Telacebec (Q203): Is there a novel effective and safe anti-tuberculosis drug on the horizon?

High prevalence and stronger emergency of various forms of drug-resistant tuberculosis (DR-TB), including the multidrug-resistant (MDR-TB) as well as extensively drug-resistant (XDR-TB) ones, caused by variously resistant Mycobacterium tuberculosis pathogens, make first-line anti-tuberculosis (anti-TB) agents therapeutically more and more ineffective. Therefore, there is an imperative to develop novel highly efficient (synthetic) agents against both drug-sensitive-TB and DR-TB. The exploration of various heterocycles as prospective core scaffolds for the discovery, development and optimization of anti-TB drugs remains an intriguing scientific endeavour. Telacebec (Q203; TCB), a molecule containing an imidazo[1,2-a]pyridine-3-carboxamide (IPA) structural motif, is considered a novel very promising anti-TB agent showing a unique mechanism of action. The compound blocks oxidative phosphorylation by inhibiting a mycobacterial respiratory chain due to interference with a specific cytochrome b subunit (QcrB) of transmembrane bc1 menaquinol-cytochrome c oxidoreductase as an essential component for transporting electrons across the membrane from menaquinol to other specific subunit, cytochrome c (QcrC). Thus, the ability of mycobacteria to synthesize adenosine-5´-triphosphate is limited and energy generating machinery is disabled. The TCB molecule effectively fights drug-susceptible, MDR as well as XDR M. tuberculosis strains. The article briefly explains a mechanism of an anti-TB action related to the compounds containing a variously substituted IPA scaffold and is focused on their fundamental structure-anti-TB activity relationships as well. Special consideration is paid to TCB indicating the importance of particular structural fragments for maintaining (or even improving) favourable pharmacodynamic, pharmacokinetic and/or toxicological properties. High lipophilicity of TCB might be regarded as one of the key physicochemical properties with positive impact on anti-TB effect of the drug. In January 2021, the TCB molecule was also involved in phase-II clinical trials focused on the treatment of Coronavirus Disease-19 caused by Severe Acute Respiratory Syndrome Coronavirus 2.

In vitro and in vivo antitubercular activity of benzothiazinone-loaded human serum albumin nanocarriers designed for inhalation

The aim of this study was to investigate the potential of human serum albumin (HSA) as a solubilising agent/drug delivery vehicle for pulmonary administration of antimycobacterial benzothiazinone (BTZ) compounds. The solubility of four novel BTZ compounds (IR 20, IF 274, FG 2, AR 112) was enhanced 2 to 140-fold by incubation with albumin (0.38-134 μg/mL). Tryptophan 213 residue quenching studies indicated moderate binding strength to Sudlow's site I. Nanoparticle manufacture achieved 37-60% encapsulation efficiency in HSA particles (169 nm, zeta potential -31 mV). Drug release was triggered by proteases with >50% released in 4 h. The antimycobacterial activity of IR 20 and FG 2 loaded in HSA nanoparticles was enhanced compared to DMSO/phosphate buffered saline (PBS) or albumin/PBS solutions in an in vitro M. tuberculosis-infected macrophage model. Intranasal instillation was used to achieve pulmonary delivery daily over 10 days to M. tuberculosis infected mice for FG2 HSA nanoparticles (0.4 mg/kg), FG 2 DMSO/saline (0.4 and 8 mg/kg) and a reference compound, BTZ043, DMSO/saline (0.4 and 8 mg/kg). A lower lung M. tuberculosis burden was apparent for all BTZ cohorts, but only significant for BTZ043 at both doses. In conclusion, mechanisms of HSA nanoparticle loading and release of BTZ compounds were demonstrated, enhanced antimycobacterial activity of the nanoparticle formulations was demonstrated in a biorelevant in vitro bioassay and the effectiveness of BTZ by pulmonary delivery in vivo was established with pilot evidence for effectiveness when delivered by HSA nanoparticles. Finally, the feasibility of developing an inhaled nanoparticle-in-microparticle powder formulation was ascertained.

Surgical treatment of tuberculous chronic constrictive pericarditis: A retrospective observational study from tertiary hospital of eastern Nepal

BACKGROUND

Tuberculosis remains an important cause of chronic constrictive pericarditis (CCP) in developing countries. It is a surgically treatable cause of diastolic heart failure. Without surgery, it is associated with high morbidity and mortality.

METHODS

We conducted a retrospective observational study of clinical presentations and perioperative outcomes of pericardiectomy in all patients operated from July 2015 to December 2018 for tuberculous CCP.

RESULTS

A total 14 patients (mean age - 38 ± 13.3 years, 10 male), underwent pericardiectomy via median sternotomy without cardiopulmonary bypass. Eleven patients (79%) had completed treatment for pulmonary tuberculosis, and three (21%) were on anti-tubercular treatment at the time of referral for surgery. Ten patients (71%) had prior hospitalisation for cardiac failure. At the time of surgery, eight patients (57%) were in New York Heart Association (NYHA) class III-IV. The median duration of symptoms before surgical intervention was 15 months (range 11-24 months). Three patients (21%) had associated cardiac cirrhosis. Twelve patients (86%) underwent total pericardiectomy. Two patients (14%) underwent partial pericardiectomy. The mean operative time was 160 ± 33.8 minutes. The mean central venous press pressure before and after surgery were 28 ± 3.9 and 10 ± 2 mmHg respectively. The mean intensive care unit (ICU) and hospital stays were 4 ± 1.5 and 10 ± 2 days respectively. There was one (7%) 30-day mortality. There were two deaths (14%) due to non-cardiac causes at 10 and 16 months respectively. The remaining 11 patients (79%) are doing well (mean follow-up- 23 months), and are in NYHA class I.

CONCLUSIONS

Tuberculosis is the most common cause of CCP in our region. Pericardiectomy provides definitive treatment to alleviate symptoms resolution and improve survival.

Postbiotics-A Step Beyond Pre- and Probiotics

As an imbalance in the intestinal microbiota can lead to the development of several diseases (e.g., type 1 diabetes, cancer, among others), the use of prebiotics, probiotics, and postbiotics to alter the gut microbiome has attracted recent interest. Postbiotics include any substance released by or produced through the metabolic activity of the microorganism, which exerts a beneficial effect on the host, directly or indirectly. As postbiotics do not contain live microorganisms, the risks associated with their intake are minimized. Here, we provided a critical review of postbiotics described in the literature, including their mechanisms of action, clinical characteristics, and potential therapeutic applications. We detailed the pleiotropic effects of postbiotics, including their immunomodulatory, anti-inflammatory, antioxidant, and anti-cancer properties. Although the use of postbiotics is an attractive strategy for altering the microbiome, further study into its efficacy and safety is warranted.

First unequivocal identification of the critical acyl radicals from the anti-tuberculosis drug isoniazid and its hydrazide analogs by complementary applications of ESR spin-trapping and HPLC/MS methods

The carbon-centered isonicotinic acyl radical of isoniazid (INH), a widely-used frontline anti-tuberculosis drug, has been considered to play a critical role in inhibiting Mycobacterium tuberculosis, but not fully identified. Here we show that this radical intermediate can be unequivocally characterized by complementary applications of ESR spin-trapping and HPLC/MS methods by employing N-tert-butyl-α-phenylnitrone (PBN) as the suitable spin-trapping agent, which can form the most stable radical adduct. More importantly, for the first time, analogous carbon-centered acyl radicals and their respective NAD⁺ adducts have also been detected and identified from its two isomers (nicotinic acid hydrazide and 2-pyridinecarbohydrazide) and benzhydrazide which are structurally-related to INH, but not by 2-chloroisonicotinohydrazide. This study represents the first unequivocal identification of the carbon-centered acyl radicals of INH and other hydrazide analogs by both ESR spin-trapping and HPLC/MS methods, which may have broad biomedical and toxicological significance for future research for more efficient hydrazide anti-tuberculosis drugs.

Synthesis of SPIONs-CNT Based Novel Nanocomposite for Effective Amperometric Sensing of First-Line Antituberculosis Drug Rifampicin

It is necessary to study the possible interactions among various chemical surfaces and analytes before applying them to biological systems. We report the synthesis of carbon nanotubes-iron oxide (SPIONs-CNT) nanocomposite material by using lecithin stabilized superparamagnetic iron oxide nanoparticles (SPIONs) obtained by facile hydrothermal technique. Various characterizations of the obtained nanocomposite were carried out and electrochemical studies were performed further to study the interaction capabilities of the nanocomposite with anti-TB drug Rifampicin. Obtained results by cyclic voltammetric studies of SPIONs-CNT nanocomposite with limit of detection (LOD) of 1.178 μM showed the enhanced electrochemical sensitivity and selectivity of anti-tuberculosis (anti-TB) drug Rifampicin (RIF).

Predicting Interactions between Rifampin and Antihypertensive Drugs Using the Biopharmaceutics Drug Disposition Classification System

STUDY OBJECTIVE

Lack of blood pressure control is often seen in hypertensive patients concomitantly taking antituberculosis medications due to the complex drug-drug interactions between rifampin and antihypertensive drugs. Therefore, it is of clinical importance to understand the underlying mechanisms of these interactions to help formulate recommendations on the use of antihypertensive drugs in patients taking these medications concomitantly. Our objective was to assess the reliability of the Biopharmaceutics Drug Disposition Classification System (BDDCS) to predict potential interactions between rifampin and antihypertensive drugs and thus provide recommendations on the choice of antihypertensive drugs in patients receiving rifampin.

DESIGN

Evidence-based in vitro and in vivo predictions of drug-drug interactions.

MEASUREMENTS AND MAIN RESULTS

We systematically evaluated interactions between rifampin and antihypertensive drugs using the theory of the BDDCS, taking into consideration the role of drug transporters and metabolic enzymes involved in these interactions. We provide recommendations on the selection of antihypertensive drugs for patients with tuberculosis. Antihypertensive drugs approved by the U.S. Food and Drug Administration and the China National Medical Products Administration were included in this study. The drugs were classified into four categories under the BDDCS classification. Detailed information on cytochrome P450 (CYP) enzymes and drug transporters for each antihypertensive drug was searched in PubMed and other electronic databases. This information was combined with the effects of rifampin on CYP enzymes and drug transporters, and the direction and relative extent of the potential interactions between rifampin and antihypertensive drugs were predicted. Recommendations were then made using the theory of BDDCS. A thorough systematic literature review was performed, and data from all published human studies and case reports were summarized for the validation of our predictions. Interventional and observational studies published in PubMed and two Chinese databases (CNKI and WanFang) through December 16, 2019, were included, and data were extracted for validation of the predictions. Using the BDDCS theory, class 3 active drugs were predicted to exhibit minimal interactions with rifampin. On reviewing case reports and pre-post studies, the predictions we made were found to be reliable. When antituberculosis medications that include rifampin are started in patients with hypertension, it is recommended that the use of calcium channel blockers and classes 1 and 2 β-blockers be avoided. Angiotensin-converting enzyme inhibitors, olmesartan, class 3 β-blockers, spironolactone, and hydrochlorothiazide would be preferable because clinically relevant interactions would not be expected.

CONCLUSION

Application of the BDDCS to predict interactions between rifampin and antihypertensive drugs for patients with both tuberculosis and hypertension was found to be reliable. It should be noted, however, that based on the CYP enzyme and drug transporter information we reviewed, the mechanisms of all of the interactions could not be elucidated, and the predictions are only based on theory. The real effects of rifampin on antihypertensive drugs need to be further observed. More studies in both animals and humans are needed in the future.

Mycobacterium tuberculosis thymidylate synthase (ThyX) is a target for plumbagin, a natural product with antimycobacterial activity

Plumbagin derived from the plant Plumbago indica, known as Chitrak in India, is an example of a medicinal compound used traditionally to cure a variety of ailments. Previous reports have indicated that it can inhibit the growth of Mycobacterium tuberculosis (Mtb), the causative agent of the deadly disease TB. In this investigation, we provide an insight into its mode of action. We show here that a significant mycobacterial target that is inhibited by plumbagin is the enzyme ThyX, a form of thymidylate synthase, that is responsible for the synthesis of dTMP from dUMP in various bacterial pathogens, including Mtb. Using a purified preparation of the recombinant version of Mtb ThyX, we demonstrate that plumbagin, a 2,4 napthoquinone, but not lawsone, a structurally related medicinal compound, inhibits its activity in vitro. We also show that the intracellular [dTTP]/[dATP] ratio in Mycobacterium smegmatis (Msm) cells decrease upon treatment with plumbagin, and this, in turn, leads to cell death. Such a conclusion is supported by the observation that over-expression of thyx in the plumbagin treated Msm cells leads to the restoration of viability. The results of our investigation indicate that plumbagin kills mycobacterial cells primarily by targeting ThyX, a vital enzyme required for their survival.

Isoniazid-resistant tuberculosis: A problem we can no longer ignore

Giorgia Sulis and Madhukar Pai discuss the global distribution, and approaches to diagnosis and treatment, of isoniazid-resistant tuberculosis.

PURL: A better approach to preventing active TB?

Nine months of isoniazid prevents active TB in those with latent disease. But is there a shorter, less toxic option?

Diagnostic chemoresistant mycobacterium tuberculosis in the ternopil region of Ukraine

OBJECTIVE

The aim: To analyze the changes in indicators of tuberculosis mycobacteria sensitivity to anti-mycobacterial drugs over the past nine years in Ternopol region (Ukraine) and to develop recommendations for the use of drug combinations in this region.

PATIENTS AND METHODS

Materials and methods: The medical examinations were carried out in the Clinical and Diagnostic Laboratory of Ternopil Regional Tuberculosis Hospital during 2007-2017. Sensitivity analysis was carried out on a solid Löwenstein-Jensen medium and in liquid Meedlebrook medium using automatic bacteriological BACTEC 1443 tests with addition to the media of first line anti-TB drugs.

RESULTS

Results: The sensitivity of Mycobacterium tuberculosis to anti-TB drugs has decreased in 2017 comparing to 2007, both among new cases and relapses of the disease.During this period in newly diagnosed patients the number of M. tuberculosis sensitive to first-line anti-TB drugs has decreased by 6.1%.

CONCLUSION

Conclusions: Considering the increase in multi-resistant pathogens in newly diagnosed and relapsed of tuberculosis cases, it is necessary to use a modern express methods of diagnostics for the causative agents of tuberculosis and to study their sensitivity to antimycobacterial drugs, especially by using molecular genetics methods.

Socio-demographic Profile of MDR-TB and XDR-TB Patients Admitted in DR-TB Centre, North India

BACKGROUND

As per WHO Global TB report (2018), 10.0 million people developed TB in 2017. India accounted for 20 % of world cases. Globally, 3.5 % of new cases and 18% of previously treated cases had MDR-TB. Corresponding figures for India are 2.8 % and 12 %. Among cases of MDR-TB in 2017, 8.5% were estimated to have XDR-TB. Drug resistant TB cases are on rise and needs planning and research for its treatment and control.

MATERIALS AND METHODS

A retrospective study was conducted on MDR-TB and XDR-TB patients to evaluate social and demographic profile of these patients in Bihar.

RESULTS

A total of 700 (530 males and 170 females) MDR-TB and 51 (40 males and 11 females) XDR-TB patients were analyzed, which revealed 293 (41.86 %) patients of MDR-TB and 23 (45.10 %) patients of XDR-TB in the age group of 15 to 25 years. Mean age of MDR-TB patients in this age group was 20.52 years and for XDR-TB 21.17 years.

CONCLUSION

Drug Resistant Tuberculosis Control Programme should focus adequately on youth in state of Bihar, India.