Novel potential for optimization of antitubercular therapy: Pulmonary delivery of rifampicin lipospheres

A review of formulations and preclinical studies of inhaled rifampicin for its clinical translation

Inhaled drug delivery is a promising approach to achieving high lung drug concentrations to facilitate efficient treatment of tuberculosis (TB) and to reduce the overall duration of treatment. Rifampicin is a good candidate for delivery via the pulmonary route. There have been no clinical studies yet at relevant inhaled doses despite the numerous studies investigating its formulation and preclinical properties for pulmonary delivery. This review discusses the clinical implications of pulmonary drug delivery in TB treatment, the drug delivery systems reported for pulmonary delivery of rifampicin, animal models, and the animal studies on inhaled rifampicin formulations, and the research gaps hindering the transition from preclinical development to clinical investigation. A review of reports in the literature suggested there have been minimal attempts to test inhaled formulations of rifampicin in laboratory animals at relevant high doses and there is a lack of appropriate studies in animal models. Published studies have reported testing only low doses (≤ 20 mg/kg) of rifampicin, and none of the studies has investigated the safety of inhaled rifampicin after repeated administration. Preclinical evaluations of inhaled anti-TB drugs, such as rifampicin, should include high-dose formulations in preclinical models, determined based on allometric conversions, for relevant high-dose anti-TB therapy in humans.

Inhalation Potential of Rifampicin-Loaded Novel Metal-Organic Frameworks for Improved Lung Delivery: Physicochemical Characterization, In Vitro Aerosolization and Antimycobacterial Studies

Background: The aim of the current study was to examine the potential of a rifampicin-loaded metal-organic framework (RIF@ZIF-8) for management of tuberculosis. Materials and Methods: RIF@ZIF-8 was developed using a simple, economic, and environmentally friendly ultrasonication method. Furthermore, the developed metal-organic framework (MOF) formulations were subjected to physicochemical characterization analyses such as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffractometry, thermogravimetric analysis, field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and UV spectroscopy. In addition, in vitro release, powder flow characterization, in vitro lung deposition, and efficacy studies against the Mycobacterium tuberculosis (MTB) H37Rv strain were performed. Results: Physicochemical characterization confirms its spherical shape and drug loading, whereas in vitro release analysis shows 80.5 ± 5.5% release of the drug from the loaded formulation within 48 hours. Furthermore, powder flow properties suggested that the nature of MOFs is free flowing. Additionally, in vitro lung deposition studies indicated an emission fraction of 88.02 ± 10.23% for the emitted dose and circa 21% fine particle fraction. The mass median aerodynamic diameter and geometric standard deviation were found to be 4.42 ± 0.07 μm and 1.55 ± 01 μm, respectively. The in vitro aerosol performance study demonstrated higher deposition at stages 3, 4, and 5 of the cascade impactors, which simulate deep lung delivery in terms of the trachea-primary bronchus and secondary and terminal bronchi of the human lung, respectively. Moreover, RIF@ZIF-8 exhibited improved antimycobacterial activity (0.0125 mg/mL) vis-à-vis an unformulated drug (0.025 mg/mL) against the MTB H37Rv strain, using the BACTEC 460TB system. Conclusions: Therefore, MOFs could be promising nanocarriers for targeting lungs and overcoming the hepatotoxicity associated with antituberculosis drugs requiring inhalation administration.

Inhalation potential of N-Acetylcysteine loaded PLGA nanoparticles for the management of tuberculosis: In vitro lung deposition and efficacy studies

Several studies have stated that mucus is a critical hurdle for drug delivery to the mucosal tissues. As a result, Polymeric nanoparticles that can overcome mucus barriers are gaining popularity for controlled drug delivery into intra-macrophages to attain high intracellular drug concentration. The present study was aimed to fabricate inhalable N-acetylcysteine (NAC) modified PLGA mucus penetrating particles using the double emulsion method (w/o/w) for target delivery to alveolar macrophages and minimize the dose-related adverse effects, efficiently encapsulate hydrophilic drug, sustain the release profile and prolong the retention time for the management of tuberculosis. Among the numerous formulations, the drug/polymer ratio of 1:10 with 0.50% PVA concentration and sonication time for 2 ​min ​s was chosen for further research. The formulated nanoparticles had a mean particle size of 307.50 ​± ​9.54 ​nm, PDI was 0.136 ​± ​0.02, zeta potential about -11.3 ​± ​0.4 ​mV, decent entrapment efficiency (55.46 ​± ​2.40%), drug loading (9.05 ​± ​0.22%), and excellent flowability. FTIR confirmed that NAC and PLGA were compatible with each other. SEM graphs elucidated that the nanoparticles were spherically shaped with a slightly rough surface whereas TEM analysis ensured the nanometer size nanoparticles and coating of lipid over NPs surface. PXRD spectrum concluded the transformation of the drug from crystalline to amorphous state in the formulation. In vitro release pattern was biphasic started with burst release (64.67 ​± ​1.53% within 12hrs) followed by sustained release over 48hrs thus enabling the prolonged replenishing of NAC. In vitro lung deposition study pronounced that coated NAC-PLGA-MPPs showed favorable results in terms of emitted dose (86.67 ​± ​2.52%), MMAD value (2.57 ​± ​0.12 ​μm), GSD value (1.55 ​± ​0.11 ​μm), and FPF of 62.67 ​± ​2.08% for the deposition and targeting the lungs. Finally, in vitro efficacy studies demonstrated that NAC-PLGA-MPPs presented more prominent antibacterial activity against MTB H37Rv strain as compared to NAC. Hence, PLGA based particles could be a better strategy to deliver the NAC for lung targeting.

Application of Lipid-Based Nanocarriers for Antitubercular Drug Delivery: A Review

The antimicrobial drugs currently used for the management of tuberculosis (TB) exhibit poor bioavailability that necessitates prolonged treatment regimens and high dosing frequency to achieve optimal therapeutic outcomes. In addition, these agents cause severe adverse effects, as well as having detrimental interactions with other drugs used in the treatment of comorbid conditions such as HIV/AIDS. The challenges associated with the current TB regimens contribute to low levels of patient adherence and, consequently, the development of multidrug-resistant TB strains. This has led to the urgent need to develop newer drug delivery systems to improve the treatment of TB. Targeted drug delivery systems provide higher drug concentrations at the infection site, thus leading to reduced incidences of adverse effects. Lipid-based nanocarriers have proven to be effective in improving the solubility and bioavailability of antimicrobials whilst decreasing the incidence of adverse effects through targeted delivery. The potential application of lipid-based carriers such as liposomes, niosomes, solid lipid nanoparticles, nanostructured lipid carriers, nano and microemulsions, and self-emulsifying drug delivery systems for the treatment of TB is reviewed herein. The composition of the investigated lipid-based carriers, their characteristics, and their influence on bioavailability, toxicity, and sustained drug delivery are also discussed. Overall, lipid-based systems have shown great promise in anti-TB drug delivery applications. The summary of the reviewed data encourages future efforts to boost the translational development of lipid-based nanocarriers to improve TB therapy.

Liposomal remdesivir inhalation solution for targeted lung delivery as a novel therapeutic approach for COVID-19

Strong infectivity enables coronavirus disease 2019 (COVID-19) to rage throughout the world. Moreover, the lack of drugs with definite therapeutic effects further aggravates the spread of the pandemic. Remdesivir is one of the most promising anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) drugs. However, the limited clinical effects make its therapeutic effect controversial, which may result from the poor accumulation and activation of remdesivir in the lung. Therefore, we developed lyophilized remdesivir liposomes (Rdv-lips) which can be reconstituted as liposomal aerosol for pulmonary delivery to improve the in vivo behavior of existing remdesivir cyclodextrin conclusion compound (Rdv-cyc) injections. Liposome encapsulation endowed remdesivir with much higher solubility and better biocompatibility. The in vitro liposomal aerosol characterization demonstrated that Rdv-lips possessed a mass median aerodynamic diameter of 4.118 µm and fine particle fraction (<5 µm) higher than 50%, indicating good pulmonary delivery properties. Compared to the Rdv-cyc intravenous injection group, the Rdv-lips inhalation group displayed a nearly 100-fold increase in the remdesivir-active metabolite nucleotide triphosphate (NTP) concentration and better NTP accumulation in the lung than the Rdv-cyc inhalation group. A faster transition from remdesivir to NTP of Rdv-lips (inhalation) could also be observed due to better cell uptake. Compared to other preparations, the superiority of Rdv-lips was further evidenced by the results of an in vivo safety study, with little possibility of inducing inflammation. In conclusion, Rdv-lips for pulmonary delivery will be a potent formulation to improve the in vivo behavior of remdesivir and exert better therapeutic effects in COVID-19 treatment.

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.

Preparation and characterization of isoniazid-loaded crude soybean lecithin liposomes

Tuberculosis (TB) is a poverty related infectious disease that is rapidly giving rise to public health concerns. Lengthy drug administration and frequent adverse side-effects associated with TB treatment make anti-tubercular drugs (ATDs) good candidates for drug delivery studies. This work aimed to formulate and prepare liposomes as a cost-effective option for ATD delivery. Liposomes were prepared by film hydration using crude soybean lecithin (CL) and not pure phospholipids as in the normal practice. Cholesterol was also used (up to 25% mass ratio), and isoniazid (INH) was encapsulated as model drug using a freeze-thaw loading technique. Purified soybean lecithin (PL) was also used for comparative purposes, under the same conditions. INH-loaded liposomes were characterized for particle size, Zeta Potential (ZP), encapsulation efficiency (EE) and drug release. Physicochemical properties were investigated using thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction and Fourier transform infrared. INH-loaded CL-based liposomes showed high EE (79±2.45%). The average particle size (813.00±9.21nm) and ZP (-42.80±4.31mV) of this formulation are promising for the treatment of TB by pulmonary delivery. These findings suggest the possibility of encapsulating ATDs in liposomes made of crude soybean lecithin that is cheap and readily available.

Dry Powder Inhalers: A Focus on Advancements in Novel Drug Delivery Systems

Administration of drug molecules by inhalation route for treatment of respiratory diseases has the ability to deliver drugs, hormones, nucleic acids, steroids, proteins, and peptides, particularly to the site of action, improving the efficacy of the treatment and consequently lessening adverse effects of the treatment. Numerous inhalation delivery systems have been developed and studied to treat respiratory diseases such as asthma, COPD, and other pulmonary infections. The progress of disciplines such as biomaterials science, nanotechnology, particle engineering, molecular biology, and cell biology permits further improvement of the treatment capability. The present review analyzes modern therapeutic approaches of inhaled drugs with special emphasis on novel drug delivery system for treatment of various respiratory diseases.

Self-Assembled Nanospheres for Encapsulation and Aerosolization of Rifampicin

Rifampicin (RIF) is a benchmark drug for treatment of tuberculosis, but poor bioavailability, prolonged treatment, and pill burden have been linked to therapeutic failure and the development of multidrug resistant strains. To overcome these limitations, this study investigated a method of rifampicin nanoencapsulation and aerosol delivery using a commercial, hand-held nebulizer modified with a nitrogen stream.