Effects of pyridoxine on the intestinal absorption and pharmacokinetics of isoniazid in rats

Blutaparon portulacoides ethanolic extract reduced IL-1β and inflammatory parameters induced by the Mycobacterium complex and carrageenan in mice

Information on the health benefits of ethanolic extracts obtained from Blutaparon portulacoides stem (EEBP) hasn´t been consistently described in the literature until the present moment. This study investigated the antimycobacterial, anti-inflammatory and toxicological effects of EEBP in models of inflammation/infection, as well as its chemical composition. Chemical analysis of EEBP by electrospray ionization-mass spectrometry/HPLC-MS/MS identified 3,5,3'-Trihydroxy-4'-methoxy-6,7-methylenedioxy-flavone, gomphrenol, ferulic, vanillic, and caffeic acids. The minimum inhibitory concentration of EEBP and isoniazid in the presence of Mycobacterium tuberculosis was 123.4 and 0.030 µg/ml, respectively. EEBP oral administration (p.o.) (300-1000 mg/kg) or dexamethasone subcutaneous injection (s.c.) (1 mg/kg) significantly inhibited leukocytes and proteins resulting from carrageenan-induced pleurisy in Swiss mice. In the BCG-induced pleurisy model, the oral treatments performed once a day for 7 days, with EEBP (30 and 100 mg/kg) and isoniazid (25 mg/kg), inhibited the increase in plasmatic IL-1β levels and in pleural exudate from C57BL-6 mice, and reduced M. tuberculosis growth in organs (colony forming units assays). EEBP (30-300 mg/kg, p.o.) and dexamethasone (1 mg/s.c.) significantly prevented carrageenan-induced oedema and mechanical hyperalgesia in Swiss mice. The treatments (once a day for 22 days) with EEBP (30 mg/kg, p.o.) and dexamethasone (1 mg/s.c.) substantially inhibited oedema and mechanical- and cold-hyperalgesia at 11, 16 and 22 days after the administration of Freund's Complete Adjuvant in C57bL6 mice. No evidence of physio-pathologic was observed in Wistar rats acutely treated with EEBP (2000 mg/kg, p.o.). This study confirms the anti-inflammatory and antibiotic properties of EEBP, opening possibilities for the development of safe new drugs with dual anti-inflammatory/antimycobacterial activities which could be favorable from a pharmacoeconomic perspective.

Benefits of Therapeutic Drug Monitoring of First Line Antituberculosis Drugs

Tuberculosis is an airborne infectious disease that remains a huge global health-related issue nowadays. Despite constant approvals of newly developed drugs, the use of first-line antituberculosis medicines seems reasonable in drug-susceptible Mycobacterium tuberculosis strains. Therapeutic drug monitoring presents a useful technique for the determination of plasma drug concentration to adjust appropriate dose regimes. In tuberculosis treatment, therapeutic drug monitoring is aiding clinicians in selecting an optimal therapeutic level, which is essential for the personalisation of therapy. This review is aimed at clarifying the use of therapeutic drug monitoring of the first-line antituberculosis drugs in routine clinical practice.

A Physiologically Based Pharmacokinetic Model of Isoniazid and Its Application in Individualizing Tuberculosis Chemotherapy

Due to its high early bactericidal activity, isoniazid (INH) plays an essential role in tuberculosis treatment. Genetic polymorphisms of N-acetyltransferase type 2 (NAT2) cause a trimodal distribution of INH pharmacokinetics in slow, intermediate, and fast acetylators. The success of INH-based chemotherapy is associated with acetylator and patient health status. Still, a standard dose recommended by the FDA is administered regardless of acetylator type or immune status, even though adverse effects occur in 5 to 33% of all patients. Slow acetylators have a higher risk of development of drug-induced toxicity, while fast acetylators and immune-deficient patients face lower treatment success rates. To mechanistically assess the trade-off between toxicity and efficacy, we developed a physiologically based pharmacokinetic (PBPK) model describing the NAT2-dependent pharmacokinetics of INH and its metabolites. We combined the PBPK model with a pharmacodynamic (PD) model of antimycobacterial drug effects in the lungs. The resulting PBPK/PD model allowed the simultaneous simulation of treatment efficacies at the site of infection and exposure to toxic metabolites in off-target organs. Subsequently, we evaluated various INH dosing regimens in NAT2-specific immunocompetent and immune-deficient virtual populations. Our results suggest the need for acetylator-specific dose adjustments for optimal treatment outcomes. A reduced dose for slow acetylators substantially lowers the exposure to toxic metabolites and thereby the risk of adverse events, while it maintains sufficient treatment efficacies. Vice versa, intermediate and fast acetylators benefit from increased INH doses and a switch to a twice-daily administration schedule. Our analysis outlines how PBPK/PD modeling may be used to design and individualize treatment regimens.

Insights into the pharmacokinetic properties of antitubercular drugs

INTRODUCTION

The furiously advancing cases of multidrug-resistant tuberculosis (TB) along with the recent emergence of total drug resistant TB and TB-AIDS comorbidity present an increased threat to global public health. Knowledge of pharmacokinetic properties helps in selecting an appropriate anti-TB dosage regimen to achieve optimal results in patients.

AREAS COVERED

This article provides a brief compilation of the information available regarding published pharmacokinetic data for anti-TB drugs and may act as a single window for investigators/medical practitioners in this field. The information regarding absorption, tissue distribution, elimination and pharmacokinetic interactions of the first- and second-line anti-TB drugs and candidate drugs under clinical trials is discussed.

EXPERT OPINION

Pharmacokinetic properties such as poor absorption, too short biological half-life, extensive first-pass metabolism, drug-food and drug-drug related interactions are not attractive for prospective anti-TB drugs and significantly contribute to treatment failure and further resistance. The long duration, monotonous and multidrug treatment plan leads to poor patient compliance and resulted in a greater occurrence of anti-TB drug resistance worldwide. Few new agents, which are in development phase, are considering the aspect of shortening duration of the treatment regimen and provide a boost in therapy that is sorely needed.