Rifampicin loaded chitosan nanoparticle dry powder presents an improved therapeutic approach for alveolar tuberculosis

Inhalable dry powders of rifampicin highlighting potential and drawbacks in formulation development for experimental tuberculosis aerosol therapy

Introduction: Recently, tuberculosis was reported as the leading cause of death from a single infectious agent. Standard therapy includes administration of four first-line antibiotics, i.e. rifampicin, isoniazid, ethambutol, and pyrazinamide over a period of at least 26 weeks, which in case of rifampicin oftentimes is accompanied by unwanted side effects and variable bioavailability that compromise a positive therapeutic outcome. As the main site of infection is the lungs, it is desirable to develop a therapeutic formulation to be administered via the pulmonary route.Areas covered: This work presents a literature review on studies investigating inhalable dry powder formulations including rifampicin in the context of an experimental tuberculosis therapy, with a special focus on aerosol performance.Expert opinion: It was found that formulation approaches involving different strategies and functional excipients are under investigation but as of now, no formulation has managed to leap into commercial clinical testing. Reasons for this might not primarily be associated with a lack of suitable candidates, but amongst others a lack of suitable in vitro models to assess the efficacy, therapeutic benefit, and cost-effectiveness of the candidate formulations.

Evolution of rifampicin treatment for tuberculosis

Rifampicin was discovered in 1965 and remains one of the most important drugs in tuberculosis treatment that is valued for its sterilizing activity and ability to shorten treatment. Antimicrobial activity of rifampicin was initially proved in vitro; subsequently numerous in vivo studies showed the bactericidal properties and dose-dependent effect of rifampicin. Rifampicin was first during the late 1960s to treat patients suffering from chronic drug-resistant pulmonary TB. Decades later, rifampicin continues to be studied with particular emphasis on whether higher doses could shorten the duration of treatment without increasing relapse or having adverse effects. Lesion-specific drug penetration and pharmacokinetics of rifampicin are improving our understanding of effective concentration while potentially refining drug regimen designs. Another prospective aspect of high-dose rifampicin is its potential use in treating discrepant mutation thereby eliminating the need for MDR treatment. To date, several clinical trials have shown the safety, efficacy, and tolerability of high-dose rifampicin. Currently, high-dose rifampicin has been used successfully in a routine clinical setting for the treatment of high-risk patients. However, the WHO and other relevant policy makers have not committed to implementing a controlled rollout thereof. This review describes the course that rifampicin has travelled to the present-day exploration of high-dose rifampicin treatment.

Current Advances in Chitosan Nanoparticles Based Drug Delivery and Targeting

Nanoparticles (NPs) have been found to be potential targeted and controlled release drug delivery systems. Various drugs can be loaded in the NPs to achieve targeted delivery. Chitosan NPs being biodegradable, biocompatible, less toxic and easy to prepare, are an effective and potential tool for drug delivery. Chitosan is natural biopolymer which can be easily functionalized to obtain the desired targeted results and is also approved by GRAS (Generally Recognized as Safe by the United States Food and Drug Administration [US FDA]). Various methods for preparation of chitosan NPs include, ionic cross-linking, covalent cross-linking, reverse micellar method, precipitation and emulsion-droplet coalescence method. Chitosan NPs are found to have plethora of applications in drug delivery diagnosis and other biological applications. The key applications include ocular drug delivery, per-oral delivery, pulmonary drug delivery, nasal drug delivery, mucosal drug delivery, gene delivery, buccal drug delivery, vaccine delivery, vaginal drug delivery and cancer therapy. The present review describes the formation of chitosan, synthesis of chitosan NPs and their various applications in drug delivery.

Sodium Hyaluronate Nanocomposite Respirable Microparticles to Tackle Antibiotic Resistance with Potential Application in Treatment of Mycobacterial Pulmonary Infections

Tuberculosis resistant cases have been estimated to grow every year. Besides Mycobacterium tuberculosis, other mycobacterial species are responsible for an increasing number of difficult-to-treat infections. To increase efficacy of pulmonary treatment of mycobacterial infections an inhalable antibiotic powder targeting infected alveolar macrophages (AMs) and including an efflux pump inhibitor was developed. Low molecular weight sodium hyaluronate sub-micron particles were efficiently loaded with rifampicin, isoniazid and verapamil, and transformed in highly respirable microparticles (mean volume diameter: 1 μm) by spray drying. These particles were able to regenerate their original size upon contact with aqueous environment with mechanical stirring or sonication. The in vitro drugs release profile from the powder was characterized by a slow release rate, favorable to maintain a high drug level inside AMs. In vitro antimicrobial activity and ex vivo macrophage infection assays employing susceptible and drug resistant strains were carried out. No significant differences were observed when the powder, which did not compromise the AMs viability after a five-day exposure, was compared to the same formulation without verapamil. However, both preparations achieved more than 80% reduction in bacterial viability irrespective of the drug resistance profile. This approach can be considered appropriate to treat mycobacterial respiratory infections, regardless the level of drug resistance.

In vitro Pharmacokinetic Cell Culture System that Simulates Physiologic Drug and Nanoparticle Exposure to Macrophages

PURPOSE

An in vitro dynamic pharmacokinetic (PK) cell culture system was developed to more precisely simulate physiologic nanoparticle/drug exposure.

METHODS

A dynamic PK cell culture system was developed to more closely reflect physiologic nanoparticle/drug concentrations that are changing with time. Macrophages were cultured in standard static and PK cell culture systems with rifampin (RIF; 5 μg/ml) or β-glucan, chitosan coated, poly(lactic-co-glycolic) acid (GLU-CS-PLGA) nanoparticles (RIF equivalent 5 μg/ml) for 6 h. Intracellular RIF concentrations were measured by UPLC/MS. Antimicrobial activity against M. smegmatis was tested in both PK and static systems.

RESULTS

The dynamic PK cell culture system mimics a one-compartment elimination pharmacokinetic profile to properly mimic in vivo extracellular exposure. GLU-CS-PLGA nanoparticles increased intracellular RIF concentration by 37% compared to free drug in the dynamic cell culture system. GLU-CS-PLGA nanoparticles decreased M. smegmatis colony forming units compared to free drug in the dynamic cell culture system.

CONCLUSIONS

The PK cell culture system developed herein enables more precise simulation of human PK exposure (i.e., drug dosing and drug elimination curves) based on previously obtained PK parameters.

Fabrication of Quaternized Chitosan Nanoparticles Using Tripolyphosphate/Genipin Dual Cross-Linkers as a Protein Delivery System

Various amounts of 2-((acryloyloxy)ethyl)trimethylammonium chloride were grafted onto chitosan (CS) via redox polymerization method to obtain water-soluble quaternized CS (QCS). The QCS nanoparticles loaded with bovine serum albumin (BSA) were then produced by ionic gelation with tripolyphosphate (TPP) and further covalently cross-linked with genipin. The formation of QCS nanoparticles was optimized as a function of monomer grafting yield, QCS/TPP weight ratio, and QCS/genipin weight ratio by Box-Behnken design and response surface methodology. The results showed that QCS nanoparticles prepared with a grafting yield of 50%, QCS/TPP weight ratio of 7.67, and QCS/genipin weight ratio of 60 had a particle size of 193.68 ± 44.92 nm, polydispersity of 0.232, zeta potential of +23.97 mV and BSA encapsulation efficiency of 46.37 ± 2.89%, which were close to the predicted values from mathematical models. In vitro drug release studies at pH 1.2 and pH 7.4 exhibited that the release rate of BSA was significantly decreased and the release period was significantly prolonged after QCS nanoparticles cross-linking with genipin. Therefore, QCS nanoparticles cross-linked with TPP/genipin dual cross-linkers may be a promising protein drug carrier for a prolonged and sustained delivery.

Exploring inhalable polymeric dry powders for anti-tuberculosis drug delivery

The growing interest on polymeric delivery systems for pulmonary administration of drugs anticipates a more direct and efficient treatment of diseases such as tuberculosis (TB) that uses the pulmonary route as the natural route of infection. Polymeric microparticles or nano-in-microparticles offer target delivery of drugs to the lungs and the potential to control and sustain drug release within TB infected macrophages improving the efficiency of the anti-TB treatment and reducing side effects. In a dry powder form these inhalable delivery systems have increased stability and prolonged storage time without requiring refrigeration, besides being cost-effective and patient convenient. Thus, this review aims to compile the recent innovations of inhalable polymeric dry powder systems for the delivery of anti-TB drugs exploring the methods of production, aerodynamic characterization and the efficacy of targeted drug delivery systems using in vitro and in vivo models of the disease. Advanced knowledge and promising outcomes of these systems are anticipated to simplify and revolutionize the pulmonary drug delivery and to contribute towards more effective anti-TB treatments.

Considerations in preparing for clinical studies of inhaled rifampicin to enhance tuberculosis treatment

Drug delivery via the inhaled route has advantages for treating local and systemic diseases. Pulmonary drug delivery may have potential in treating tuberculosis (TB), which is mainly localised in the lung (pulmonary tuberculosis ∼75%) while also affecting other organs (extra-pulmonary tuberculosis). Currently, rifampicin, a first-line anti-tubercular drug, is given orally and the maximum daily oral dose is the lesser of 10 mg/kg or 600 mg. Since only a small fraction of this dose is available in the lung, concentrations may frequently fail to reach bactericidal levels, and therefore, contribute to the development of multi-drug resistant pulmonary TB. Pulmonary delivery of rifampicin, either alone or in addition to the standard oral dose, has the potential to achieve a high concentration of rifampicin in the lung at a relatively low administered dose that is sufficient to kill bacteria and reduce the development of drug resistance. As yet, no clinical study in humans has reported the pharmacokinetics or the efficacy of pulmonary delivery of rifampicin for TB. This review discusses the opportunities and challenges of rifampicin delivery via the inhaled route and important considerations for future clinical studies on high dose inhaled rifampicin are illustrated.

Development of Novel Octanoyl Chitosan Nanoparticles for Improved Rifampicin Pulmonary Delivery: Optimization by Factorial Design

A novel hydrophobic chitosan derivative, octanoyl chitosan (OC) with improved organic solubility was synthesized, characterized, and employed for the preparation of rifampicin (Rif) encapsulated nanoparticle formulations for pulmonary delivery. OC was characterized to confirm acyl group substitution and cytotoxicity in A549 epithelial lung cells. OC nanoparticles were produced by the double emulsion solvent evaporation technique without cross-linking and characterized for particle size distribution, morphology, crystallinity, thermal stability, aerosol delivery, and drug release rate. OC was successfully synthesized with substitution degree of 44.05 ± 1.75%, and solubility in a range of organic solvents. Preliminary cytotoxicity studies of OC showed no effect on cell viability over a period of 24 h on A549 cell lines. OC nanoparticles were optimized using a 3² full factorial design. An optimized batch of OC nanoparticles, smooth and spherical in morphology, had mean hydrodynamic diameter of 253 ± 19.06 nm (PDI 0.323 ± 0.059) and entrapment efficiency of 64.86 ± 7.73% for rifampicin. Pulmonary deposition studies in a two-stage impinger following aerosolization of nanoparticles from a jet nebulizer gave a fine particle fraction of 43.27 ± 4.24%. In vitro release studies indicated sustained release (73.14 ± 3.17%) of rifampicin from OC nanoparticles over 72 h, with particles demonstrating physical stability over 2 months. In summary, the results confirmed the suitability of the developed systems for pulmonary delivery of drugs with excellent aerosolization properties and sustained-release characteristics.

Chitosan Nanoparticles of Gamma-Oryzanol: Formulation, Optimization, and In vivo Evaluation of Anti-hyperlipidemic Activity

The elevated blood levels of cholesterol and low-density lipoproteins result in hyperlipidemia. The available expensive prophylactic treatments are kindred with severe side effects. Therefore, we fabricated the polymeric nanoparticles of gamma-oryzanol to achieving the improved efficacy of drug. The nanoparticles were prepared by ionic gelation method and optimized using 2³ full factorial design taking drug/polymer ratio (X₁), polymer/cross linking agent ratio (X₂), and stirring speed (X₃) as independent variables. The average particle size, percentage entrapment efficiency, and in vitro drug release at 2, 12, and 24 h were selected as response parameters. The factorial batches were statistically analyzed and optimized. The optimized nanoparticles were characterized with respect to particle size (141 nm) and zeta potential (+ 6.45 mV). Results obtained with the prepared and characterized formulation showed 83% mucoadhesion towards the intestinal mucosa. The in vitro findings were complemented well by in vivo anti-hyperlipidemic activity of developed formulation carried out in Swiss albino mouse model. The in vivo studies showed improved atherogenic index, malondialdehyde, and superoxide dismutase levels in poloxamer-407-induced hyperlipidemic animals when treated with oryzanol and gamma-oryzanol nanoformulation. Based on our findings, we believe that chitosan-mediated delivery of gamma-oryzanol nanoparticles might prove better in terms of anti-hyperlipidemic therapeutics.

Biomedical Applications of Chitosan and Its Derivative Nanoparticles

Chitosan is a biodegradable natural polymer with many advantages such as nontoxicity, biocompatibility, and biodegradability. It can be applied in many fields, especially in medicine. As a delivery carrier, it has great potential and cannot be compared with other polymers. Chitosan is extremely difficult to solubilize in water, but it can be solubilized in acidic solution. Its insolubility in water is a major limitation for its use in medical applications. Chitosan derivatives can be obtained by chemical modification using such techniques as acylation, alkylation, sulfation, hydroxylation, quaternization, esterification, graft copolymerization, and etherification. Modified chitosan has chemical properties superior to unmodified chitosan. For example, nanoparticles produced from chitosan derivatives can be used to deliver drugs due to their stability and biocompatibility. This review mainly focuses on the properties of chitosan, chitosan derivatives, and the origin of chitosan-based nanoparticles. In addition, applications of chitosan-based nanoparticles in drug delivery, vaccine delivery, antimicrobial applications, and callus and tissue regeneration are also presented. In summary, nanoparticles based on chitosan have great potential for research and development of new nano vaccines and nano drugs in the future.

The Multirole of Liposomes in Therapy and Prevention of Infectious Diseases

Liposomes are closed bilayer structures spontaneously formed by hydrated phospholipids that are widely used as efficient delivery systems for drugs or antigens, due to their capability to encapsulate bioactive hydrophilic, amphipathic, and lipophilic molecules into inner water phase or within lipid leaflets. The efficacy of liposomes as drug or antigen carriers has been improved in the last years to ameliorate pharmacokinetics and capacity to release their cargo in selected target organs or cells. Moreover, different formulations and variations in liposome composition have been often proposed to include immunostimulatory molecules, ligands for specific receptors, or stimuli responsive compounds. Intriguingly, independent research has unveiled the capacity of several phospholipids to play critical roles as intracellular messengers in modulating both innate and adaptive immune responses through various mechanisms, including (i) activation of different antimicrobial enzymatic pathways, (ii) driving the fusion–fission events between endosomes with direct consequences to phagosome maturation and/or to antigen presentation pathway, and (iii) modulation of the inflammatory response. These features can be exploited by including selected bioactive phospholipids in the bilayer scaffold of liposomes. This would represent an important step forward since drug or antigen carrying liposomes could be engineered to simultaneously activate different signal transduction pathways and target specific cells or tissues to induce antigen-specific T and/or B cell response. This lipid-based host-directed strategy can provide a focused antimicrobial innate and adaptive immune response against specific pathogens and offer a novel prophylactic or therapeutic option against chronic, recurrent, or drug-resistant infections.

An Overview of Chitosan Nanoparticles and Its Application in Non-Parenteral Drug Delivery

The focus of this review is to provide an overview of the chitosan based nanoparticles for various non-parenteral applications and also to put a spotlight on current research including sustained release and mucoadhesive chitosan dosage forms. Chitosan is a biodegradable, biocompatible polymer regarded as safe for human dietary use and approved for wound dressing applications. Chitosan has been used as a carrier in polymeric nanoparticles for drug delivery through various routes of administration. Chitosan has chemical functional groups that can be modified to achieve specific goals, making it a polymer with a tremendous range of potential applications. Nanoparticles (NP) prepared with chitosan and chitosan derivatives typically possess a positive surface charge and mucoadhesive properties such that can adhere to mucus membranes and release the drug payload in a sustained release manner. Chitosan-based NP have various applications in non-parenteral drug delivery for the treatment of cancer, gastrointestinal diseases, pulmonary diseases, drug delivery to the brain and ocular infections which will be exemplified in this review. Chitosan shows low toxicity both in vitro and some in vivo models. This review explores recent research on chitosan based NP for non-parenteral drug delivery, chitosan properties, modification, toxicity, pharmacokinetics and preclinical studies.