pharmacokinetics and safety/tolerability of isoniazid

70 Ruslami R, et al. Arch Dis Child 2022;107:70–77. doi:10.1136/archdischild-2020-321426

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Original research

Pharmacokinetics and safety/tolerability of isoniazid, rifampicin and pyrazinamide in children and adolescents treated for tuberculous meningitisRovina Ruslami,1 Fajri Gafar ,2 Vycke Yunivita,1 Ida Parwati,3 Ahmad R Ganiem,4 Rob E Aarnoutse,5 Bob Wilffert,2,6 Jan- Willem C Alffenaar,7,8 Heda M Nataprawira9

To cite: Ruslami R, Gafar F, Yunivita V, et al. Arch Dis Child 2022;107:70–77.

► Additional supplemental material is published online only. To view, please visit the journal online (http:// dx. doi. org/ 10. 1136/ archdischild- 2020- 321426).

For numbered affiliations see end of article.

Correspondence toFajri Gafar, Unit of PharmacoTherapy, -Epidemiology and -Economics, Groningen Research Institute of Pharmacy, University of Groningen, Groningen 9713 AV, The Netherlands; f. gafar@ rug. nl; fajri. gafar@ gmail. com

RR and FG contributed equally.

Received 14 December 2020Accepted 14 June 2021Published Online First 28 June 2021

► http:// dx. doi. org/ 10. 1136/ archdischild- 2021- 322660

Drug therapy

© Author(s) (or their employer(s)) 2022. Re- use permitted under CC BY. Published by BMJ.

ABSTRACTObjective To assess the pharmacokinetics and safety/tolerability of isoniazid, rifampicin and pyrazinamide in children and adolescents with tuberculous meningitis (TBM).Design Prospective observational pharmacokinetic study with an exploratory pharmacokinetic/pharmacodynamic analysis.Setting Hasan Sadikin Hospital, Bandung, Indonesia.Patients Individuals aged 0–18 years clinically diagnosed with TBM and receiving first- line antituberculosis drug dosages according to revised WHO- recommended treatment guidelines.Interventions Plasma and cerebrospinal fluid (CSF) concentrations of isoniazid, rifampicin and pyrazinamide were assessed on days 2 and 10 of treatment.Main outcome measures Plasma exposures during the daily dosing interval (AUC0–24), peak plasma concentrations (Cmax) and CSF concentrations.Results Among 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 antituberculosis 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).Conclusion Higher 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.

INTRODUCTIONTuberculosis (TB) remains a major global health challenge with 1.2 million new paediatric cases and >220 000 deaths in children aged <15 years.1 Tuberculous meningitis (TBM), as the most devas-tating manifestation of TB, accounts for approxi-mately 20% of childhood TB mortality and results in neurological sequelae in more than 50% of survi-vors.2 3 Management of TBM poses continuing

challenges, mainly due to the lack of understanding of the pathogenesis, a lengthy process in obtaining a definite diagnosis and suboptimal antimicro-bial drug therapy.3 Delayed or late presentation of TBM is a major problem associated with worse outcomes.2

First- line anti- TB drug doses for treatment of children with TBM were revised by the WHO in 20104 and are similar to those described for chil-dren with pulmonary TB (PTB).4 5 Following this revised dosing, sufficient plasma concentrations of isoniazid, rifampicin and pyrazinamide in children aged <2 years were reported.6 However, subther-apeutic concentrations are still shown in high proportions of patients, particularly among young children for rifampicin and pyrazinamide7–9 and among fast acetylators for isoniazid.8 Furthermore, rifampicin and ethambutol have poor cerebrospinal fluid (CSF) penetration,10 11 which in case of TBM might lead to subtherapeutic concentrations at the site of infection. As an alternative TBM treatment option in children, the WHO suggests high- dose short- course therapy using isoniazid, rifampicin and pyrazinamide, with addition of ethionamide instead of ethambutol.5 10 12

What is already known on this topic?

► Pharmacokinetic data of antituberculosis (TB) drugs in children with tuberculous meningitis (TBM), particularly among the Indonesian paediatric population are lacking.

► Suboptimal or toxic concentrations of anti- TB drugs contribute to unfavourable treatment outcomes.

What this study adds?

► Suboptimal plasma exposures and very low cerebrospinal fluid concentrations of rifampicin were observed in all patients; higher doses for this pivotal drug are strongly warranted.

► The association between higher plasma concentrations of isoniazid, rifampicin and pyrazinamide and the development of drug- induced liver injury during TBM treatment needs confirmatory studies.

on July 24, 2022 by guest. Protected by copyright.

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71Ruslami R, et al. Arch Dis Child 2022;107:70–77. doi:10.1136/archdischild-2020-321426

Original research

Drug therapy

Pharmacokinetic (PK) data of anti- TB drugs in children with TBM are lacking. PK evaluation of first- line anti- TB drugs is important because suboptimal concentrations might lead to unfavourable outcomes such as treatment failure and death.13 On the contrary, exposure to supratherapeutic concentrations might play a role in increasing the risk of adverse effects, like anti- TB drug- induced liver injury (DILI).14 We aimed to describe PK and safety/tolerability of isoniazid, rifampicin and pyrazin-amide in Indonesian children and adolescents treated for TBM.

METHODSStudy design and populationWe performed a prospective observational PK and safety/toler-ability study with an exploratory pharmacokinetic/pharmacody-namic (PK/PD) analysis in children and adolescents aged ≤18 years at Hasan Sadikin Hospital, Bandung, Indonesia, from March 2018 to January 2020. Written informed consent for study participation was obtained from parents/legal guardians, with additional verbal consent/assent from competent children aged >12 years.

Initial screening among those with suspected meningitis included physical and clinical examinations, blood chemistry and haematology measurements, chest radiography and CSF analysis. Neuroradiology and microbiological examination from CSF/extraneural samples including smear microscopy for acid- fast bacilli, culture for Mycobacterium tuberculosis and GeneX-pert MTB/RIF assay were performed, if applicable. In our setting, neuroradiology and GeneXpert testing during screening are not covered by government health insurance. Patients with definite TBM (microbiologically proven from CSF examination), and those clinically diagnosed with probable/possible TBM as deter-mined by case definition criteria,15 were eligible for inclusion in this study. Our exclusion criteria were mixed bacterial menin-gitis, taking anti- TB drugs ≥3 days, HIV co- infection, baseline alanine/aspartate aminotransferases (ALT/AST) >3× the ULN (reference ranges for ALT: 16–63 U/L and AST: 15–37 U/L) and medical conditions not allowing for inclusion according to the attending physician (eg, ventriculoperitoneal shunt, rapid clin-ical deterioration, kidney disease or autoimmune disorders).

TreatmentTreatment regimens were based on the current WHO guidelines in accordance with the Indonesian Paediatric Society guide-lines for TBM treatment in children, consisting of daily isoni-azid (7–15 mg/kg), rifampicin (10–20 mg/kg), pyrazinamide (30–40 mg/kg) and ethambutol (15–25 mg/kg) for a 2- month intensive phase, followed by a 10- month continuation phase of isoniazid and rifampicin at the same doses.5 16 All patients (including those weighing >25 kg) received dispersible fixed- dose combinations of isoniazid/rifampicin/pyrazinamide at 50/75/150 mg, with addition of ethambutol in a separate tablet. All anti- TB drugs (Kimia Farma, Indonesia) were taken orally on an empty stomach under directly observed treatment. For unconscious patients, the drugs were dissolved in water delivered through a nasogastric tube and flushed afterwards. A rifampicin formulation of the same manufacturer has shown bioavailability in adults equal to the international reference.17 Patients were given adjunctive oral prednisone (2–4 mg/kg) for the first 4–8 weeks, tapered according to the national guidelines.16

PK assessmentsPK sampling was performed on days 2±1 and 10±1 of treat-ment. Serial venous blood samples were collected at 0, 1, 2, 4

and 8 hours postdose; one CSF sample was also collected at 0–2, 3–5 or 6–8 hours postdose. Patients had an overnight fast from 23:00 hours on the day preceding PK assessments until 2 hours after drug administration. Bioanalysis was performed using a validated ultra- performance liquid chromatography method.18 PK parameters were assessed noncompartmentally using the PKNCA package V.0.9.4 in R for Windows. Main PK parameters were area under the plasma concentration–time curve during the daily dosing interval (AUC0–24), peak plasma concentration (Cmax) and CSF concentration (CCSF0–8). Further details are given in online supplemental appendix 1.

Follow-up and clinical responsesInpatient assessments were performed on days 3, 7, 10 and 14 of treatment, including physical examinations, Glasgow Coma Scale, anthropometry, vital signs and complications such as hypo-natraemia, decreased consciousness, new focal neurological signs and suspicion of DILI. Additional assessments were performed, if necessary. Liver function tests (LFTs) were measured on days 7 and 14 of treatment and were subsequently measured if symp-tomatic DILI was suspected. DILI was defined as an elevation of ALT/AST>3× the ULN with symptoms of hepatotoxicity (eg, jaundice, vomiting, nausea and abdominal pain) or >5× the ULN without the presence of symptoms.19 The severity of DILI was classified based on the common terminology criteria for adverse events (CTCAE V.5.0; https:// evs. nci. nih. gov/ ftp1/ CTCAE). Outcome of hospitalisation included good recovery, moderate and severe disabilities, persistent vegetative state and death. Six- month mortality was monitored by phone calls.

Statistical analysisOn the basis of the results from a previous study in adult patients with TBM,20 a minimum of 20 patients were judged to be suffi-cient to describe PK of anti- TB drugs. Actual target values for rifampicin AUC0–24 in TBM (171 or 229 hour∙mg/L) were based on a PK/PD analysis in Indonesian adults with TBM,21 and the proportion of patients achieving these target values was assessed. PK parameters on both sampling days were compared using a paired- sample t- test or Wilcoxon signed- rank test. Pearson correlation coefficients were used to assess the relationship between AUC0–24, Cmax and CCSF0–8. Predictors of drug exposures were evaluated using univariate and multivariate linear regres-sion analyses; more details are given in online supplemental appendix 2. AUC0–24 and Cmax values between DILI and non- DILI patients and between those who survived and died during the 6- month follow- up were compared using the Mann- Whitney U test. Data were analysed using SPSS Statistics (V.25.0; IBM).

RESULTSBetween March 2018 and July 2019, 81 suspected cases of paediatric TBM (39 (48%) aged <5 years) were screened, of whom 61 were excluded due to various reasons (online supple-mental appendix 3). Among 20 eligible HIV- negative patients with probable/possible TBM, 11 (55%) were female, 5 (25%) aged <5 years and 12 (60%) had grade 2 TBM. Baseline charac-teristics of the study population are presented in table 1.

Plasma concentration–time profiles of isoniazid, rifampicin and pyrazinamide are presented in figure 1. Geometric mean AUC0–24 of isoniazid, rifampicin and pyrazinamide on day 2 was 18.5, 66.9 and 315.5 hour∙mg/L, respectively. Large inter-individual variabilities were observed in AUC0–24 and Cmax of all drugs. None of the patients had achieved the target values of 229 or 171 hour∙mg/L for rifampicin AUC0–24. All patients had


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disproportionately lower rifampicin concentrations in CSF than in plasma (geometric mean CCSF0–8: 0.3 and 0.1 mg/L on days 2 and 10, respectively). Isoniazid and pyrazinamide concen-trations in CSF were relatively comparable to those in plasma. AUC0–24 and Cmax between both sampling days were not statisti-cally different (table 2). Additional PK parameters are presented in online supplemental appendix 4.

For each drug, AUC0–24 was highly correlated with Cmax (rs≥0.7; p<0.001). AUC0–24 and Cmax were also correlated with CCSF0–8 (rs≥0.5; p<0.05) (online supplemental appendix 5. Results of the univariate analyses for predictors of AUC0–24, Cmax and CCSF0–8 are presented in online supplemental appendix 6. In multivar-iate analyses, higher drug doses in mg/kg were associated with a larger increase in pyrazinamide Cmax (p<0.05); drug adminis-tration through a nasogastric tube was associated with a higher isoniazid AUC0–24 (p<0.01); and higher random blood glucose levels were associated with reduced pyrazinamide AUC0–24, Cmax and CCSF0–8 (p<0.01) (table 3).

During hospitalisation, two patients had grade 2 and two patients had grade 3 DILI. Of these, one developed DILI after 1 week of treatment, two after 2 weeks and one after 4 weeks. Jaundice was observed in two patients: one with grade 2 and one with grade 3 DILI. Isoniazid, rifampicin and pyra-zinamide were immediately stopped in these four patients. As per local guidelines, ethambutol was continued, with addition of streptomycin (15–40 mg/kg) for a maximum of 2 weeks. After the symptoms of DILI and liver enzymes had normalised,

Table 1 Baseline characteristics and drug doses of Indonesian children with TBM

Characteristics Value

Total cases, n 20

Female sex (n (%)) 11 (55.0)

Age, years (median (IQR)) 11.4 (4.4–14.7)

Age (n (%))

<5 years 5 (25.0)

5–9 years 4 (20.0)

10–14 years 6 (30.0)

15–18 years 5 (25.0)

BCG- vaccinated (n (%)) 11 (55.0)

Nutritional status*

Weight for age Z- score (median (IQR))† −2.08 (−3.06 to −1.32)

Height for age Z- score (median (IQR)) −2.10 (−2.44 to −1.21)

BMI for age Z- score (median (IQR)) −2.22 (−2.98 to −1.02)

Head circumference, cm (median (IQR)) 50.0 (45.6–52.2)

Upper arm circumference, cm (median (IQR)) 16.2 (12.6–20.6)

Abdominal circumference, cm (median (IQR)) 52.5 (46.7–58.2)

Malnourished, n (%) 14 (70.0)

Temperature, °C (median (IQR)) 37.1 (37.0–37.8)

Chief complaint (n (%))

Severe headache 3 (15.0)

Seizures 4 (20.0)

Decreased consciousness 9 (45.0)

Others 4 (20.0)

Diagnostic score (median (IQR))‡ 10.5 (10.0–12.0)

GCS (median (IQR)) 13.0 (11.0–15.0)

Chest radiography, suggestive TB (n (%)) 8 (40.0)

TBM category

Possible TBM 2 (10.0)

Probable TBM 18 (90.0)

TBM grade (n (%))§

Grade 1 4 (20.0)

Grade 2 12 (60.0)

Grade 3 4 (20.0)

CSF baselines (median (IQR))

Leucocytes, cells/µL 88.0 (41.0–134.2)

PMN, cells/µL 20.5 (5.0–43.7)

MN, cells/µL 79.5 (56.2–95.0)

Protein, mg/dL 176.9 (80.7–287.5)

CSF/blood glucose ratio (median (IQR)) 0.17 (0.10–0.44)

CSF smear microscopy (n (%))

Negative 15 (75.0)

Not tested 5 (25.0)

Cerebral imaging, done (n (%))¶ 12 (60.0)

Abnormal 11 (55.0)

Hydrocephalus 7 (35.0)

Basal meningeal enhancement 4 (20.0)

Brain oedema 4 (20.0)

Midline shift 2 (10.0)

Tuberculoma 1 (5.0)

Infarct 1 (5.0)

Intracerebral haemorrhage 1 (5.0)

Normal 1 (5.0)

GeneXpert MTB/RIF testing (extraneural), done (n (%))** 4 (20.0)

M.tb detected, susceptible to rifampicin 3 (15.0)

M.tb not detected 1 (5.0)

Continued

Characteristics Value

Blood test values (median (IQR))

Creatinine, mg/dL 0.5 (0.3–0.6)

Albumin, g/dL 3.2 (2.4–3.5)

Protein, g/dL 7.6 (6.9–8.4)

Random blood glucose, mg/dL 107.0 (102.0–119.0)

AST, IU/L 22.0 (16.0–33.0)

ALT, IU/L 16.0 (13.0–30.0)

Drug administration through NGT on PK1 (n (%)) 14 (70.0)

Drug administration through NGT on PK2 (n (%)) 4/12 (20.0)

Daily drug doses on PK1 (median (IQR))

Isoniazid (mg/kg) 8.9 (7.7–11.0)

Rifampicin (mg/kg) 13.4 (11.6–16.4)

Pyrazinamide (mg/kg) 26.7 (23.1–32.9)

Ethambutol (mg/kg) 20.5 (19.1–21.6)

*Anthropometric data were transformed into weight- for- age, height- for- age and BMI- for- age Z- scores based on the WHO standard reference populations using the R package ‘zscorer’ V.0.3.1. Malnutrition was defined as children aged <5 years with weight- for- age or height- for- age Z- scores <−2 SD and children aged ≥5 years with height- for- age or BMI- for- age Z- scores <−2 SD.†Weigh for age Z- score can only be calculated for nine children.‡Diagnostic score was assessed using a uniform case definition criteria for TBM by Marais et al.15

§Severity of TBM was classified according to the modified British Medical Research Council grading system as 1 (GCS of 15 with no focal neurological signs), 2 (GCS of 11–14 or 15 with focal neurological signs) or 3 (GCS<10).44

¶During hospitalisation, head computed tomographic scan was performed in 11 (55%) of 20 patients and head magnetic resonance imaging was performed in 1 (5%) of 20 patients.**Three patients were susceptible to rifampicin using GeneXpert testing from gastric lavage sample, and one patient had no M. tb detected in sputum sample.ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; CSF, cerebrospinal fluid; GCS, Glasgow Coma Scale; MN, mononuclear cells; NGT, nasogastric tube; PK1 and PK2, first and second pharmacokinetic sampling assessments; PMN, polymorphonuclear cells; TBM, tuberculous meningitis.

Table 1 Continued


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rifampicin and isoniazid were reintroduced gradually without any DILI recurrence. Pyrazinamide was completely stopped until the end of treatment. Isoniazid, rifampicin and pyrazin-amide doses were slightly higher in patients with DILI but not statistically different from those without DILI (p>0.05; online supplemental appendix 7). AUC0–24 of isoniazid, rifampicin and pyrazinamide, along with Cmax of isoniazid and pyrazinamide on day 10 were significantly higher in patients with DILI than those without DILI (p<0.05) (figure 2; online supplemental appendix 7).

At hospital discharge, 10 patients had good recovery, 2 were moderately disabled, 2 were severely disabled and 6 died due to increased intracranial pressure (n=2), intracerebral haem-orrhage (n=1), septic shock (n=1), respiratory failure (n=1) and hospital- acquired pneumonia (n=1). Within the 6- month follow- up, another patient died of unknown cause and the remaining 13 patients survived including those who previ-ously developed DILI. Post- mortem autopsy was unavailable to provide accurate causes of death. AUC0–24, Cmax and CCSF0–8 of isoniazid, rifampicin and pyrazinamide were not statistically different between patients who survived and died within the 6- month follow- up.

DISCUSSIONThis study presents important information on plasma and CSF concentrations of first- line anti- TB drugs in children and adoles-cents with TBM from Indonesia. Our average AUC0–24 values on day 2 of treatment compared with those reported in Indo-nesian adults with TBM were relatively similar for isoniazid (18.5 vs 16.4 hour∙mg/L),22 were higher for rifampicin (66.9 vs 53.5 hour∙mg/L)20 and were lower for pyrazinamide (315.5 vs 709 hour∙mg/L).23 Our results showed large interindividual variabilities in drug exposures, which are in agreement with the literature and might be enhanced by PK changes in critically ill patients.24 25 Furthermore, the wide age range included in this study from infants to adolescents, and the small sample size, might contribute to these large variabilities. Although none of our patients had diabetes mellitus, higher blood glucose levels were found to be associated with decreased pyrazinamide expo-sures. A hyperglycaemic condition may have reduced gastric mucosal blood flow and gastric acid secretion,26 which resulted in decreased absorption of anti- TB drugs.

The low rifampicin CSF concentration has been reported in Vietnamese children11 and in Indonesian adults with TBM.18 20 27 Likely the high plasma protein binding and blood- CSF/brain

Figure 1 Pharmacokinetic profiles (drug concentration vs time curves) of isoniazid (INH), rifampicin (RIF) and pyrazinamide (PZA) in children and adolescents treated for tuberculous meningitis on days 2 and 10 of treatment. (A) INH in plasma; (B) RIF in plasma; (C) PZA in plasma; (D) INH in cerebrospinal fluid (CSF); (E) RIF in CSF; (F) PZA in CSF.


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barrier efflux pumps can explain this low CSF rifampicin concen-tration.28 The bactericidal effect of such a low concentration, when compared with the minimum inhibitory concentration (MIC) of this drug against M. tuberculosis, is likely to be limited if we use plasma- derived fAUC/MIC or fCmax/MIC targets. In

adults, a 33% higher dose of intravenous rifampicin resulted in a threefold increase in plasma and CSF exposures compared with the standard dose of oral rifampicin.27 Threefold and fivefold increases in plasma exposure with proportional increases in CSF concentrations were also observed in adults given double and triple doses of oral rifampicin.20 It seems that efflux pumps may be saturable and CSF rifampicin concentrations can be enhanced by increasing the dose. In South African children, short- course intensified TBM treatment with isoniazid (20 mg/kg), rifampicin (20 mg/kg), pyrazinamide (40 mg/kg) and ethionamide (20 mg/kg) was found to be safe and effective.12 Intensified regimens containing high- dose rifampicin and other anti- TB drugs with better CSF penetration (eg, fluoroquinolones and ethionamide), along with ancillary treatment beyond corticosteroids such as targeted anti- inflammatory drugs (eg, aspirin, thalidomide and tumour necrosis factor- alpha antibodies), need further evalua-tion.12 29

Serious adverse events in children during TB treatment are rare although severe hepatotoxic events were occasionally reported.14 30 In a review by Donald,14 abnormal LFTs and jaun-dice were recorded, respectively, in 53% and in 10% of children during TBM therapy. In Indonesian settings, DILI frequently occurred in children during the first 2 months of TB therapy,31 32 with most of them being treated for TBM.31 The reason why patients with TBM are more likely to develop DILI is unclear but could be related to the severity of the underlying disease.33 Of note, this hepatotoxic event could have been the result of hepatic adaptation.19 The temporary use of streptomycin in this study could not be regarded as an effective treatment.10 34 Better management of DILI in children (including criteria to continue treatment in severe conditions and drug reintroduction regi-mens) is needed.

Data on the relationship between DILI and anti- TB drug exposures in children are lacking.14 In Chinese and Indian adults with PTB/extrapulmonary TB, higher isoniazid and rifampicin exposures were associated with an increased risk of DILI.35 36 High- dose rifampicin was not associated with an increase in DILI when administered to Tanzanian and South- African adults with PTB.37 In Indonesian adult patients with

Table 2 Summary of pharmacokinetic (PK) parameters of isoniazid, rifampicin and pyrazinamide among Indonesian children treated for TBM

PK parametersFirst PK assessment (n=20)

Second PK assessment (n=12) P value*

Isoniazid

AUC0–24 (h∙mg/L) 18.5 (5.1–47.4) 14.5 (5.9–44.2) 0.888

Cmax (mg/L) 4.6 (1.0–10.0) 4.7 (2.5–13.6) 0.366

CCSF0–2 (mg/L)† 1.4 (0.5–6.1) 1.6 (1.2–2.5) n/a

CCSF3–5 (mg/L)† 1.6 (0.3–5.0) 1.7 (0.6–5.0) n/a

CCSF6–8 (mg/L)† 1.3 (1.2–4.3) 2.3 (1.9–2.8) n/a

Rifampicin

AUC0–24 (h∙mg/L) 66.9 (21.7–118.6) 71.8 (36.1–116.5) 0.442

Cmax (mg/L) 9.4 (2.9–23.7) 10.4 (5.7–23.3) 0.499

CCSF0–2 (mg/L)† 0.2 (0.1–0.4) 0.1 (0.1–0.1) n/a

CCSF3–5 (mg/L)† 0.3 (0.1–0.8) 0.1 (0.1–0.3) n/a

CCSF6–8 (mg/L)† 0.4 (0.1–1.4) 0.2 (0.1–0.7) n/a

Pyrazinamide

AUC0–24 (h∙mg/L) 315.5 (100.6–599.0) 328.4 (143.3–1477.7) 0.482

Cmax (mg/L) 37.7 (15.9–61.7) 40.5 (22.7–88.4) 0.350

CCSF0–2 (mg/L)† 24.4 (11.1–54.9) 25.6 (21.3–37.1) n/a

CCSF3–5 (mg/L)† 30.0 (19.2–43.3) 24.7 (15.9–38.1) n/a

CCSF6–8 (mg/L)† 19.6 (7.2–37.7) 39.4 (23.1–70.8) n/a

Data are presented as geometric mean (range). The first PK assessment was performed on day 2 of treatment and the second PK assessment was performed on day 10 of treatment.*Paired- sample t- test on log- transformed data of 12 patients for whom PK data were available both at the first and second PK assessments.†At the first PK assessment, 6, 7 and 7 CSF samples for each drug were available at 0–2 hours, 3–5 hours and 6–8 hours, respectively; and at the second PK assessment, 4, 4 and 3 CSF samples for each drug were available at 0–2 hours, 3–5 hours and 6–8 hours, respectively.AUC0–24, area under the plasma concentration–time curve from 0 to 24 hours postdose; CCSF0–8, drug concentration in cerebrospinal fluid during 0–8 hours postdose; Cmax, peak plasma concentration; n/a, non- applicable; TBM, tuberculous meningitis.

Table 3 Multivariate linear regression analysis of factors associated with AUC0–24, Cmax and CSF concentrations of isoniazid, rifampicin and pyrazinamide in Indonesian children treated for TBM

AUC0–24, hour∙mg/L(B (95% CI))

Cmax, mg/L(B (95% CI))

CCSF0–8, mg/L(B (95% CI))

Isoniazid

Age, years n/a −0.020 (−0.043 to 0.003)# n/a

Random blood glucose, mg/dL −0.002 (−0.006 to 0.003) −0.004 (−0.009 to 0.001) −0.007 (−0.015 to 0.001)#

Drug dose, mg/kg 0.016 (−0.048 to 0.080) n/a 0.046 (−0.058 to 0.151)

Drug administration via NGT, no/yes 0.439 (0.143 to 0.735)** 0.130 (−0.160 to 0.420) 0.289 (−0.197 to 0.775)

Rifampicin

Age, years −0.009 (−0.028 to 0.010) −0.008 (−0.029 to 0.012) −0.021 (−0.052 to 0.009)

Random blood glucose, mg/dL −0.003 (−0.007 to 0.001) −0.005 (−0.009 to −0.0003)* n/a

Drug dose, mg/kg 0.014 (−0.021 to 0.048) n/a 0.030 (−0.030 to 0.091)

Drug administration via NGT, no/yes n/a 0.067 (−0.194 to 0.328) 0.019 (−0.365 to 0.403)

Pyrazinamide

Random blood glucose, mg/dL −0.006 (−0.010 to −0.003)** −0.003 (−0.005 to −0.001)** −0.006 (−0.010 to −0.003)**

Drug dose, mg/kg 0.010 (−0.006 to 0.027) 0.010 (0.001 to 0.020)* 0.010 (−0.006 to 0.027)

Drug administration via NGT, no/yes −0.068 (−0.293 to 0.156) 0.036 (−0.095 to 0.167) −0.068 (−0.293 to 0.156)

Data are presented as regression coefficients (B) and 95% CIs. #p<0.1, *p<0.05, **p<0.01.The total explained variance (R2) for isoniazid AUC0–24: 0.57, isoniazid Cmax: 0.46, isoniazid CCSF0–8: 0.45; rifampicin AUC0–24: 0.31, rifampicin Cmax: 0.38, rifampicin CCSF0–8: 0.33, pyrazinamide AUC0–24: 0.53, pyrazinamide Cmax: 0.63 and pyrazinamide CCSF0–8: 0.53.AUC0–24, area under the plasma concentration–time curve from 0 to 24 hours postdose at the first PK assessment; CCSF0–8, CSF concentrations during 0–8 hours postdose at the first PK assessment; CI, confidence interval; Cmax, peak plasma concentration at the first PK assessment; n/a, non- applicable; NGT, nasogastric tube; TBM, tuberculous meningitis.


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TBM, hepatotoxicity was not related to rifampicin expo-sure20 27 and was equally distributed between rifampicin standard- dose and high- dose groups.18 20 27 It should be acknowledged that neither the current study nor the previous studies in Indonesian adults18 20 27 were powered to test for an association between drug levels and DILI. Our findings on DILI in children with TBM warrant further investigation as DILI has clinical implications in increasing patient morbidity/mortality.38 The risk of DILI with increased drug dosages requires consideration, but it should be balanced against the need to ensure optimal treatment of a life- threatening illness like TBM.29 39 Combining therapeutic drug monitoring as a decisive tool for TB treatment,40 and regular monitoring of LFTs,19 might benefit to ensure drug efficacy without causing toxicity.

Our study has some limitations. Conducting intensive PK studies in children is challenging. Ideally, multiple CSF samples are required to assess CSF- to- plasma ratio for total drug exposure.41 Although we were able to collect two PK curves with a modest number of plasma samples, only one

CSF sample per patient could be collected. As a result, AUC0–

24 and Cmax in CSF could not be determined. None of our patients had definite TBM because mycobacterial confirma-tion is known to be a significant challenge in children, due to the paucibacillary nature of the disease and low CSF volumes available for diagnostic analysis.42 Relatively few young chil-dren who may be considered most at risk for being under-dosed were included in this study. Our results pointed out, however, no difference in drug exposure between younger and older children. Of note, our population was not repre-sentative of the total paediatric TBM patients diagnosed over the study period. Due to the small sample size, our findings on predictors of exposure to anti- TB drugs and the relation-ship of drug exposures with DILI and 6- month mortality should be interpreted with caution. It could be of value to collect data on drug exposure and pathogen susceptibility in a large cohort to overcome the limitations of small- scale PK studies.43

In conclusion, suboptimal plasma and CSF rifampicin concen-trations were observed in all patients, and there is an urgent need

Figure 2 Pharmacokinetic profiles of isoniazid (INH), rifampicin (RIF) and pyrazinamide (PZA) on day 10 of tuberculous meningitis treatment in children and adolescents who developed antituberculosis drug- induced liver- injury (DILI, n=3*) and those without DILI (n=9). (A) INH plasma concentration vs time curve; (B) RIF plasma concentration vs time curve; (C) PZA plasma concentration vs time curve; (D) INH area under the concentration–time curve during the dosing interval (AUC0–24); (E) RIF AUC0–24; (F) PZA AUC0–24. Box plots represent medians with IQRs; lower and upper whiskers represent first and fourth quartiles, respectively. *Of four patients with DILI, one who developed DILI on day 7 of treatment did not have INH, RIF and PZA concentrations measured on day 10 because the drugs had been temporarily stopped due to DILI.


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to increase the rifampicin dose in children and adolescents with TBM. Intensified regimens containing anti- TB drugs with better CSF penetration, along with other ancillary treatment for paedi-atric TBM, warrant further evaluation. The association between higher isoniazid, rifampicin and pyrazinamide concentrations and the development of DILI needs confirmatory studies.

Author affiliations1Division of Pharmacology and Therapy, Department of Biomedical Sciences, Faculty of Medicine, Universitas Padjadjaran, Bandung, Indonesia2Unit of PharmacoTherapy, -Epidemiology and -Economics, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands3Department of Clinical Pathology, Faculty of Medicine, Universitas Padjadjaran, Hasan Sadikin Hospital, Bandung, Indonesia4Department of Neurology, Faculty of Medicine, Universitas Padjadjaran, Hasan Sadikin Hospital, Bandung, Indonesia5Department of Pharmacy, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands6Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands7School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia8Westmead Hospital, Sydney, New South Wales, Australia9Division of Pediatric Respirology, Department of Child Health, Faculty of Medicine, Universitas Padjadjaran, Hasan Sadikin Hospital, Bandung, Indonesia

Acknowledgements We would like to thank the director of Hasan Sadikin Hospital for accommodating the research. We would also like to thank all the patients for their participation in the study, as well as Yuanita Gunawan, Sheila Sumargo, Nadytia Kusumadjayanti and Aulia Rahman for monitoring the patients and data recording.

Contributors RR was the principal investigator. RR, VY, IP, ARG, and HMN contributed to conception and design of the study. VY performed PK sampling and bioanalyses of anti- TB drugs under RR supervision. FG performed data analyses and created tables and figures. RR, FG, VY, IP, ARG, REA, BW, J- WCA and HMN interpreted the results. FG drafted the manuscript under the supervision of RR, REA, BW and J- WCA. All authors critically revised the manuscript for important intellectual content and approved the final version of the manuscript.

Funding This work was supported by the Universitas Padjadjaran through the Academic Leadership Grant and by the University of Groningen through the Indonesia Endowment Fund for Education Scholarship (LPDP; 201711220412046).

Competing interests None declared.

Patient consent for publication Not required.

Ethics approval Research approval was granted by the Independent Ethics Committee, Faculty of Medicine, Universitas Padjadjaran (No: LB.04.01/A05/EC/029/II/2018).

Provenance and peer review Not commissioned; externally peer reviewed.

Data availability statement The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer- reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

Open access This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https:// creativecommons. org/ licenses/ by/ 4. 0/.

ORCID iDFajri Gafar http:// orcid. org/ 0000- 0002- 0084- 9018

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1

Supplementary material:

Pharmacokinetics and safety/tolerability of isoniazid, rifampicin and pyrazinamide in

children and adolescents treated for tuberculous meningitis

Rovina Ruslami,1,¶ Fajri Gafar,2,¶,* Vycke Yunivita,1 Ida Parwati,3 Ahmad R. Ganiem,4 Rob E.

Aarnoutse,5 Bob Wilffert,2,6 Jan-Willem C. Alffenaar,7,8 Heda M. Nataprawira9

[1] Universitas Padjadjaran, Faculty of Medicine, Department of Biomedical Sciences, Division

of Pharmacology and Therapy, Bandung, Indonesia; [2] University of Groningen, Groningen

Research Institute of Pharmacy, Unit of PharmacoTherapy, -Epidemiology, and -Economics,

Groningen, the Netherlands; [3] Universitas Padjadjaran, Hasan Sadikin Hospital, Faculty of

Medicine, Department of Clinical Pathology, Bandung, Indonesia; [4] Universitas Padjadjaran,

Hasan Sadikin Hospital, Faculty of Medicine, Department of Neurology, Bandung, Indonesia;

[5] Radboud University Medical Center, Radboud Institute for Health Sciences, Department of

Pharmacy, Nijmegen, The Netherlands; [6] University of Groningen, University Medical Center

Groningen, Department of Clinical Pharmacy and Pharmacology, Groningen, the Netherlands;

[7] University of Sydney, Faculty of Medicine and Health, School of Pharmacy, Sydney,

Australia; [8] Westmead Hospital, Sydney, Australia; and [9] Universitas Padjadjaran, Hasan

Sadikin Hospital, Faculty of Medicine, Department of Child Health, Division of Pediatric

Respirology, Bandung, Indonesia.

¶These first authors contributed equally to this manuscript

*Corresponding author:

Fajri Gafar; University of Groningen, Groningen Research Institute of Pharmacy, Unit of

PharmacoTherapy, -Epidemiology and -Economics, Antonius Deusinglaan 1 (room:

3214.0450), 9713 AV Groningen, The Netherlands, E-mail: [email protected]

BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any relianceSupplemental material placed on this supplemental material which has been supplied by the author(s) Arch Dis Child

doi: 10.1136/archdischild-2020-321426–8.:10 2021;Arch Dis Child, et al. Ruslami R

2

Appendix-1. PK assessments

On both sampling days, blood and CSF samples were collected for each patient in EDTA-

coated tubes, placed immediately on ice, centrifuged at 3000 rpm for 15 min, and stored at -

80 °C within 30 min after sample collection. Bioanalysis was performed at the Pharmacokinetic

Laboratory of the Faculty of Medicine of Universitas Padjadjaran, using an ultra-performance

liquid chromatography method [1]. The accuracy for plasma and CSF assays ranged,

respectively, from 101.7-109.0% and 97.1-103.0% for isoniazid, 95.1-102.4% and 94.5-

100.7% for rifampicin, and 99.1-102.1% and 85.8-95.5% for pyrazinamide, depending on the

concentration level. Intraday and interday coefficients of variation were <7.9% and <8.1% over

the 0.15-15 mg/L concentration range for isoniazid in plasma and CSF, <4.2% and <3.4% over

the concentration ranges of 0.125-30 mg/L and 0.25-30 mg/L for rifampicin in plasma and

CSF, and <3.9% and <6.6% over the 0.20-60.06 mg/L concentration range for pyrazinamide

in plasma and CSF, respectively.

PK parameters were assessed noncompartmentally using the R package “PKNCA”

ver.0.9.4 in R for Windows. Drug concentrations below the lower limit of quantification (LLOQ)

were set to half of the LLOQ. Main PK measures were area under the plasma concentration-

time curve during the dosing interval (AUC0-24), peak plasma concentration (Cmax) and CSF

concentration (CCSF0-8). Cmax and the corresponding time to Cmax (Tmax), were derived directly

from the concentration-time curves. Plasma concentration at 24 h post-dose was calculated

with the formula: C24=Clast×e−β×(24−Tlast), in which Clast is the last measurable concentration at

Tlast, and β is the first order elimination rate constant. β was obtained by least-squares linear

regression analysis on log concentration versus time, with the absolute slope of the regression

line being β/2.303. The terminal log-linear phase was determined by the last three data points;

if the last three points were not available, only the last two points were used. The elimination

half-life (t1/2) was obtained by the equation: 0.693/β. AUC0-24 was calculated based on the

linear-up/log-down trapezoidal rule. Apparent clearance (CL/F) was obtained by dividing the

dose by AUC0-24, and apparent volume distribution (Vd/F) was obtained by dividing CL/F by β.



3

Appendix-2. Statistical analysis

Predictors of drug exposures were evaluated using univariate and multivariate linear

regression analyses. Variables in the univariate analysis showing a trend towards association

(p<0.25) with each of the above dependent PK variables were eligible for inclusion in a

multivariate analysis. Due to the small sample size of patients, we only allowed a maximum of

three variables to be included in the multivariate models. The models having the highest total

explained variance (R2) and preferably including the highest number of patients were selected

as the final models.



5

Appendix-4. Additional pharmacokinetic (PK) parameters of isoniazid, rifampicin and

pyrazinamide among Indonesian children treated for TBM.

PK parameters 1st PK assessment (n=20) 2nd PK assessment (n=12) p-value

Isoniazid

Tmax (h)a 1.0 (1.0-1.9) 1.0 (1.0-1.0) 0.107c

CL/F (L/h) 9.8 (1.1-59.0) 14.0 (4.6-42.2) 0.888b

Vd/F (L) 11.9 (2.1-63.7) 13.8 (4.8-35.8) 0.815b

t1/2 (h) 0.8 (0.3-2.0) 0.7 (0.3-1.0) 0.945b

Rifampicin

Tmax (h)a 4.0 (2.0-4.0) 2.0 (1.0-3.5) 0.015c

CL/F (L/h) 4.1 (0.9-20.7) 4.2 (2.4-11.2) 0.442b

Vd/F (L) 11.2 (1.7-52.9) 12.2 (2.6-56.0) 0.973b

t1/2 (h) 1.9 (1.0-10.0) 2.0 (0.7-6.2) 0.656b

Pyrazinamide

Tmax (h)a 1.0 (1.0-2.0) 1.0 (1.0-1.0) 0.196c

CL/F (L/h) 1.7 (0.2-8.9) 1.8 (0.4-5.2) 0.482b

Vd/F (L) 8.6 (2.5-29.2) 9.2 (3.6-18.8) 0.614b

t1/2 (h) 3.5 (1.8-7.6) 3.4 (1.5-16.2) 0.592b

Data are presented as geometric mean (range), unless otherwise stated a:median

(interquartile range). The first PK assessment was performed on day 2 of treatment, and the

second PK assessment was performed on day 10 of treatment. Tmax: time to peak plasma

concentration; CL/F: apparent total clearance; Vd/F: apparent volume distribution; t1/2:

elimination half-life; TBM: tuberculous meningitis. b:Paired-sample t-test on log-transformed

data of 12 patients for whom PK data were available both at the first and second PK

assessments c:Wilcoxon signed-rank test between the first and second PK assessments.



6

Appendix-5. Correlations between AUC0-24, Cmax and CCSF0-8 at the first and second PK

assessments of Indonesian children treated for TBM.

Isoniazid Rifampicin Pyrazinamide

r p-value r p-value r p-value

1st PK assessment (day 2)

AUC0-24 vs. Cmax 0.83 <0.001 0.80 <0.001 0.89 <0.001

AUC0-24 vs. CCSF0-8 0.69 0.001 0.49 0.028 0.77 <0.001

Cmax vs. CCSF0-8 0.59 0.007 0.60 0.005 0.72 <0.001

2nd PK assessment (day 10)

AUC0-24 vs. Cmax 0.96 <0.001 0.69 0.014 0.91 <0.001

AUC0-24 vs. CCSF0-8 0.88 <0.001 0.50 0.121 0.92 <0.001

Cmax vs. CCSF0-8 0.80 0.003 0.17 0.611 0.91 <0.001

Data are presented as Pearson correlation coefficient (r). AUC0-24: area under the plasma

concentration-time curve from 0-24 h post-dose; Cmax: peak plasma concentration; CCSF0-8:

cerebrospinal fluid concentration during 0-8 h post dose; TBM: tuberculous meningitis.



7

Appendix-6. Univariate linear regression analysis of factors associated with AUC0-24, Cmax and CCSF0-8

of isoniazid, rifampicin and pyrazinamide in Indonesian children treated for TBM.

AUC0-24, h∙mg/L

(B [95% CI])

Cmax, mg/L

(B [95% CI])

CCSF0-8, mg/L

(B [95% CI])

Isoniazid

Age, years -0.02 (-0.05; -0.002)* -0.02 (-0.05; -0.003)* -0.02 (-0.06; 0.01)

Sex, male/female 0.05 (-0.24; 0.35) 0.01 (-0.27; 0.28) -0.04 (-0.45; 0.38) aMalnourished, no/yes 0.29 (0.001; 0.57)* 0.10 (-0.20; 0.39) 0.41 (0.01; 0.82)*

Albumin, g/dL -0.13 (-0.35; 0.10) -0.16 (-0.38; 0.06) -0.003 (-0.32; 0.32)

Random blood glucose, mg/dL -0.004 (-0.01; 0.002) -0.006 (-0.01; -0.0002)* -0.01 (-0.02; -0.001)*

Creatinine clearance, mg/min 0.00 (-0.005l 0.006) -0.001 (-0.01; 0.004) 0.00 (-0.01; 0.01)

TBM grade, 1/2/3 0.03 (-0.20; 0.26) -0.003 (-0.22; 0.21) -0.04 (-0.36; 0.29)

GCS score -0.02 (-0.08; 0.05) -0.001 (-0.06; 0.06) -0.02 (-0.11; 0.07)

Drug dose, mg/kg 0.07 (0.001; 0.13)* 0.04 (-0.02; 0.11) 0.09 (-0.001; -0.19)#

Drug administration via NGT, no/yes 0.39 (0.14; 0.65)** 0.23 (-0.04; 0.51)# 0.44 (0.05; 0.84)*

Rifampicin

Age, years -0.01 (-0.03; 0.003) -0.02 (-0.03; 0.003) -0.03 (-0.05; -0.005)*

Sex, male/female -0.06 (-0.25; 0.13) -0.13 (-0.35; 0.10) -0.06 (-0.39; 0.26) aMalnourished, no/yes 0.11 (-0.09; 0.31) 0.08 (-0.17; 0.33) -0.13 (-0.48; 0.21)

Albumin, g/dL -0.06 (-0.19; 0.07) -0.09 (-0.25; 0.07) -0.09 (-0.35; 0.16)

Random blood glucose, mg/dL -0.003 (-0.01; 0.0005)# -0.006 (-0.01; -0.001)* -0.003 (-0.01; 0.004)

Creatinine clearance, mg/min -0.001 (-0.004; 0.003) -0.003 (-0.01; 0.001) -0.001 (-0.01; 0.005)

TBM grade, 1/2/3 -0.03 (-0.18; 0.12) -0.02 (-0.20; 0.16) 0.05 (-0.20; 0.31)

GCS score 0.01 (-0.04; 0.05) 0.004 (-0.05; 0.06) -0.04 (-0.11; 0.03)

Drug dose, mg/kg 0.02 (-0.01; 0.05) 0.02 (-0.02; 0.05) 0.05 (0.004; 0.10)*

Drug administration via NGT, no/yes 0.10 (-0.10; 0.30) 0.18 (-0.06; 0.41) 0.25 (-0.08; 0.58)

Pyrazinamide

Age, years -0.01 (-0.03; 0.001)# -0.01 (-0.02; 0.00)# -0.01 (-0.02; 0.01)

Sex, male/female 0.08 (-0.11; 0.28) 0.04 (-0.09; 0.18) 0.05 (-0.15; 0.26) aMalnourished, no/yes 0.04 (-0.17; 0.25) 0.05 (-0.10; 0.19) 0.01 (-0.22; 0.24)

Albumin, g/dL -0.12 (-0.24; 0.003)# -0.07 (-0.16; 0.02) -0.05 (-0.21; 0.09)

Random blood glucose, mg/dL -0.005 (-0.01; -0.001)* -0.004 (-0.01; -0.001)** -0.006 (-0.01; -0.003)**

Creatinine clearance, mg/min 0.00 (-0.004; 0.003) -0.001 (-0.003; 0.002) 0.00 (-0.004; 0.004)

TBM grade, 1/2/3 -0.03 (-0.19; 0.12) -0.05 (-0.15; 0.06) -0.06 (-0.23; 0.10)

GCS score -0.01 (-0.05; 0.03) 0.01 (-0.02; 0.04) -0.003 (-0.05; 0.04)

Drug dose, mg/kg 0.02 (0.002; 0.03)* 0.01 (0.005; 0.02)** 0.01 (-0.005; 0.03)

Drug administration via NGT, no/yes 0.20 (0.02; 0.39)* 0.15 (0.02; 0.28)* 0.10 (-0.12; 0.32)

Data are presented as regression coefficients (B) and 95% confidence intervals (CI); #p<0.1, *p<0.05,

**p<0.01. AUC0-24: area under the plasma concentration-time curve from 0-24 h post-dose at the first

PK assessment (day 2 of treatment); Cmax: peak plasma concentration at the first PK assessment; CCSF0-

8: CSF concentrations during 0-8 h post-dose at the first PK assessment; GCS: Glasgow comma scale;

NGT: nasogastric tube; TBM: tuberculous meningitis. a: Malnutrition was defined as children aged <5

years with baseline weigh-for-age or height-for-age Z-scores <-2 standard deviations (SD), or children

aged ≥5 years with baseline height-for-age or BMI-for-age Z-scores <-2 SD.



8

Appendix-7. Drug doses, AUC0-24 and Cmax of isoniazid, rifampicin and pyrazinamide in

patients who developed DILI and those without DILI during TBM treatment.

DILI Non-DILI p-value*

1st PK assessment (day 2), n 4 16

Isoniazid

Dose (mg/kg) 10.6 (8.6-12.3) 8.8 (7.5-10.3) 0.185

AUC0-24 (h∙mg/L) 27.1 (19.9-34.4) 16.8 (5.1-47.4) 0.299

Cmax (mg/L) 6.4 (5.1-9.7) 4.3 (1.0-10.0) 0.450

Rifampicin

Dose (mg/kg) 15.8 (12.9-18.5) 13.2 (11.2-15.4) 0.185

AUC0-24 (h∙mg/L) 79.9 (55.9-114.8) 64.0 (21.7-118.6) 0.777

Cmax (mg/L) 10.0 (7.2-16.5) 9.3 (2.9-23.7) 0.850

Pyrazinamide

Dose 31.7 (25.8-36.9) 26.5 (22.5-30.9) 0.185

AUC0-24 (h∙mg/L) 283.0 (198.7-575.4) 324.2 (100.6-599.0) 0.345

Cmax (mg/L) 37.6 (26.3-54.2) 37.7 (15.9-61.7) 0.850

2nd PK assessment (day 10), n 3¶ 9

Isoniazid

Dose (mg/kg) 11.8 (9.4-12.5)§ 8.6 (7.1-9.7) 0.064

AUC0-24 (h∙mg/L) 37.2 (26.6-44.2) 10.6 (5.9-19.9) 0.013

Cmax (mg/L) 10.6 (8.4-13.6) 3.6 (2.5-5.7) 0.013

Rifampicin

Dose (mg/kg) 17.6 (14.1-18.7)§ 12.9 (10.7-14.6) 0.064

AUC0-24 (h∙mg/L) 106.2 (95.4-116.5) 63.0 (36.1-108.0) 0.033

Cmax (mg/L) 13.2 (8.5-23.3) 9.6 (5.7-14.1) 0.405

Pyrazinamide

Dose (mg/kg) 35.3 (28.1-37.5)§ 25.9 (21.4-29.2) 0.064

AUC0-24 (h∙mg/L) 687.5 (423.6-1477.7) 256.7 (143.3-353.9) 0.013

Cmax (mg/L) 62.8 (47.0-88.4) 34.9 (22.7-43.5) 0.013

Drug doses are presented as median (interquartile range), unless otherwise stated §:median

(range). AUC0-24 and Cmax values are presented as geometric mean (range). AUC0-24: area

under the plasma concentration-time curve from 0-24 h post-dose; Cmax: peak plasma

concentration; DILI: antituberculosis drug-induced liver injury; TBM: tuberculous meningitis. ¶:

One patient who developed DILI on day 7 of treatment had no isoniazid, rifampicin and

pyrazinamide concentrations measured at the second PK assessment as the drugs had been

temporarily stopped due to DILI. *: Mann-Whitney U test between patients who developed DILI

and those without DILI.



9

References:

[1] Yunivita V, Dian S, Ganiem AR, Hayati E, Hanggono Achmad T, Purnama Dewi A, et

al. Pharmacokinetics and safety/tolerability of higher oral and intravenous doses of

rifampicin in adult tuberculous meningitis patients. Int J Antimicrob Agents

2016;48:415–21.



pharmacokinetics and safety/tolerability of isoniazid

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