Development of rifapentine susceptibility tests for Mycobacterium tuberculosis

An Overview of Various Rifampicin Analogs against Mycobacterium tuberculosis and their Drug Interactions

The success of the TB control program is hampered by the major issue of drug-resistant tuberculosis (DR-TB). The situation has undoubtedly been made more difficult by the widespread and multidrug-resistant (XDR) strains of TB. The modification of existing anti-TB medications to produce derivatives that can function on resistant TB bacilli is one of the potential techniques to overcome drug resistance affordably and straightforwardly. In comparison to novel pharmaceuticals for drug research and progress, these may have a better half-life and greater bioavailability, be more efficient, and serve as inexpensive alternatives. Mycobacterium tuberculosis, which is drugsusceptible or drug-resistant, is effectively treated by several already prescribed medications and their derivatives. Due to this, the current review attempts to give a brief overview of the rifampicin derivatives that can overcome the parent drug's resistance and could, hence, act as useful substitutes. It has been found that one-third of the global population is affected by M. tuberculosis. The most common cause of infection-related death can range from latent TB to TB illness. Antibiotics in the rifamycin class, including rifampicin or rifampin (RIF), rifapentine (RPT), and others, have a special sterilizing effect on M. tuberculosis. We examine research focused on evaluating the safety, effectiveness, pharmacokinetics, pharmacodynamics, risk of medication interactions, and other characteristics of RIF analogs. Drug interactions are especially difficult with RIF because it must be taken every day for four months to treat latent TB infection. RIF continues to be the gold standard of treatment for drug-sensitive TB illness. RIF's safety profile is well known, and the two medicines' adverse reactions have varying degrees of frequency. The authorized once-weekly RPT regimen is insufficient, but greater dosages of either medication may reduce the amount of time needed to treat TB effectively.

Chemotherapeutic interventions against tuberculosis

Tuberculosis is the second leading cause of infectious deaths globally. Many effective conventional antimycobacterial drugs have been available, however, emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) has overshadowed the effectiveness of the current first and second line drugs. Further, currently available agents are complicated by serious side effects, drug interactions and long-term administration. This has prompted urgent research efforts in the discovery and development of new anti-tuberculosis agent(s). Several families of compounds are currently being explored for the treatment of tuberculosis. This review article presents an account of the existing chemotherapeutics and highlights the therapeutic potential of emerging molecules that are at different stages of development for the management of tuberculosis disease.

Antimycobacterial activity of flavonoids from Lantana camara Linn

Linaroside (1) and lantanoside (2), two flavonoids isolated from Lantana camara and their common acetyl derivative (3) were examined for antimycobacterial activity against Mycobacterium tuberculosis, strain H(37)Rv. These compounds exhibited 30, 37 and 98% inhibition, respectively at 6.25 microg mL(-1) concentration. Among these flavonoids acetylated compound was found to be the most active.

Rapid determination of rifampin resistance in clinical isolates of Mycobacterium tuberculosis by real-time PCR

Real-time PCR was used to determine rifampin resistance in clinical isolates of Mycobacterium tuberculosis. Ninety-six rifampin-resistant isolates and 23 rifampin-susceptible isolates were included in the study. A 305-bp region covering the 81-bp "rifampin resistance-determining region" of rpoB was amplified. Two hybridization probe pairs that covered the most frequent mutation sites in rpoB, codon regions 526 to 531 and 513 to 516, were used. The results obtained by real-time PCR were compared to those obtained by the proportion method. For detection of rifampin resistance, the real-time PCR assay yielded a sensitivity of 92.7% and a specificity of 100%. Real-time PCR is a very rapid method, and it can be especially helpful for the reporting of resistant clinical isolates in a very short period of time.

Anti-HIV natural product (+)-calanolide A is active against both drug-susceptible and drug-resistant strains of Mycobacterium tuberculosis

Naturally occurring anti-HIV-1 agent (+)-calanolide A was found to be active against all of the strains of Mycobacterium tuberculosis tested, including those resistant to the standard antitubercular drugs. Efficacy evaluations in macrophages revealed that (+)-calanolide A significantly inhibited intracellular replication of M. tuberculosis H37Rv at concentrations below the MIC observed in vitro. Preliminary mechanistic studies indicated that (+)-calanolide A rapidly inhibits RNA and DNA synthesis followed by an inhibition of protein synthesis. Compared with known inhibitors, this scenario is more similar to effects observed with rifampin, an inhibitor of RNA synthesis. Since (+)-calanolide A was active against a rifampin-resistant strain, it is believed that these two agents may involve different targets. (+)-Calanolide A and its related pyranocoumarins are the first class of compounds identified to possess antimycobacterial and antiretroviral activities, representing a new pharmacophore for anti-TB activity.

Rapid detection of rifampin resistance in Mycobacterium tuberculosis isolates by heteroduplex analysis and determination of rifamycin cross-resistance in rifampin-resistant isolates

Direct heteroduplex analysis and a universal heteroduplex generator assay were performed to detect rifampin resistance rapidly in Turkish Mycobacterium tuberculosis isolates. Cross-resistance to rifapentine, rifabutin, and rifalazil was investigated. A relationship between specific mutations and resistance patterns, which can guide the choice of an appropriate therapeutic regimen for tuberculosis patients, was identified.

Single-dose intrapulmonary pharmacokinetics of rifapentine in normal subjects

The intrapulmonary pharmacokinetics of rifapentine were studied in 30 volunteers who received a single, oral dose of rifapentine (600 mg). Subgroups of five subjects each underwent bronchoscopy and bronchoalveolar lavage (BAL) at timed intervals following drug administration. Drug concentrations, including the concentration of the primary metabolite 25-desacetyl rifapentine, were determined in plasma, BAL fluid, and alveolar cells (AC) by high-pressure liquid chromatography. The concentrations in epithelial lining fluid (ELF) were calculated by the urea diffusion method. The concentration-time data were fit to two-compartment (plasma) or one-compartment (AC and ELF) models. The peak concentrations in plasma, ELF, and AC, 26.2, 3. 7, and 5.3 microg/ml, respectively, occurred at 5, 5, and 7 h after drug administration, respectively. The half-lives and areas under the curve for plasma, ELF, and AC were 18.3 h and 520 microg. h/ml, 20.8 h and 111 microg. h/ml, and 13.0 h and 133 microg. h/ml, respectively. Although the intrapulmonary rifapentine concentrations were less than the plasma rifapentine concentrations at all time periods, they remained above the proposed breakpoint for M. tuberculosis (0.5 microg/ml) for the 48-h observation period. These data provide a pharmacokinetic rationale for extended-interval dosing. The optimum dosing regimen for rifapentine will have to be determined by controlled clinical trials.

Synthesis and in vitro anti-mycobacterium activity of N-alkyl-1, 2-dihydro-2-thioxo-3-pyridinecarbothioamides. Preliminary toxicity and pharmacokinetic evaluation

Disseminated infections with Mycobacterium tuberculosis (MT) and Mycobacterium avium complex (MAC) are increasingly opportunistic diseases in patients with advanced acquired human immunodeficiency syndrome (AIDS). A series of N-alkyl-1, 2-dihydro-2-thioxo-3-pyridinecarbothioamides has been synthesized, and MICs for MT and MAC strains, either standard or isolated from infected patients, have been determined. Preliminary tests show a good activity and a very low toxicity for some derivatives. Pharmacokinetic studies in the rat show a very rapid elimination from the body after intravenous administration and a poor absorption after oral administration.