High doses of rifampin may help patients with tuberculous meningitis (TBM) to survive. Pharmacokinetic pharmacodynamic evaluations suggested that rifampin doses higher than 13 mg/kg given intravenously or 20 mg/kg given orally (as previously studied) are warranted to maximize treatment response. In a double-blind, randomized, placebo-controlled phase II trial, we assigned 60 adult TBM patients in Bandung, Indonesia, to standard 450 mg, 900 mg, or 1,350 mg (10, 20, and 30 mg/kg) oral rifampin combined with other TB drugs for 30 days. The endpoints included pharmacokinetic measures, adverse events, and survival. A double and triple dose of oral rifampin led to 3- and 5-fold higher geometric mean total exposures in plasma in the critical early days (2 ± 1) of treatment (area under the concentration-time curve from 0 to 24 h [AUC], 53.5 mg · h/liter versus 170.6 mg · h/liter and 293.5 mg · h/liter, respectively; < 0.001), with proportional increases in cerebrospinal fluid (CSF) concentrations and without an increase in the incidence of grade 3 or 4 adverse events. The 6-month mortality was 7/20 (35%), 9/20 (45%), and 3/20 (15%) in the 10-, 20-, and 30-mg/kg groups, respectively ( = 0.12). A tripling of the standard dose caused a large increase in rifampin exposure in plasma and CSF and was safe. The survival benefit with this dose should now be evaluated in a larger phase III clinical trial. (This study has been registered at ClinicalTrials.gov under identifier NCT02169882.).

Background Intensified antimicrobial treatment with higher rifampicin doses may improve outcome of tuberculous meningitis, but the desirable exposure and necessary dose are unknown. Our objective was to characterize the relationship between rifampicin exposures and mortality in order to identify optimal dosing for tuberculous meningitis. Methods An individual patient meta-analysis was performed on data from three Indonesian randomized controlled phase II trials comparing oral rifampicin 450mg (~10mg/kg) to intensified regimens including 750-1350mg orally, or a 600mg intravenous infusion. Pharmacokinetic data from plasma and CSF was analyzed with nonlinear mixed-effects modeling. Six-month survival was described with parametric time-to-event models. Results Pharmacokinetic analyses included 133 individuals (1150 concentration measurements, 170 from CSF). The final model featured two disposition-compartments, saturable clearance and autoinduction. Rifampicin CSF concentrations were described by a partition coefficient (5.5% [95%CI 4.4-6.4]) and half-life for distribution plasma to CSF (2.1 h [1.3-2.9]). Higher CSF protein concentration increased the partition coefficient. Survival of 148 individuals (58 died, 15 drop-outs) was well described by an exponentially declining hazard, with lower age, higher baseline Glasgow Coma Scale score and higher individual rifampicin plasma exposure reducing the hazard. Simulations predicted an increase in 6-month survival from ~50% to ~70% upon increasing the oral rifampicin dose from 10 to 30mg/kg, and that higher doses would further increase survival. Conclusions Higher rifampicin exposure substantially decreased the risk of death, and the maximal effect was not reached within the studied range. We suggest a rifampicin dose of at least 30mg/kg to be investigated in phase III clinical trials.

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ObjectiveTo assess the pharmacokinetics and safety/tolerability of isoniazid, rifampicin and pyrazinamide in children and adolescents with tuberculous meningitis (TBM).DesignProspective observational pharmacokinetic study with an exploratory pharmacokinetic/pharmacodynamic analysis.SettingHasan Sadikin Hospital, Bandung, Indonesia.PatientsIndividuals aged 0–18 years clinically diagnosed with TBM and receiving first-line anti-tuberculosis drug dosages according to revised WHO-recommended treatment guidelines.InterventionsPlasma and cerebrospinal fluid (CSF) concentrations of isoniazid, rifampicin and pyrazinamide were assessed on days 2 and 10 of treatment.Main outcome measuresPlasma exposures during the daily dosing interval (AUC0–24), peak plasma concentrations (Cmax) and CSF concentrations.ResultsAmong 20 eligible patients, geometric mean AUC0–24 of isoniazid, rifampicin and pyrazinamide was 18.5, 66.9 and 315.5 hour∙mg/L on day 2; and 14.5, 71.8 and 328.4 hour∙mg/L on day 10, respectively. Large interindividual variabilities were observed in AUC0–24 and Cmax of all drugs. All patients had suboptimal rifampicin AUC0–24 for TBM treatment indication and very low rifampicin CSF concentrations. Four patients developed grade 2–3 drug-induced liver injury (DILI) within the first 4 weeks of treatment, in whom anti-tuberculosis drugs were temporarily stopped, and no DILI recurred after reintroduction of rifampicin and isoniazid. AUC0–24 of isoniazid, rifampicin and pyrazinamide along with Cmax of isoniazid and pyrazinamide on day 10 were higher in patients who developed DILI than those without DILI (p<0.05).ConclusionHigher rifampicin doses are strongly warranted in treatment of children and adolescents with TBM. The association between higher plasma concentrations of isoniazid, rifampicin and pyrazinamide and the development of DILI needs confirmatory studies.

The pharmacokinetic (PK) and clinical implications of combining metformin with rifampicin are relevant to increasing numbers of patients with diabetic tuberculosis (TB) across the world and are yet unclear. We assessed the impact of rifampicin on metformin PKs and its glucose-lowering effect in patients with diabetic TB by measuring plasma metformin and blood glucose during and after TB treatment. Rifampicin increased metformin exposure: plasma area under the plasma concentration-time curve from time point 0 to the end of the dosing interval (AUC ) and peak plasma concentration (C ) geometric mean ratio (GMR; during vs. after TB treatment) were 1.28 (90% confidence interval (CI) 1.13-1.44) and 1.19 (90% CI 1.02-1.38; n = 22). The metformin glucose-lowering efficacy did not change (Δglucose - C ; P = 0.890; n = 18). Thus, we conclude that additional glucose monitoring in this population is not warranted. Finally, 57% of patients on metformin and rifampicin, and 38% of patients on metformin alone experienced gastrointestinal adverse effects. Considering this observation, we advise patients to take metformin and rifampicin with food and preferably separated in time. Clinicians could consider metoclopramide if gastrointestinal adverse effects occur.