Lipid Nanocarrier-Mediated Drug Delivery System to Enhance the Oral Bioavailability of Rifabutin.

Rifabutin (RFB) is prescribed for the treatment of tuberculosis infections as well as Mycobacterium avium complex (MAC) infection in immunocompromised individuals and HIV patients. With a view to develop a sustained release oral solid lipid nanoformulation (SLN), RFB was encapsulated in glyceryl monostearate (GMS) nanoparticles. The rifabutin solid lipid nanoparticles (RFB-SLNs), prepared by the solvent diffusion evaporation method, had a size of 345 ± 17.96 nm and PDI of 0.321 ± 0.09. The stability of RFB-SLNs was investigated in simulated gastric fluid (SGF) pH 2.0, simulated intestinal fluid (SIF) pH 6.8 and physiological buffer (PBS) pH 7.4. The gastric medium did not affect the SLNs and were found to be stable, while a sustained release was observed in SIF up to 48 h and in PBS up to 7 days. The pharmacokinetic profile of a single oral administration of RFB-SLNs in mice showed maintenance of therapeutic drug concentrations in plasma for 4 days and in the tissues (lungs, liver and spleen) for 7 days. Oral administration of free RFB showed clearance from plasma within 24 h. The relative bioavailability of RFB from SLNs was five fold higher as compared to administration with free RFB. The intent of using lipid nanocarriers is primarily to enhance the oral bioavailability of rifabutin and eventually decrease the dose and dosing frequency for successful management of MAC infection.

Optimization, in vitro-in vivo evaluation, and short-term tolerability of novel levofloxacin-loaded PLGA nanoparticle formulation.

A novel poly(lactic-co-glycolic acid) (PLGA)-based nanoformulation of levofloxacin was developed for multidrug-resistant tuberculosis with the purpose of achieving sustained release in plasma. After lyophilization of levofloxacin-loaded nanoparticles, the average size, charge, and polydispersity index were 268 ± 18 nm, -10.2 ± 1.5 mV, and 0.15 ± 0.03, respectively. The maximum drug encapsulation efficiency and loading capacity were 36.9 ± 6.1% (w/w) and 7.2 ± 1.2 mg/100 mg nanopowder, respectively. Biphasic extended-release profile was produced in vitro. Scanning electron microscopy and Fourier transform infrared studies showed spherical shape of drug-loaded nanoparticles and no drug-polymer interactions were observed. After single oral administration in mice, levofloxacin-loaded PLGA nanoparticles produced sustained release of levofloxacin for 4 days in plasma against 24 h for free levofloxacin. Levofloxacin was detected in organs (lung, liver, and spleen) for up to 4-6 days in case of levofloxacin-loaded nanoparticles, whereas free levofloxacin was cleared within 24 h. This novel formulation did not show any significant adverse effects on body weight and clinical signs in mice. No treatment-related changes were found in hematological and biochemical parameters and on histopathological evaluation. These results indicate the feasibility of development of an orally efficacious safe formulation of levofloxacin with sustained-release properties.

Development of an ultrasensitive polymerase chain reaction-amplified immunoassay based on mycobacterial RD antigens: implications for the serodiagnosis of tuberculosis.

Immuno-polymerase chain reaction (I-PCR) combines the versatility of enzyme-linked immunosorbent assay (ELISA) with the exponential amplification power of PCR. The present study was designed to detect antibodies to Mycobacterium tuberculosis complex-specific region of difference (RD) antigens, i.e., early secretory antigenic target-6, culture filtrate protein-10, culture filtrate protein-21, and mycobacterial protein from species tuberculosis-64, as well as antigens in pulmonary tuberculosis patients by I-PCR assay. We could detect ESAT-6 and other RD antigens up to 0.1 fg by I-PCR assay, thus resulting in 10(7) times higher sensitivity than that observed with ELISA. With paired sample analysis based on the detection of antibodies in serum and antigens in sputum of the same individual, the sensitivity of RD multi-antigen cocktail-based I-PCR assay was 72% in smear-negative cases and 91% in smear-positive cases of pulmonary tuberculosis with high specificity values. In extrapulmonary tuberculosis patients, higher sensitivity was observed by detecting cocktail of antigens by I-PCR assay as compared to sensitivity earlier observed in the same samples by ELISA.

In vitro physicochemical characterization and short term in vivo tolerability study of ethionamide loaded PLGA nanoparticles: potentially effective agent for multidrug resistant tuberculosis.

PURPOSE: To achieve prolonged drug release for the treatment of multidrug resistant tuberculosis and to improve the patient compliance, ethionamide loaded PLGA nanoparticles were developed. MATERIAL AND METHODS: They were developed by solvent evaporation method and optimized. The optimized formulation was subjected to various physico-chemical characterization, in vitro release studies and in vivo tolerability study. RESULTS AND DISCUSSION: There was no significant drug-polymer interaction and drug was encapsulated as crystalline form in nanoparticles. In vitro release was sustained up to 15 days in various media. Ethionamide loaded nanoparticles in mice did not reveal any statistically significant treatment related effects on body weight gain and clinical signs. Likewise, no treatment-related toxic effect was found in hematology, clinical chemistry and histopathology. Our results indicate the development of an orally effective safe formulation of ethionamide with sustained release property. CONCLUSION: Hence, ethionamide loaded nanoparticles offer excellent potential for further preclinical and clinical studies.

Pharmacokinetics and tissue distribution studies of orally administered nanoparticles encapsulated ethionamide used as potential drug delivery system in management of multi-drug resistant tuberculosis.

Sustained release nanoformulations of second line anti-tubercular drugs can help in reducing their dosing frequency and improve patient's compliance in multi-drug resistant tuberculosis (MDR TB). The objective of the current study was to investigate the pharmacokinetics and tissues distribution of ethionamide encapsulated in poly (DL-lactide-co-glycolide) (PLGA) nanoparticles. The drug loaded nanoparticles were 286 ± 26 nm in size with narrow size distribution, and zeta-potential was -13 ± 2.5 mV. The drug encapsulation efficiency and loading capacity were 35.2 ± 3.1%w/w and 38.6 ± 2.3%w/w, respectively. Ethionamide-loaded nanoparticles were administered orally to mice at two different doses and the control group received free (unencapsulated) ethionamide. Ethionamide-loaded PLGA nanoparticles produced sustained release of ethionamide for 6 days in plasma against 6 h for free ethionamide. The Ethionamide was detected in organs (lung, liver, and spleen) for up to 5-7 days in the case of encapsulated ethionamide, whereas free ethionamide was cleared within 12 h. Ethionamide-loaded PLGA nanoparticles exhibited significant improvement in pharmacokinetic parameters, i.e. C(max), t(max), AUC0₋∞, AUMC0₋∞, and MRT of encapsulated ethionamide as compared with free ethionamide. Drug in nanoparticles also exhibited a dose proportional increase in the AUC0₋∞ values. The pharmacodynamic parameters such as AUC0₋24/MIC, C(max)/MIC, and Time > MIC were also improved. PLGA nanoparticles of ethionamide have great potential in reducing dosing frequency of ethionamide in treatment of MDR TB.

Utility of a combination of RD1 and RD2 antigens as a diagnostic marker for tuberculosis.

We evaluated the diagnostic potential of a cocktail of 4 antigens encoded by regions of difference (RD) 1 and 2 of Mycobacterium tuberculosis, that is, early secretory antigenic target-6, culture filtrate protein-10 (CFP-10), CFP-21, and mycobacterial protein from species tuberculosis-64 (MPT-64) on the basis of antigen and antibody detection by enzyme-linked immunosorbent assay. Parallel detection of antigens and antibodies in the serum samples of pulmonary tuberculosis (PTB) patients resulted in higher sensitivity as compared to either of the single tests in both smear-positive (90%) and smear-negative (60%) PTB patients. In addition, combined detection of antigens and antibodies in the fluids of extrapulmonary tuberculosis (EPTB) patients could detect >90% of the patients with high specificity. These results demonstrate the ability of the combination of antigen and antibody detection assays based on the cocktail of RD antigens to diagnose a substantial number of PTB and EPTB cases with high specificity.