PLGA Carriers for Controlled Release of Levofloxacin in Anti-Tuberculosis Therapy

Levofloxacin (LFX) is a highly effective anti-tuberculosis drug with a pronounced bactericidal activity against Mycobacterium tuberculosis (Mtb). In this work, an “organic solvent-free” approach has been used for the development of polylactic-co-glycolic acid (PLGA) microparticles and scaffolds containing LFX at a therapeutically significant concentration, providing for its sustained release. To achieve the target, both nonpolar supercritical carbon dioxide and polar supercritical trifluoromethane have been used. By changing the composition, surface morphology, size, and internal structure of the polymer carriers, one can control the kinetics of the LFX release into phosphate buffered saline solutions and physiological media, providing for its acceptable burst and desirable concentration in the prolonged phase. The biocompatibility and bactericidal efficacy of PLGA/LFX carriers assessed both in vitro (against Mtb phagocytosed by macrophages) and in vivo (against inbred BALB/c mice aerogenically infected with Mtb) demonstrated their anti-tuberculosis activity comparable with that of the standard daily intragastric levofloxacin administration. These results make it possible to consider the developed compositions as a promising candidate for anti-tuberculosis control release formulations providing for the further evaluation of their activity against Mtb and their metabolism in vivo over long periods of tuberculosis infection.

Supercritical fluid (SCF)-assisted fabrication of carrier-free drugs: An eco-friendly welcome to active pharmaceutical ingredients (APIs)

Despite the success in developing various pharmaceutical formulations, most of the active pharmaceutical ingredients (APIs)/drugs, according to the Biopharmaceutics Classification System (BCS), often suffer from various intrinsic limitations of solubility and permeability, substantially hindering their bioavailability in vivo. Regardless of the fact that the availability of different particle fabrication approaches (top-down and bottom-up) towards pharmaceutical manufacturing, the supercritical fluid (SCF) technology has emerged as one of the highly effective substitutes due to the environmentally benign nature and processing convenience, as well as the economically promising character of SCFs. The exceptional features of SCFs have endowed the fabrication of various APIs either solely or in combination with the compatible supramolecular species towards achieving improved drug delivery. Operating such APIs in high-pressure conditions often results in arbitrary-sized particulate forms, ranging from micron-sized to sub-micron/nano-sized particles. Comparatively, these SCF-processed particles offer enhanced tailorable physicochemical and morphological properties (size, shape, and surface), as well as improved performance efficacy (bioavailability and therapy) over the unprocessed APIs. Although the "carrier-based" delivery is practical among diverse delivery systems, the direct fabrication of APIs into suitable particulate forms, referred to as "carrier-free" delivery, has increased attention towards improving the bioavailability and conveying a high payload of the APIs. This review gives a comprehensive emphasis on the SCF-assisted fabrication of diverse APIs towards exploring their great potential in drug delivery. Initially, we discuss various challenges of drug delivery and particle fabrication approaches. Further, different supercritical carbon dioxide (SC-CO₂)-based fabrication approaches depending on the character of SCFs are explicitly described, highlighting their advantages and suitability in processing diverse APIs. Then, we provide detailed insights on various processing factors affecting the properties and morphology of SCF-processed APIs and their pharmaceutical applications, emphasizing their performance efficacy when administered through multiple routes of administration. Finally, we summarize this compilation with exciting perspectives based on the lessons learned so far and moving forward in terms of challenges and opportunities in the scale-up and clinical translation of these drugs using this innovative technology.

Pharmaceutical Dispersion Techniques for Dissolution and Bioavailability Enhancement of Poorly Water-Soluble Drugs

Over the past decades, a large number of drugs as well as drug candidates with poor dissolution characteristics have been witnessed, which invokes great interest in enabling formulation of these active ingredients. Poorly water-soluble drugs, especially biopharmaceutical classification system (BCS) II ones, are preferably designed as oral dosage forms if the dissolution limit can be broken through. Minimizing a drug’s size is an effective means to increase its dissolution and hence the bioavailability, which can be achieved by specialized dispersion techniques. This article reviews the most commonly used dispersion techniques for pharmaceutical processing that can practically enhance the dissolution and bioavailability of poorly water-soluble drugs. Major interests focus on solid dispersion, lipid-based dispersion (nanoencapsulation), and liquisolid dispersion (drug solubilized in a non-volatile solvent and dispersed in suitable solid excipients for tableting or capsulizing), covering the formulation development, preparative technique and potential applications for oral drug delivery. Otherwise, some other techniques that can increase the dispersibility of a drug such as co-precipitation, concomitant crystallization and inclusion complexation are also discussed. Various dispersion techniques provide a productive platform for addressing the formulation challenge of poorly water-soluble drugs. Solid dispersion and liquisolid dispersion are most likely to be successful in developing oral dosage forms. Lipid-based dispersion represents a promising approach to surmounting the bioavailability of low-permeable drugs, though the technique needs to traverse the obstacle from liquid to solid transformation. Novel dispersion techniques are highly encouraged to develop for formulation of poorly water-soluble drugs.

Supercritical Fluid Technology: An Emphasis on Drug Delivery and Related Biomedical Applications

During the past few decades, supercritical fluid (SCF) has emerged as an effective alternative for many traditional pharmaceutical manufacturing processes. Operating active pharmaceutical ingredients (APIs) alone or in combination with various biodegradable polymeric carriers in high-pressure conditions provides enhanced features with respect to their physical properties such as bioavailability enhancement, is of relevance to the application of SCF in the pharmaceutical industry. Herein, recent advances in drug delivery systems manufactured using the SCF technology are reviewed. We provide a brief description of the history, principle, and various preparation methods involved in the SCF technology. Next, we aim to give a brief overview, which provides an emphasis and discussion of recent reports using supercritical carbon dioxide (SC-CO2 ) for fabrication of polymeric carriers, for applications in areas related to drug delivery, tissue engineering, bio-imaging, and other biomedical applications. We finally summarize with perspectives.

Liposomal drug products and recent advances in the synthesis of supercritical fluid-mediated liposomes

Since the pioneering research of Bangham et al. in 1965, liposomes have attracted a large amount of interest as potential carriers of various bioactive molecules for clinical applications. However, scaling-up conventional methods of liposome preparation has been proven to be challenging. Compared with conventional methods, processes that use supercritical fluid (SCF)-CO2 require a reduced amount of organic solvent, are relatively fast and simple to perform, and yield stable and more uniform liposomes. A number of studies have demonstrated that SCF-CO2 methods might be suitable for industrial-scale manufacturing of liposomes. In this review there are two topics being discussed. We provide an overview of liposomal drug products and aim to describe the physicochemical properties of liposomes prepared using various SCF methods. We review all of the available literature on SCF-CO2-based liposomes and focus on the future applications of these innovative technologies in industrial-scale liposome preparation.

State of the art and future directions in nanomedicine for tuberculosis

INTRODUCTION

Tuberculosis (TB) ranks the second leading cause of death from an infectious disease worldwide. However, treatment of TB is affected by poor patient compliance due to the requirement for daily drug administration, for lengthy periods of time, often with severe drug-induced side effects. Nanomedicines have the potential to improve treatment outcomes by providing therapies with reduced drug doses, administered less frequently, under shortened treatment durations.

AREAS COVERED

In this article, we present the pathophysiology of the disease, focusing on pulmonary TB and the characteristics of drugs used in treatment and discuss the application of nanomedicines within this scope. We also discuss new formulation approaches for TB nanomedicines and directions for future research.

EXPERT OPINION

Nanomedicines have the potential to improve TB treatment outcomes. New approaches such as nanoparticle systems able to impact the immune response of macrophages and deliver drug intracellularly, as well as the use of polymer-drug conjugates for drug delivery, are likely to play an important role in TB nanomedicines in future. However, further research is required before TB nanomedicines can be translated to the clinic.

Suitability of polymer materials for production of pulmonary microparticles using a PGSS supercritical fluid technique: preparation of microparticles using PEG, fatty acids and physical or chemicals blends of PEG and fatty acids

The production of microparticles using a supercritical carbon dioxide based PGSS technique (CriticalMix™) has been exploited to develop blended systems targeted at pulmonary delivery. Hence, PEG based polymers of different molecular weights (1000-6000 Da) were blended in situ with fatty acids (stearic, palmitic or myristic acid) or with commercially available PEG-stearates. The effect of the different thermodynamic properties of the polymers was evaluated by characterising the microparticles produced in terms of their melting temperature by conventional DSC and in the presence of high pressure CO(2) using a high pressure variable volume view cell. The microparticles produced were also assessed by SEM and particle size distribution. It is well known that as the molecular weight of the PEG chains increases, so does the viscosity of the melt and this leads to an increase in the particle size. In the paper we show that blending with myristic acid provides optimal control of particle size when the blend is sprayed from scCO(2) leading to high yields in the optimal aerodynamic size range of 2-5 μm for the deep lung delivery. The highest yield and smallest particles (~5 μm) were produced with a blend of PEG 3000 and myristic acid (1:1) whereas the batches containing palmitic acid and stearic acid showed lower yields and larger particle sizes.