled drugs. The proposed classification system, an inhalation-based biopharmaceutics classification system (iBCS), is based on fundamental biopharmaceutics principles adapted to an inhalation route of administration framework. It is envisioned that a classification system for orally inhaled drugs will facilitate an understanding of the technical challenges associated with the development of new chemical entities and their associated new drug products (device and drug formulation combinations). Similar to the giBCS, the iBCS will be based on key attributes describing the drug substance (solubility and permeability) and the drug product (dose and dissolution). This manuscript provides the foundational aspects of an iBCS, including the proposed scientific principles and framework upon which such a system can be developed.