Phase 1 Study of the Effects of the Tuberculosis Treatment Pretomanid, Alone and in Combination With Moxifloxacin, on the QTc Interval in Healthy Volunteers

Multidrug-resistant tuberculosis

Tuberculosis (TB) remains the foremost cause of death by an infectious disease globally. Multidrug-resistant or rifampicin-resistant TB (MDR/RR-TB; resistance to rifampicin and isoniazid, or rifampicin alone) is a burgeoning public health challenge in several parts of the world, and especially Eastern Europe, Russia, Asia and sub-Saharan Africa. Pre-extensively drug-resistant TB (pre-XDR-TB) refers to MDR/RR-TB that is also resistant to a fluoroquinolone, and extensively drug-resistant TB (XDR-TB) isolates are additionally resistant to other key drugs such as bedaquiline and/or linezolid. Collectively, these subgroups are referred to as drug-resistant TB (DR-TB). All forms of DR-TB can be as transmissible as rifampicin-susceptible TB; however, it is more difficult to diagnose, is associated with higher mortality and morbidity, and higher rates of post-TB lung damage. The various forms of DR-TB often consume >50% of national TB budgets despite comprising <5-10% of the total TB case-load. The past decade has seen a dramatic change in the DR-TB treatment landscape with the introduction of new diagnostics and therapeutic agents. However, there is limited guidance on understanding and managing various aspects of this complex entity, including the pathogenesis, transmission, diagnosis, management and prevention of MDR-TB and XDR-TB, especially at the primary care physician level.

Safety and pharmacokinetic profile of pretomanid in healthy Chinese adults: Results of a phase I single dose escalation study

We investigated the safety, tolerability and pharmacokinetic (PK) profile of pretomanid (formerly PA-824) in healthy Chinese volunteers. This was a single-center, double-blind, placebo-controlled, phase I dose escalation study, in which healthy volunteers were consecutively allocated to increasing pretomanid dose groups (50, 100, 200, 400, 600, 800, or 1000 mg) and randomized to receive pretomanid or matching placebo. The primary objective was to evaluate the safety, tolerability and PK profile of pretomanid. In total, 306 volunteers were screened, and 60 were assigned to treatment (pretomanid: n = 46, placebo: n = 14) of whom 83.3% were male, age ranged from 19 to 39 years and BMI ranged from 19.2 to 25.9 kg/m². At least one adverse event (AE) was reported by 67.4% of subjects assigned to pretomanid and 50.0% of those who received placebo, there were no serious AEs or AEs leading to withdrawal. Drug-related events that occurred in ≥5% of participants assigned to pretomanid were proteinuria (26.1%), insignificant microscopic hematuria (15.2%), conjugated hyperbilirubinemia (6.5%), hyperbilirubinemia (6.5%) and elevated uric acid (6.5%). No relationship between pretomanid dose and AEs was observed. In the PK analysis (n = 46), maximum pretomanid plasma concentration was reached in a median of 4 h in all dose groups except 800 mg (12 h) and the plasma half-life ranged from 20.2 to 25.2 h. No dose proportionality was observed for maximum plasma concentration, or area under the plasma concentration curve. In conclusion, single pretomanid doses from 50 to 1000 mg were well tolerated in healthy Chinese participants and the PK profile was generally consistent with findings in non-Chinese populations.

Toxicity and toxicokinetic assessment of an anti-tubercular drug pretomanid in cynomolgus monkeys

Pretomanid is a nitroimidazooxazine antimycobacterial drug that was approved in more than 10 countries as part of a three-drug, all oral regimen, consisting of bedaquiline, pretomanid, and linezolid (BPaL) for 6-months treatment of adults with pulmonary extensively drug-resistant tuberculosis (XDR-TB) or with complicated forms of multidrug-resistant tuberculosis (MDR-TB). The toxicological profile of pretomanid was thoroughly evaluated in repeat-dose oral toxicity studies up to 39 weeks long in cynomolgus monkeys. Exposures up to 10-fold higher than in humans at the approved pretomanid dose (200 mg) were achieved in acute studies allowing for characterization of dose-limiting toxicity. Target organs and processes identified in acute and chronic toxicity studies included QT prolongation, nervous system effects, and liver effects (minimal hepatocellular hypertrophy without elevations in liver enzymes). In a 13-week study, no cataracts were present at the end of dosing, but 2 of 12 monkeys had cataracts at the end of a 13-week recovery period. No cataracts related to pretomanid administration were observed in subsequent 13-week or 39-week studies. No male reproductive toxicity was observed in these studies. No-observed-adverse-effect levels (NOAELs) were identified in all studies. Exposures at the NOAELs equaled, or exceeded, human exposure at the approved pretomanid dose with the exception of female monkeys in a 39-week chronic toxicity study. These data support the use of pretomanid as part of the 6-month BPaL regimen for treating XDR-TB and MDR-TB.

Pretomanid for tuberculosis treatment: an update for clinical purposes

Coronavirus disease (COVID-19) pandemic determined a 10 years-set back in tuberculosis (TB) control programs. Recent advances in available therapies may help recover the time lost. While Linezolid (LZD) and Bedaquiline (BDQ), previously Group D second line drugs (SLDs) for TB, have been relocated to Group A, other drugs are currently being studied in regimens for drug resistant TB (DR-TB). Among these, Pretomanid (PA), a recently introduced antimycobacterial drug derived from nitroimidazole with both solid bactericidal and bacteriostatic effect, and with an excellent effectiveness and tolerability profile, is in the spotlight. Following promising data obtained from recently published and ongoing randomized controlled trials (RCTs), the World Health Organization (WHO) determined to include PA in its guidelines for the treatment of rifampicin-resistant (RR), multi drug resistant (MDR) and pre-extensively drug resistant TB (pre-XDR-TB) with BDQ, LZD and Moxifloxacine (MFX) in a 6-month regimen. Although further studies on the subject are needed, PA may also represent a treatment option for drug-susceptible TB (DS-TB), latent TB infection (LTBI) and non tuberculous mycobacteria (NTM). This narrative review aims to examine current implementation options and future possibilities for PA in the never-ending fight against TB.