29 30 Running title: high dose rifampicin in tuberculous meningitis 31 Word count: running title: 46 characters; abstract: 199 words; main text: 3487 words 32 2 ABSTRACT 33 34 Background 35High doses of rifampicin may help tuberculous meningitis (TBM) patients to survive. Pharmacokinetic-36 pharmacodynamic evaluations suggested that rifampicin doses higher than 13 mg/kg intravenously or 20 mg/kg 37 orally (as previously studied) are warranted to maximize treatment response.
38
Methods
39In a double-blinded, randomised, placebo-controlled phase II trial, we assigned 60 adult TBM patients in 40 Bandung, Indonesia, to standard 450 mg, 900 mg or 1350 mg (10, 20 and 30 mg/kg) oral rifampicin combined 41 with other TB drugs for 30 days. Endpoints included pharmacokinetic measures, adverse events and survival.
42
Results
43A double and triple dose of oral rifampicin led to three and five-fold higher geometric mean total exposures in 44 plasma in the critical early days (21) of treatment (AUC 0-24h: 53·5 mg.h/L vs 170·6 mg.h/L vs. 293·5 mg.h/L, 45 p<0·001), with proportional increases in CSF concentrations and without an increase in the incidence of grade 46 3/4 adverse events. Six-month mortality was 7/20 (35%), 9/20 (45%) and 3/20 (15%) in the 10, 20 and 30 mg/kg 47 groups, respectively (p=0·12).
48
Conclusions
49Tripling the standard dose caused a large increase in rifampicin exposure in plasma and CSF and was safe.
50Survival benefit with this dose should now be evaluated in a larger phase III clinical trial. 51 52 53 54 55 In 2016, the WHO published data on 10.4 million new tuberculosis (TB) cases and 1·3 million deaths caused by 57 this disease worldwide, making it the leading single infectious disease killer.(1) In turn, tuberculous meningitis 58 (TBM) is the most devastating form of TB. It occurs in 1-6% of patients with TB,(2, 3) leading to death or 59 neurological disability in more than 30% of affected patients.(2, 4, 5) 60 Antimicrobial treatment for TBM follows the model for pulmonary TB, with intensive and continuation phases 61 of treatment. It adheres to the same first-line TB drugs and dosing guidelines,(6) although it is known that some 62 first-line TB drugs, including rifampicin, achieve suboptimal concentrations beyond the blood-brain and blood-63 cerebrospinal fluid (CSF) barriers. Rifampicin is a crucial TB drug, evidenced by the high mortality rate in TBM 64 patients with resistance to rifampicin.(7, 8) As it takes a long time to develop new drugs to treat TB and TBM, it 65is important to make the best possible use of existing drugs. We performed a series of studies to evaluate higher 66 doses of rifampicin in Indonesian patients with TBM.
67A first open-label, randomised phase II clinical trial showed that a 33% higher dose of rifampicin administered 68 intravenously (13 mg/kg iv) for two weeks led to a three-fold higher exposure to rifampicin in plasma and CSF 69 during the first critical days of treatment, and a strong reduction in mortality at six months after the treatment 70 started (adjust...