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Rifampicin, essential for long-term tuberculosis treatment, requires rigorous control of non-therapeutic impurities due to their potential adverse, including mutagenic effects. Reports on control strategies for genotoxic impurities in rifampicin have been limited. This study introduced an analytical method to identify potential genotoxic impurities from the synthesis of raw materials. The structure of the 25-deacetyl-23-acetyl-rifampicin genotoxic impurity was confirmed using nuclear magnetic resonance, high-resolution mass spectrometry (HRMS), and high-performance liquid chromatography (HPLC). An HPLC-HRMS method was established and validated for detecting another genotoxic impurity, 1-amino-4-methylpiperazine, adhering to the International Council on Harmonization guidelines, which include specificity, linearity, detection and quantification limits, accuracy, precision, and robustness. These developments improve the quality control strategy for genotoxic impurities in rifampicin, ensuring product safety., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Rifampicin (RFP) has demonstrated potent antibacterial effects in the treatment of pulmonary tuberculosis. However, the serious adverse effects on the liver intensively limit the clinical usage of the drug. Deacetylation greatly reduces the toxicity of RFP but also retains its curative activity. Here, we found that Krüppel-like factor 15 (KLF15) repressed the expression of the major RFP detoxification enzyme Cyp3a11 in mice via both direct and indirect mechanisms. Knockout of hepatocyte KLF15 induced the expression of Cyp3a11 and robustly attenuated the hepatotoxicity of RFP in mice. In contrast, overexpression of hepatic KLF15 exacerbated RFP-induced liver injury as well as mortality. More importantly, the suppression of hepatic KLF15 expression strikingly restored liver functions in mice even after being pretreated with overdosed RFP. Therefore, this study identified the KLF15-Cyp3a11 axis as a novel regulatory pathway that may play an essential role in the detoxification of RFP and associated liver injury. SIGNIFICANCE STATEMENT: Rifampicin has demonstrated antibacterial effects in the treatment of pulmonary tuberculosis. However, the serious adverse effects on the liver limit the clinical usage of the drug. Permanent depletion and transient inhibition of hepatic KLF15 expression significantly induced the expression of Cyp3a11 and robustly attenuated mouse hepatotoxicity induced by RFP. Overall, our studies show the KLF15-Cyp3a11 axis was identified as a novel regulatory pathway that may play an essential role in the detoxification of RFP and associated liver injury., (Copyright © 2024 by The Author(s).)

During our screening for antibiotics against Mycobacterium avium complex (MAC) with a mass spectrometry network-based indexing approach, a new compound named kimidinomycin was isolated from the culture broth of Streptomyces sp. KKTA-0263 by solvent extraction, HP20 column chromatography, and preparative HPLC. From the structural elucidation, the compound possesses a 38-membered macrolide structure with an N-methylguanidyl group at the terminal side chain. The compound exhibited antimycobacterial activity against M. avium, M. intracellulare, M. smegmatis, and M. bovis BCG with respective MIC values of 12.5, 0.78, 12.5, and 25.0 µg ml -1 ., (© 2021. The Author(s), under exclusive licence to the Japan Antibiotics Research Association.)

Objectives: Anti-TB drugs-isoniazid and rifampicin induced hepatotoxicity present a significant clinical problem. We aimed to evaluate the beneficial effect of gallic acid in anti-TB drug-induced liver injury in vivo and for the mechanism of action, we explored the influence of gallic acid on Nrf2 and NF-κB pathways., Methods: We assessed serum liver function tests and histopathological analysis for the preventive effect of gallic acid on liver injury. For exploring the beneficial mechanism, we studied Nrf2 and NF-κB signalling pathways using molecular assays. Subsequently, we conducted in vitro cytotoxicity assays with Nrf2(ML385) and NF-κB(BAY 11-7085) antagonists., Key Findings: Gallic acid co-administration attenuated the elevation of liver function enzymes, hepatic necrosis and inflammation compared to the anti-TB drug treatment alone. Mechanistic investigations reveal that gallic acid increased Nrf2 activation and induction of its downstream targets, preventing cytotoxicity by isoniazid and rifampicin. The protective effect of gallic acid diminished in the presence of Nrf2 antagonists in vitro. Furthermore, we found that gallic acid treatment inhibited NF-κB/TLR-4 axis upregulated by the anti-TB drugs., Conclusions: Gallic acid is effective in preventing isoniazid and rifampicin induced hepatotoxicity in vivo by improving the redox homeostasis by activating Nrf2 and inhibiting NF-κB signalling pathways., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Prolonged treatment with rifampicin (RFP), a first-line antibacterial agent used in the treatment of drug-sensitive tuberculosis, may cause various side effects, including metabolic disorders. The nuclear factor (erythroid-derived 2)-like 2 (NFE2L2, also known as NRF2) plays an essential regulatory role in cellular adaptive responses to stresses via the antioxidant response element (ARE). Our previous studies discovered that NRF2 regulates the expression of CCAAT-enhancer-binding protein β (Cebpb) and peroxisome proliferator-activated receptor gamma (Pparg) in the process of adipogenesis. Here, we found that prolonged RFP treatment in adult male mice fed a high-fat diet developed insulin resistance, but reduced fat accumulation and decreased expression of multiple adipogenic genes in white adipose tissues. In 3 T3-L1 preadipocytes, RFP reduced the induction of Cebpb, Pparg and Cebpa at mRNA and protein levels in the early and/or later stage of hormonal cocktail-induced adipogenesis. Mechanistic investigations demonstrated that RFP inhibits NRF2-ARE luciferase reporter activity and expression of NRF2 downstream genes under normal culture condition and in the early stage of adipogenesis in 3 T3-L1 preadipocytes, suggesting that RFP can disturb adipogenic differentiation via NRF2-ARE interference. Taken together, we demonstrate a potential mechanism that RFP impairs adipose function by which RFP likely inhibits NRF2-ARE pathway and thereby interrupts its downstream adipogenic transcription network., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Tuberculosis (TB) is one of the deadliest infectious diseases in humankind history. Although, drug sensible TB is slowly decreasing, at present the rise of TB cases produced by multidrug-resistant (MDR) and extensively drug-resistant strains is a big challenge. Thus, looking for new therapeutic options against these MDR strains is mandatory. In the present work, we studied, in BALB/c mice infected with MDR strain, the therapeutic effect of supra-pharmacological doses of the conventional primary antibiotics rifampicin and isoniazid (administrated by gavage or intratracheal routes), in combination with recombinant human hepatocyte growth factor (HGF). This high dose of antibiotics administered for 3 months, overcome the resistant threshold of the MDR strain producing a significant reduction of pulmonary bacillary loads but induced liver damage, which was totally prevented by the administration of HGF. To address the long-term efficiency of this combined treatment, groups of animals after 1 month of treatment termination were immunosuppressed by glucocorticoid administration and, after 1 month, mice were euthanized, and the bacillary load was determined in lungs. In comparison with animals treated only with a high dose of antibiotics, animals that received the combined treatment showed significantly lower bacterial burdens. Thus, treatment of MDR-TB with very high doses of primary antibiotics particularly administrated by aerial route can produce a very good therapeutic effect, and its hepatic toxicity can be prevented by the administration of HGF, becoming in a new treatment modality for MDR-TB., (© 2019 Wiley Periodicals, Inc.)

First-line antituberculosis drugs, namely, isoniazid (INH), rifampicin (RIF), and pyrazinamide (PZA), contribute to diverse pathological complications. Testicular toxicity is one such complication. Berberis aristata DC is an herb with potentially curative characteristics. The aim of this study was to test whether extract of Berberis aristata DC (Berberidaceae) has curing potential against testicular toxicity. Characterization of extract was done using ultra-performance liquid chromatography along with acute toxicity testing. Antioxidant activity of extract was checked by DPPH inhibition assay and H 2 O 2 scavenging assay. Rats were dosed once daily for 28 days in groups: control group (saline), toxicant group (30.85 mg/kg body weight INH + 61.7 mg/kg body weight RIF + 132.65 mg/kg body weight PZA), treatment groups (TB drugs + 150/300 mg/kg body weight extract) and standard group (TB drugs +100 mg/kg body weight silymarin). Spectrophotometric evaluations of lipid peroxidation (LPO), reduced glutathione (GSH), superoxide dismutase (SOD), glutathione-S-transferase (GST), and catalase (CAT) content in testes were done using standard protocols. DNA fragmentation and histopathological studies were performed to check the damage at the cellular level. Acute toxicity studies revealed LD 50 > 5 g/Kg body weight of B. aristata extract. IC 50 for DPPH free-radical scavenging activity and H 2 O 2 scavenging assay were 44.78 µg/mL and 85.28 µg/mL, respectively. Results revealed significant increase in thiobarbituric acid reactive substances, decrease in glutathione and different antioxidants levels, DNA fragmentation pattern, and changes in histology in toxicant group. All the changes were absent in high-dose (300 mg/kg body weight) extract treatment group. This work proved that B. aristata extract has protective efficacy against testicular damage caused by anti-TB drugs.

Methimazole (MMI) is a widely used drug for hyperthyroidism. However, its clinical use is associated with hepatotoxicity. Though the precise mechanism of hepatic damage is still far from clear, role of metabolic activation and reactive metabolites have been implicated. The present study was designed to investigate the role of enzyme induction in bioactivation based hepatotoxicity of methimazole in mice. Thirty male mice were randomly divided into five groups. Hepatotoxicity was induced by single intraperitoneal injection of methimazole (1000mg/kg). Pretreatment with rifampicin which is a potent enzyme inducer was carried out for 6 days prior to administration of methimazole. The extent of hepatic damage was determined by measuring serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) along with histopathological grading of liver samples. The elevated levels of biochemical markers by methimazole were potentiated by pretreatment with rifampicin. This potentiation of hepatic injury was also observed in liver histopathological examination. These findings suggest induction of microsomal enzymes as a potentiating factor of methimazole induced hepatotoxicity.

Objective: Pulmonary delivery of antibiotics will decrease the required dose for efficient treatment of lung infections and reduce systemic side effects of the drug. The objective was to evaluate the applicability of poly(ethylene carbonate) (PEC) for the preparation of inhalable, antibiotic-containing particles., Methods: Rifampicin (RF)-loaded microparticles were prepared by electrospraying a carrier matrix of polylactic acid (PLA) with 0%, 5% and 10% PEC., Key Findings: Prepared particles had an aerodynamic diameter between 4 and 5 μm. Within 60 min, PEC-containing particles released 35-45% of RF, whereas PLA particles released only 15% of RF. Irrespective of particle composition, uptake of RF by macrophages was improved to 40-60% when formulated in microparticles compared to 0.4% for RF in solution, and intracellular localisation of particles was confirmed using confocal microscopy. Effect on macrophage and alveolar cell viability was similar for all particles whereas the minimal inhibitory concentrations against Pseudomonas aeruginosa and Escherichia coli for RF-containing PEC particles were twofold lower than for PLA particles, explained by the faster release of RF from PEC-containing particles., Conclusions: The inclusion of PEC in PLA microparticles increased the release of RF and the inhibitory effect against two bacteria species while displaying physical particle properties similar to PLA particles., (© 2018 Royal Pharmaceutical Society.)

Objectives: The aim of this study is to evaluate the hepatoprotective effect of Lasianthera africana (Icacinaceae) against isoniazid (INH) and rifampicin (RIF)-induced liver damage in rats., Methods: The hepatoprotective effects of hot aqueous L. africana (HALA) leaf extract (0.1-1 g/kg) and silymarin (50 mg/kg) were assessed in a model of oxidative liver damage induced by RIF and INH (100 mg/kg each) in Wistar rats for 28 days. Biochemical markers of hepatic damage such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were assessed. The antioxidant statuses of plasma glutathione peroxidase (GSPx), glutathione reductase (GSH), catalase (CAT) and superoxide dismutase (SOD) and lipid peroxidation were evaluated., Results: The pretreatment of INH and RIF decreased hematological indices and the antioxidant levels (P < 0.001) and increased the levels of liver marker enzymes (P < 0.001). However, pretreatment with HALA extract and silymarin provoked significant elevation of hematological indices. The levels of AST, ALT, and ALP were depressed (P < 0.001). Total triglycerides, total cholesterol, total bilirubin and low-density lipoprotein were decreased (P < 0.001). However, high-density lipoprotein, bicarbonate, and electrolytes like chloride and potassium were elevated (P < 0.001), but sodium was depressed (P < 0.05). Additionally, GSH, GSPx, SOD and CAT were elevated (P < 0.01) and malondialdehyde was depressed (P < 0.001) when compared to the RIF-INH-treated rats. Histopathological evaluations support hepatoprotective activity., Conclusion: This study demonstrated that HALA leaf extract attenuated RIF-INH-induced hepatotoxicity. L. africana could be exploited in management of RIF-INH-induced hepatitis., (Copyright © 2018 Shanghai Changhai Hospital. Published by Elsevier B.V. All rights reserved.)

Background: The delivery of antitubercular drugs through direct lung targeting can lead to reduction in the dose as well as side effects of the drug. In the present investigation, carrier (lactose)-based dry-powder inhaler of rifampicin was prepared to achieve direct targeting of the drug into the lungs., Methods: The dry powder inhaler formulation was prepared by simply mixing micronized rifampicin with coarse and fine lactose preblend. Preliminary blends of the drug were prepared with various lactose grades (Inhalac ® , Respitose, ® and Lactohale ® ). Rotahaler ® and Revolizer ® were evaluated for the performance. The 3 2 factorial design was used to optimize the amount of drug (X 1 ) and amount of fine lactose (X 2 ). In vitro lung deposition was carried out using Andersen Cascade Impactor. The % cell viability studies of the formulation were carried out using murine macrophage J774 cell lines. The in vivo toxicity was determined using histopathology. Further in vivo pulmonary pharmacokinetics of the developed dry-powder inhaler (DPI) formulation was carried out in comparison to the marketed formulation in the rat lungs., Results: Based on preliminary trials, Inhalac 230 and Inhalac 400 were selected as coarse and fine lactose grades, respectively. Rotahaler ® exhibited better DPI performance with the evaluated drug blends. The mass median aerodynamic diameter (MMAD) was in the range of 4.3-5.8 μm with the maximum fine particle fraction of 28.9%. The formulation exhibited negligible cytotoxicity on macrophage J774 cell lines with about 75%-80% cell viability at 6- and 12-hour exposure. The histopathological examination revealed negligible toxicity of DPI in comparison to the marketed formulation. The in vivo pulmonary pharmacokinetic studies of the DPI formulation in rats showed higher drug concentration in lungs in comparison to the marketed formulation., Conclusion: The carrier-mediated dry-powder inhaler of rifampicin could serve as an improved and efficient system for local targeting of drugs into the lungs.

Endoplasmic reticulum (ER) stress-induced cell injury plays an important role in the development of drug-induced liver injury (DILI). However, little is known about the contribution of ER stress to RFP-induced cell injury. In our study, L02 cells were treated with different concentrations of RFP for different time intervals, and cell apoptosis, the survival rate, and the gene and protein expression of GRP78, PERK, ATF4, and CHOP were measured. Additionally, L02 cells were transfected with CHOP-siRNA or a CHOP-over expression plasmid or administered 4-PBA before treatment with RFP. We found that RFP increased the cell apoptosis rate, decreased cell survival, and increased the protein and gene levels of GRP78, PERK, ATF4 and CHOP in both a dose-dependent and a time-dependent manner. Following the transient knockdown of CHOP and treatment with RFP, cell apoptosis decreased and the survival rate increased. Overexpression of CHOP produced the opposite effects. Treatment with 4-PBA decreased the protein and gene expression of GRP78, PERK, ATF4 and CHOP. Additionally, 4-PBA reduced cell apoptosis, increased cell survival and decreased the level of ALT, AST, AKP, LDH and ATP in the cell culture supernatant. These results indicate that 4-PBA alleviates RFP-induced injury in L02 cells via inhibition of the PERK-ATF4-CHOP pathway., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This work aimed to design, develop, and characterize a lipid nanocarrier system for the selective delivery of rifabutin (RFB) to alveolar macrophages. Lipid nanoparticles, specifically nanostructured lipid carriers (NLC), were synthetized by the high-shear homogenization and ultrasonication techniques. These nanoparticles were designed to exhibit both passive and active targeting strategies to be efficiently internalized by the alveolar macrophages, traffic to the acidified phagosomes and phagolysosomes, and release bactericidal concentrations of the antituberculosis drug intracellularly. NLC that could entrap RFB were prepared, characterized, and further functionalized with mannose. Particles' diameter, zeta potential, morphology, drug% entrapping efficiency, and drug release kinetics were evaluated. The mannose coating process was confirmed by Fourier transform infrared. Further, the cytotoxicity of the formulations was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay in A549, Calu-3, and Raw 264.7 cells. The diameter of NLC formulations was found to be in the range of 175-213 nm, and drug entrapping efficiency was found to be above 80%. In addition, high storage stability for the formulations was expected since they maintained the initial characteristics for 6 months. Moreover, the drug release was pH-sensitive, with a faster drug release at acidic pH than at neutral pH. These results pose a strong argument that the developed nanocarrier can be explored as a promising carrier for safer and more efficient management of tuberculosis by exploiting the pulmonary route of administration.

Background: The lung is the primary entry site and target for Mycobacterium tuberculosis; more than 80% of the cases reported worldwide are of pulmonary tuberculosis. Hence, direct delivery of anti-tubercular drugs to the lung would be beneficial in reducing both, the dose required, as well as the duration of therapy for pulmonary tuberculosis. In the present study, microsphere-based dry powder inhalation systems of the anti-tubercular drugs, rifampicin and rifabutin, were developed and evaluated, with a view to achieve localized and targeted delivery of these drugs to the lung., Methods: The drug-loaded chitosan microparticles were prepared by an ionic gelation method, followed by spray-drying to obtain respirable particles. The microparticles were evaluated for particle size and drug release. The drug-loaded microparticles were then adsorbed onto an inhalable lactose carrier and characterized for in vitro lung deposition on an Andersen Cascade Impactor (ACI) followed by in vitro uptake study in U937 human macrophage cell lines. In vivo toxicity of the developed formulations was evaluated using Sprague Dawley rats., Results: Both rifampicin and rifabutin-loaded microparticles had MMAD close to 5 μm and FPF values of 21.46% and 29.97%, respectively. In vitro release study in simulated lung fluid pH 7.4 showed sustained release for 12 hours for rifampicin microparticles and up to 96 hours for rifabutin microparticles, the release being dependent on both swelling of the polymer and solubility of the drugs in the dissolution medium. In vitro uptake studies in U937 human macrophage cell line suggested that microparticles were internalized within the macrophages. In vivo acute toxicity study of the microparticles in Sprague Dawley rats revealed no significant evidence for local adverse effects., Conclusion: Thus, spray-dried microparticles of the anti-tubercular drugs, rifampicin and rifabutin, could prove to be an improved, targeted, and efficient system for treatment of tuberculosis.

Rifampicin (RIF) was encapsulated into solid lipid nanoparticles (SLNs) to overcome its poor and unreliable oral bioavailability. Novel microemulsification method with high drug loading (50%) and entrapment efficiency (∼67%) was developed (Indian Patent Application 3356/DEL/2013). RIF-SLNs were characterized using TEM, AFM, DSC and XRD. Near neutral SLNs (zeta -3.5 ± 0.8), with average particle size of 130.0 ± 22.6 nm showed 70.12% release in phosphate buffer pH 6.8 in 9 days. Single oral dose (50mg/kg) pharmacokinetic studies in Wistar rats indicated 8.14 times higher (in comparison to free RIF) plasma bioavailability with sustained levels for 5 days. Pharmacodynamic parameters viz. TMIC (120 h; time for which plasma levels were above MIC of 0.2 μg/ml), AUC0-∞/MIC (1868.9h) and Cmax/MIC (75.6) for RIF-SLNs were greater than free RIF by 2.5, 8.2 and 6.6 times, respectively. Similar LD50 (1570 mg/kg) and absence (or reversal in satellite group) of adverse events in repeat dose (three doses; highest dose was up to 50 times the human therapeutic dose) toxicity studies confirmed safety of RIF-SLNs. Improved pharmacokinetic profile of RIF-SLNs can be translated to a reduced dose and dosage frequency of RIF, thus resulting in lower or no hepatotoxicity commonly associated with its use., (Copyright © 2015 Elsevier B.V. All rights reserved.)

1,5-Diphenyl pyrroles were previously identified as a class of compounds endowed with high in vitro efficacy against M. tuberculosis. To improve the physical chemical properties and drug-like parameters of this class of compounds, a medicinal chemistry effort was undertaken. By selecting the optimal substitution patterns for the phenyl rings at N1 and C5 and by replacing the thiomorpholine moiety with a morpholine one, a new series of compounds was produced. The replacement of the sulfur with oxygen gave compounds with lower lipophilicity and improved in vitro microsomal stability. Moreover, since the parent compound of this family has been shown to target MmpL3, mycobacterial mutants resistant to two compounds have been isolated and characterized by sequencing the mmpL3 gene; all the mutants showed point mutations in this gene. The best compound identified to date was progressed to dose-response studies in an acute murine TB infection model. The resulting ED(99) of 49 mg/Kg is within the range of commonly employed tuberculosis drugs, demonstrating the potential of this chemical series. The in vitro and in vivo target validation evidence presented here adds further weight to MmpL3 as a druggable target of interest for anti-tubercular drug discovery.

Numerous studies support the fact that a genetically diverse mouse population may be useful as an animal model to understand and predict toxicity in humans. We hypothesized that cultures of hepatocytes obtained from a large panel of inbred mouse strains can produce data indicative of inter-individual differences in in vivo responses to hepato-toxicants. In order to test this hypothesis and establish whether in vitro studies using cultured hepatocytes from genetically distinct mouse strains are feasible, we aimed to determine whether viable cells may be isolated from different mouse inbred strains, evaluate the reproducibility of cell yield, viability and functionality over subsequent isolations, and assess the utility of the model for toxicity screening. Hepatocytes were isolated from 15 strains of mice (A/J, B6C3F1, BALB/cJ, C3H/HeJ, C57BL/6J, CAST/EiJ, DBA/2J, FVB/NJ, BALB/cByJ, AKR/J, MRL/MpJ, NOD/LtJ, NZW/LacJ, PWD/PhJ and WSB/EiJ males) and cultured for up to 7 days in traditional 2-dimensional culture. Cells from B6C3F1, C57BL/6J, and NOD/LtJ strains were treated with acetaminophen, WY-14,643 or rifampin and concentration-response effects on viability and function were established. Our data suggest that high yield and viability can be achieved across a panel of strains. Cell function and expression of key liver-specific genes of hepatocytes isolated from different strains and cultured under standardized conditions are comparable. Strain-specific responses to toxicant exposure have been observed in cultured hepatocytes and these experiments open new opportunities for further developments of in vitro models of hepatotoxicity in a genetically diverse population., (Copyright © 2010 Elsevier Inc. All rights reserved.)

A new rifamycin derivative 3-(4-cinnamyl-piperazinyl iminomethyl) rifamycin SV (T9) and its sodium salt (T11, Rifacinna((R))) were in vitro, in vivo, toxicologically and clinically investigated in comparison with rifampicin, rifapentine, rifabutin, rifalazil. Our experiments showed that Rifacinna exhibits excellent in vitro activity against Gram(+), Gram (-) aerobic, anaerobic pathogens and mycobacteria. Rifacinna is active against Staphylococcus, Streptococcus spp. including MRSA, with MIC90- 0.06-0.5 mg/L; against Gram(+), Gram (-) anaerobes with MIC90 0.5 - 1 mg/L; against Mycobacterium tuberculosis (MTB) with MIC90 0.062 mg/L; against MDR resistant MTB (25%-30 %) and Mycobacterium avium complex (MAC) strains with MICs 0.6-1.0 mg/L. It shows high intraphagocytic activity against MAC strains (0.06 0.125mg/L). Single daily dose 10 mg/kg provides complete erradication of mycobacteria in experimental generalized tuberculosis. Pharmacological studies established: excellent pharmacokinetic profile following single oral dose 10mg/kg Tmax 5-6 h, C(max) 5-9 mg/L, T1/2 33-34 h; low toxicity; no teratogenic and embryotoxic effects. The clinical study of Rifacinna shows higher therapeutic efficacy than Rifampicin in patients with infiltrative, disseminated and cavitary form of pulmonary tuberculosis, good tolerability and safety profile. Some of the recent patents related to the treatment of tuberculosis are discussed in this review article.

The World Health Organization (WHO) has shown concern about the burden of tuberculosis in the developing countries. Even though rifampicin is an effective drug in the management of tuberculosis, it has been documented to have some toxic effects in humans. Therefore, this study intends to investigate the modulatory effect of vitamins C and E on the hepatotoxicity, sperm quality and brain toxicity of Rifampicin. Forty Wistar albino rats were used, 10 animals per group. Group 1 animals received 0.3 mL of distilled water, the Group 2 animals received the therapeutic dose of rifampicin, Group 3 animals received therapeutic doses of rifampicin plus vitamin E, while Group 4 received therapeutic doses of rifampicin and vitamin C. The administration was performed orally during three months; the animals were sacrificed by cervical dislocation at the end of that period. Blood samples were collected and liver function and lipid profile was analyzed using fully automated clinical chemistry device. The liver, brain and reproductive organs underwent histopathological examination. Sperm samples were collected from the epididymis to achieve count and motility and morphological analysis. Results showed rifampicin alone to raise (p < 0.05) liver function enzymes (Aspartate amino transferase [AST], Serum alanine amino transferase [ALT] and Total Bilirubin) when compared with controls. While the vitamin E treated group showed remarkable protection, the vitamin C treated group showed questionable protection against the rifampicin induced liver damage. Sperm count results showed an important (p < 0.05) increase in the sperm quality in vitamin E and C treated groups. However, the vitamin E plus Rifampicin treated group showed increased lipid peroxidation. The histopathological findings revealed structural damages by rifampicin in liver, brain and epididymis while some remarkable architectural integrity was observed in the antioxidant-treated groups. It can be concluded that vitamin E or C improved sperm quality and protected against the brain damage caused by rifampicin. Moreover, vitamin E demonstrated remarkable hepatoprotection against rifampicin induced damage while vitamin C shows a questionable hepatoprotection.

The objective of the present study was to evaluate the prospective of engineered nanoparticles for selective delivery of an antituberculosis drug, rifabutin, to alveolar tissues. Drug-loaded solid lipid nanoparticles (SLNs) were synthesized and efficiently mannosylated. The formation of uncoated and coated SLNs was characterized by FTIR spectroscopy and SEM studies. A variety of physicochemical parameters such as drug loading, particle size, polydispersity index, zeta potential, and in vitro drug release were determined. The toxicity and targeting potential of the prepared formulation were assessed with alveolar macrophage uptake, hematological studies, and in vivo studies of uncoated and coated SLNs. Ex vivo cellular uptake studies of SLNs formulations in alveolar macrophages depicted almost six times enhanced uptake due to mannose coating. The hematological studies proved mannose-conjugated system to be less immunogenic and suitable for sustained delivery as evaluated against uncoated formulation. Further, the serum level and organ distribution studies demonstrated efficiency of the system for prolonged circulation and spatial delivery of rifabutin to alveolar tissues. Finally, it was concluded that mannose-conjugated SLNs can be exploited for effective and targeted delivery of rifabutin compared to its uncoated formulation and ultimately increasing the therapeutic margin of safety while reducing the side effects.

Rifampicin-encapsulated liposome suspensions were prepared by a chloroform-film method and converted to dry powders by freeze-drying with mannitol as a cryoprotectant. The liposome suspension had multilamellar nanovesicles with 50% rifampicin encapsulation. The liposome dry powder comprised particles with a mass median aerodynamic diameter of 3.4 mum, with 60% present as a fine particle fraction. Rifampicin-encapsulated liposomes were evidently nontoxic to respiratory associated cells, including bronchial epithelial cells, small airway epithelial and alveolar macrophages (AMs). Furthermore, the liposomes did not activate AMs to produce interleukin-1 beta, tumor necrosis factor-alpha, and nitric oxide at a level that would cascade to other inflammatory effects. The minimum inhibitory concentrations against Mycobacterium bovis was 0.2 and 0.8 microM for liposomes containing rifampicin and free rifampicin, respectively. The less negatively charged reconstituted liposome displayed the greatest activity against intracellular growth of M. bovis.

Objective: To study the effect of rifampin (RFP) on the metabonomic profile of rat urine and its relationship with traditional toxicity evaluation of blood biochemical indicators and histopathology., Methods: Thirty-six male Wistar rats were randomly divided into control group, 50 mg/kg RFP group, and 100 mg/kg RFP group, with 12 rats in each group. Rats in each group were given intragastric infusion with a daily dose of 0, 50 mg/kg RFP, and 100 mg/kg RFP for 3, 7, and 14 days, respectively. Then 4 rats in each group were killed on the next day of administration to collect blood samples and liver sample for the determination of blood biochemical indicators and for the pathological analysis of the liver. The urine specimens over 24 hours of each rat were collected before and after each treatment until the rat was killed. 1H nuclear magnetic resonance (1H NMR) spectra of these urine specimens were acquired and subjected to data preprocess and principal component analyses (PCA)., Results: The level of serum total bilirubin of the rat administrated with 100 mg/(kg x d) RFP for 7 days was significantly higher than that of control group (P < 0.05). Mild hepatotoxicity to the rat, treated with RFP of higher dosage (100 mg/kg) and longer duration (14 days), was revealed by the traditional histopathological method. The metabonomic spectra of rat urine in different groups differed from each other; a trajectory bias in determination of rat urine by 1H NMR occurred depending on the administration duration. As demonstrated by 1H NMR spectra of urine in rats treated with RFP, the concentration of urinary citrate and 2-oxoglutarate decreased, along with the remarkable increase of the concentrations of urinary taurine and glucose (compared with those of the control group)., Conclusions: Being consistent with the results of traditional toxicity evaluation measurements, metabonomic method is more sensitive. The 1H-NMR metabonomic profile of the rat urine is closely related with the duration of RFP. The hepatic toxicity induced by RFP is related to the reduction of energy metabolism in tricarboxylic acid cycle and the perturbation of glucose and lipid metabolism.

The present study was aimed at developing and exploring the use of mannosylated dendritic architecture for the selective delivery of an anti-tuberculosis drug, rifampicin (RIF) to alveolar macrophages (AM). The mannosylated dendritic architecture was synthesized and characterized by using IR and NMR spectroscopy. RIF was efficiently loaded into mannosylated dendrimer using dissolution method. Various physicochemical and physiological parameters such as UV, SEM, DSC, drug loading, solubilization, pH dependent in-vitro release, hemolytic toxicity, phagocytic AM uptake and cytotoxicity concerning the mannosylated dendrimer were evaluated. RIF loaded mannosylated dendrimer reduced release rate of drug in pH 7.4, hemolytic toxicity and cytotoxicity; whereas enhanced drug release in pH 5.0 and AM uptake was observed. The present novel dendritic system displayed suitability in terms of biocompatibility and site-specific delivery of antitubercular drug RIF.

Terminalia chebula Gertn. (Combetraceae) is an important herbal drug in Ayurvedic pharmacopea. In the present study, a 95% ethanolic extract of T. chebula (fruit) (TC extract), which was chemically characterized on the basis of chebuloside II as a marker, was investigated for hepatoprotective activity against anti-tuberculosis (anti-TB) drug-induced toxicity. TC extract was found to prevent the hepatotoxicity caused by the administration of rifampicin (RIF), isoniazid (INH) and pyrazinamide (PZA) (in combination) in a sub-chronic mode (12 weeks). The hepatoprotective effect of TC extract could be attributed to its prominent anti-oxidative and membrane stabilizing activities. The changes in biochemical observations were supported by histological profile.

Aim: To study the role of N-acetylcysteine (NAC) as a protective agent in rifampicin (RMP)-induced oxidative hepatic injury of young rats., Methods: Hepatic injury was produced by giving 50 mg/kg body weight/day of RMP for 3 wk. A dose of NAC (100 mg/kg body weight/day) was given in combination with RMP intraperitoneally. Analysis of lipid peroxidation, thiol levels, cytochrome P450, superoxide dismutase (SOD), catalase, glutathione peroxidase, reductase and transferase were estimated in liver along with the body weight, liver weight and histological observations., Results: RMP exposure resulted in no change in body and liver weight while antioxidative enzymes were altered but the non protein thiol (GSH) status was well preserved. Cytochrome P450 system and peroxidation of lipids were induced by RMP exposure. Partial protection was observed with NAC against RMP-induced changes in liver, which was evidenced from the prevention of increase in lipid peroxidation and the reduction in SOD and catalase enzyme levels., Conclusion: NAC protects young rats against RMP-induced oxidative hepatic injury.

Although combined treatment of isoniazid (INH) and rifampicin (RIF) has been documented to induce hepatotoxicity and hepatocellular damage, their effect on liver tissue phospholipids is still unknown. Because phospholipids constitute an integral part of hepatocellular membrane, studies were conducted to evaluate the effect of individual and combined treatment of INH and RIF on liver tissue phospholipids in rabbits. Simultaneous administration (i.p.) of INH and RIF (group IV; n = 6), each at a dose of 25 mg/kg for 11 days, caused a significant elevation of phospholipids in plasma from day 5 till day 11. This treatment also caused a significant fall in total inorganic phosphorous, phosphatidylcholine (PC), and cardiolipin (CL) with concomitant increase in phosphatidylethanolamine (PE) and phosphatitylserine (PS) subfractions of phospholipids in the liver tissue of rabbits. Though INH-alone treatment (group II; n = 5) produced a significant fall in total inorganic phosphorous content in the liver tissue, the phospholipid subfractions remain unaltered. RIF-alone treatment (group III; n = 5) did not produce any alteration in phospholipids and their subfractions in liver tissue and plasma of rabbits, and they were comparable to saline-treated control (group I; n = 5). It is likely that simultaneous treatment of INH and RIF could cause choline deficiency, resulting in lowering of phospholipids in the hepatocellular membrane and obstruction of lipoprotein synthesis, culminating in liver injury.

Co-administration of isoniazid (INH) and rifampicin (RIF) encapsulated in lung specific stealth liposomes at one third of their recommended doses of 12 and 10 mg/kg b.wt., respectively, exhibited a sustained release of these drugs in plasma (5 days) and lungs, liver and spleen (7 days). At these concentrations, T(max) and area under curve (AUC) values of liposomal drugs were more than that observed with free drugs. The elimination constant (Kel) was higher for liposomal INH (-0.034+/-0.008) and RIF (-0.017+/-0.009) compared with free INH (-0.392) and RIF (-0.243). Chemotherapeutic efficacy of once weekly-administered liposomal drugs for 6 weeks reduced the mycobacterial load significantly in lungs, liver and spleen of infected mice compared with untreated animals.

-The genotoxic effect of rifampicin (RMP), one of the most active antituberculosis agents is studied. Also, the possible protection provided by the natural antioxidant vitamins C (VC) and E (VE) against the genotoxic effect of RMP is assessed. Mice were orally treated by gavage with 10, 50, 150 and 300 mg RMP kg(-1) body weight (bw). Also, oral treatment was conducted with RMP plus the vitamins. Mice received 300 mg RMP kg(-1) bw plus 100, 200 and 400mg VC or VE kg(-1) bw. Samples were taken 24h after the treatment. Repeated treatments with: (1) the therapeutic dose of RMP (10 mg kg(-1) bw); (2) RMP plus a dose of 25, 50 and 75 mg VC kg(-1); (3) RMP plus 10, 20 and 40 mg VE kg(-1) bw for 30 consecutive days were conducted. The tested doses of RMP induced a significant increase in the percentage of chromosome aberrations. However, a lower percentage of chromosome aberrations was observed when animals were treated with the therapeutic dose for 30 consecutive days. The obtained results revealed that chromosome aberrations induced by RMP decreased to a significant extent when mice were treated with RMP plus VC. The repeated doses of VC reduced the percentage of chromosome aberrations induced by RMP in a significant and dose-dependent manner. On the other hand, repeated doses of VE were not very effective in reducing the percentage of chromosome aberrations induced by RMP. Only the highest dose (3 x 40 mg kg(-1) bw) showed a significant effect (P<0.01). The results on the induction of chromosome damage clearly show that only VC appears able to efficiently protect the bone-marrow cells when given together with RMP, while no significant reduction in the yield of chromosome aberrations was observed for VE in combination with the antituberculosis drug.

We examined the effects of rifampicin on osteoblast-like cells derived from adult human bone in vitro. Cancellous bone was collected from five different individuals during elective orthopaedic operations and cultured in antibiotic-free media. Total DNA, 3H-thymidine incorporation and alkaline phosphatase (ALP) activity were measured after the cells were cultured for 4 days in media containing concentrations of rifampicin ranging from 0 to 1000 microg/ml. Mean total DNA was decreased at concentrations of 10 microg/ml and above in the cultures obtained from four out of five individuals but these decreases were significant in the cultures from only two individuals. 3H-thymidine incorporation, a more sensitive indicator of change in cell proliferation, and ALP activity were significantly decreased (P < 0.05) in all of the cultures containing 3 and 7 microg/ml, respectively. In the clinical setting, serum concentrations of rifampicin often exceed 10 microg/ml after systemic administration. The present study has shown that rifampicin, at these concentrations, can inhibit the proliferation of osteoblast-like cells in vitro. Further studies should be carried out to assess whether rifampicin is detrimental to the bone repair process in vivo.

Strategies to improve patient compliance in tuberculosis chemotherapy include the use of sustained release drug delivery systems. In this study, Poly (DL-lactide-co-glycolide) (PLG) microparticles containing a combination of isoniazid and rifampicin were developed as sustained release carrier systems. A single dose of PLG microparticles exhibited a sustained release of isoniazid and rifampicin in vivo up to 7 and 6 weeks, respectively. Free drugs (in combination) injected in the same doses were detectable in vivo up to 24 h only. One dose of PLG microparticles cleared bacteria more effectively from lungs and liver in an experimental murine model of tuberculosis after low-dose PLG combination drug therapy and in liver after high-dose PLG combination drug therapy as compared with a daily administration of the free drugs. These results suggest that PLG microparticles offer an improvement for tuberculosis chemotherapy over the conventional treatment.

We have previously reported that paclitaxel (Taxol) is a potent inducer of cytochrome P-450 (CYP) 3A protein and CYP3A mRNA in human hepatocyte cultures. Here we report that Taxol increased CYP3A-dependent testosterone 6beta-hydroxylation in intact hepatocytes. This effect was concentration-dependent, with maximal increase in enzyme activity being observed at 10 microM Taxol. Treatment of hepatocyte cultures with concentrations of Taxol higher than 10 microM caused a dose-dependent decrease in testosterone 6beta-hydroxylase activity, amount of CYP3A protein, and total protein synthesis. The maximal CYP3A activity detected after treatment with Taxol or rifampicin was similar in six separate human hepatocyte cultures, suggesting that the cultures have achieved a limit of maximally inducible CYP3A. The fold increase in enzyme activity, however, was different and was inversely related to the level of expression in untreated hepatocytes, with the greatest increases being observed in the hepatocytes that expressed the lowest basal level of CYP3A. Pretreatment of hepatocytes with triacetyloleandomycin resulted in a 90% inhibition of testosterone 6beta-hydroxylase activity. Our results demonstrate the use of human hepatocyte cultures to investigate the induction of cytochrome P-450 by xenobiotics in intact cells and stress the importance of large dose-response studies as well as the need to assess toxicity in these investigations. The response to inducers of CYP3A activity were very consistent among different hepatocyte donors. Absolute values of testosterone 6beta-hydroxylase activity did not vary more than 2- and 5-fold in induced and untreated hepatocytes, respectively.

Combination therapy with anti-HIV drugs and opportunistic infection drugs is a common practice in treatment of AIDS patients. Although toxic effects of most individual therapies are known, the toxic potential of most combination therapies has not been established. To understand the toxic consequences of combination therapies, the commonly used anti-HIV drug 3'-azido-3'-deoxythymidine (AZT) and tuberculosis infection therapies pyrazinamide, isoniazid, and rifampicin were evaluated by 13-week gavage studies in B6C3F1 mice, either alone or AZT in combination with one of the antituberculosis drugs. The doses include AZT 100, 200, and 400; pyrazinamide 1000 and 1500; isoniazid 50, 100, and 150; and rifampicin 100, 200, and 400 mg/kg/day. AZT alone caused hematopoietic toxicity with dose-related bone marrow suppression, macrocytic anemia, and thrombocytosis. Pyrazinamide or isoniazid alone at the doses tested did not cause significant toxicity. Rifampicin alone caused hematopoietic toxicity and possibly mild hepatic toxicity. Pyrazinamide below 10 times the therapeutic dose when given with AZT did not increase the hematological toxicity of AZT. Isoniazid markedly increased the hematological toxicity of AZT and contributed to mortality at 3 to 4 times the therapeutic dose combinations. Administration of rifampicin with AZT at the calculated therapeutic doses resulted in toxicity of far greater magnitude than that caused by AZT or rifampicin alone. Combination treatment with AZT and rifampicin caused severe anemia with mortality at 2 to 4 times the therapeutic dose combinations. However, AZT did not enhance the hepatotoxicity of rifampicin. Increased hematopoietic toxicity of AZT when given in combination with the above antituberculosis drugs may be due to changes in the metabolism of AZT. Results of these studies indicate that toxicological effects of combination therapies could be considerably more severe than and different from the toxicity of individual therapies.

One recent promising development in the modification of drug formulations to improve chemotherapy is the use of a liposome-mediated drug delivery system. The efficacies of isoniazid and rifampin encapsulated in lung-specific stealth liposomes were evaluated by injecting liposomal drugs and free drugs into tuberculous mice twice a week for 6 weeks. Liposome-encapsulated drugs at and below therapeutic concentrations were more effective than free drugs against tuberculosis, as evaluated on the basis of CFUs detected, organomegaly, and histopathology. Furthermore, liposomal drugs had marginal hepatotoxicities as determined from the levels of total bilirubin and hepatic enzymes in serum. The elimination of mycobacteria from the liver and spleen was also higher with liposomal drugs than with free drugs. The encapsulation of antitubercular drugs in lung-specific stealth liposomes seems to be a promising therapeutic approach for the chemotherapy of tuberculosis.

The conventional W/O/W emulsions are readily taken up by the reticuloendothelial system (RES) so that it is necessary to develop either stealth type or tissue specific multiple emulsion for effective targeting. A multiple emulsion system W/O/W containing rifampicin as encapsulant (W/O/W) was prepared. The droplet size was kept small to study targeting independent of passive embolism of larger droplets in the lung capillaries. It was characterised in vitro for drug release through a treated cellophane membrane. A prolonged first order drug release was observed. The W/O/W multiple emulsion system was coated with an o-palmitoyl derivative of mannan (mol.wt. 20,000) to assess its toxicity in vitro and its distribution behaviour in vivo. The multiple emulsion was found to be non toxic at 0.2 ml formulation/10(6) cells level in presence or absence of serum. An intravenous injection of the polysaccharide coated multiple emulsion was given and the tissue distribution of the drug after 1 h and 24 h was investigated. A significant enhancement in lung uptake and a decreased internalisation by spleen was noticed.

The genotoxicity of rifampicin was tested for sister chromatic exchange in bone marrow cells and for structural chromosomal aberrations in mouse germ cells. Sister chromatid exchange frequency increased after 160, 240 and 310 mg kg-1 body wt. doses but not after 80 mg kg-1. In spermatocytes, 80 mg kg-1 rifampicin increased the frequency of chromosomal aberrations from the 3.5% control level to 14% after 1 day and 34.5% after 7 days.

Data of in vitro and in vivo investigations of antimicrobial activity of preparation K carried out both by the authors and by other researchers and pharmacological properties of this preparation have been summarized. Preparation K has been obtained from medicinal plant of the Asteraceae family. It is a natural composition of two antibiotics and of a number of minor compounds. The preparation possesses a wide spectrum of biological action. It is antimicrobially active against gram-positive bacteria, some species of gram-negative bacteria, fungi-dermatophytes including antibiotic-resistant strains. It is not toxic for animals, stimulates some defensive reactions of macroorganism, has immunomodulating, anti-inflammatory, anti-exudative, keratolytic properties. Preparation K is efficient for treatment of experimental mycoses of animals and is clinically tested as a local agent for treatment of dermatomycoses.

The effects of pyridoxine (PN) on rifampicin (RMF) toxicity were investigated by both in vivo and in vitro methods. RMF (30 mg/kg) was injected intraperitoneally and PN(150 mg/kg) was administered orally to rats for 10 consecutive days. After treatment, clinical chemistry and hematologic profiles were measured. RMF and PN plus RMF did not show any adverse effects at this in vivo experimental condition. Thymidine incorporations of mice bone marrow cells were examined in vitro. RMF showed a decrease in thymidine uptake in a dose-dependent manner, but PN showed a reversal of the thymidine uptake suppression caused by RMF (p < 0.01). On the other hand, PN showed a decrease in thymidine uptake at a high concentration level.