Antimycobacterial susceptibility evaluation of rifampicin and isoniazid benz-hydrazone in biodegradable polymeric nanoparticles against <em>Mycobacterium tuberculosis</em> H37Rv strain

Abstract

IntroductionTuberculosis (TB) is the single largest infectious disease which requires a prolonged treatment regime with multiple drugs. The present treatment for TB includes frequent administration of a combination of four drugs for a duration of 6 months. This leads to patient’s noncompliance, in addition to developing drug-resistant strains which makes treatment more difficult. The formulation of drugs with biodegradable polymeric nanoparticles (NPs) promises to overcome this problem.Materials and methodsIn this study, we focus on two important drugs used for TB treatment – rifampicin (RIF) and isoniazid (INH) – and report a detailed study of RIF-loaded poly lactic-co-glycolic acid (PLGA) NPs and INH modified as INH benz-hydrazone (IH2) which gives the same therapeutic effect as INH but is more stable and enhances the drug loading in PLGA NPs by 15-fold compared to INH. The optimized formulation was characterized using particle size analyzer, scanning electron microscopy and transmission electron microscopy. The drug release from NPs and stability of drug were tested in different pH conditions.ResultsIt was found that RIF and IH2 loaded in NPs release in a slow and sustained manner over a period of 1 month and they are more stable in NPs formulation compared to the free form. RIF- and IH2-loaded NPs were tested for antimicrobial susceptibility against Mycobacterium tuberculosis H37Rv strain. RIF loaded in PLGA NPs consistently inhibited the growth at 70% of the minimum inhibitory concentration (MIC) of pure RIF (MIC level 1 µg/mL), and pure IH2 and IH2-loaded NPs showed inhibition at MIC equivalent to the MIC of INH (0.1 µg/mL).ConclusionThese results show that NP formulations will improve the efficacy of drug delivery for TB treatment.

Nanomedicines towards targeting intracellular Mtb for the treatment of tuberculosis

“…Literature on using nanomedicines to target TB is predominantly based on the use of polymers or liposomes with first‐line drugs RIF or INH. (Pandey et al, ; Pandey and Khuller, ; Pandey and Khuller, ; Ohashi et al, ; Hirota et al, ; Aboutaleb et al, ; Raj et al, ; Chuan et al, ; Dube et al, ; Vieira et al, ; Hakkimane et al, ) Studies have highlighted the possibilities of encapsulating anti‐TB drugs within biodegradable polymer NPs, thus increasing the concentration of drugs at specific sites (e.g., infected macrophages) through targeting. NPs containing anti‐TB drugs are usually made from biodegradable materials (e.g., alginate or solid lipids), and most TB research focuses on the use of poly‐lactic‐ co ‐glycolic acid (PLGA) synthetic polymers.…”

“…prepared nano‐formulations of PLGA NPs loaded with RIF and IH2 (INH modified into INH benz‐hydrazone). (Hakkimane et al, ) The characterization of the NPs shape and morphology was analyzed using Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) was employed to visualize the encapsulation of drugs inside the NPs. Reversed‐phase High Performance Liquid Chromatography (HPLC) was used to calculate the exact amount of drug encapsulated, and NP stability tests using dynamic light scattering were undertaken at different pH levels.…”

“…Reversed‐phase High Performance Liquid Chromatography (HPLC) was used to calculate the exact amount of drug encapsulated, and NP stability tests using dynamic light scattering were undertaken at different pH levels. (Hakkimane et al, ) Dynamic light scattering measures hydrodynamic diameter, the size of primary particles if dispersed, or agglomerates along with the shell of ions/water molecules associated with the surface, by measuring the scattered light that passes through a solution. The zeta potential, a measure of the charge carried by NPs when suspended in an aqueous environment, gives an indication of the stability of NPs in a solution.…”

“…After 24 h, 70% (pH 4.5) and 50% of RIF had degraded (pH 7.4), whereas when encapsulated, drug was released in a profoundly slower, sustained process over a period of days. (Hakkimane et al, ) Mycobacterial susceptibility tests were carried out using the traditional MGIT™ system(Tortoli et al, ) against the Mtb laboratory strain H37Rv. As growing Mtb utilize oxygen, the MGIT™ 960 system records the level of oxygen depletion via fluorescence readings, thus indicating both mycobacterial presence and growth.…”

“…Comparing RIF‐loaded PLGA NPs with native RIF drug, the authors report that at a concentration of 0.70 μg/mL, H37Rv developed resistance to native RIF but remained sensitive to RIF PLGA NPs, in which 100% inhibited bacilli growth. (Hakkimane et al, )…”