Pharmacokinetics of isoniazid, rifampicin, pyrazinamide and ethambutol in HIV-infected Indian children

An Overview of Various Rifampicin Analogs against Mycobacterium tuberculosis and their Drug Interactions

The success of the TB control program is hampered by the major issue of drug-resistant tuberculosis (DR-TB). The situation has undoubtedly been made more difficult by the widespread and multidrug-resistant (XDR) strains of TB. The modification of existing anti-TB medications to produce derivatives that can function on resistant TB bacilli is one of the potential techniques to overcome drug resistance affordably and straightforwardly. In comparison to novel pharmaceuticals for drug research and progress, these may have a better half-life and greater bioavailability, be more efficient, and serve as inexpensive alternatives. Mycobacterium tuberculosis, which is drugsusceptible or drug-resistant, is effectively treated by several already prescribed medications and their derivatives. Due to this, the current review attempts to give a brief overview of the rifampicin derivatives that can overcome the parent drug's resistance and could, hence, act as useful substitutes. It has been found that one-third of the global population is affected by M. tuberculosis. The most common cause of infection-related death can range from latent TB to TB illness. Antibiotics in the rifamycin class, including rifampicin or rifampin (RIF), rifapentine (RPT), and others, have a special sterilizing effect on M. tuberculosis. We examine research focused on evaluating the safety, effectiveness, pharmacokinetics, pharmacodynamics, risk of medication interactions, and other characteristics of RIF analogs. Drug interactions are especially difficult with RIF because it must be taken every day for four months to treat latent TB infection. RIF continues to be the gold standard of treatment for drug-sensitive TB illness. RIF's safety profile is well known, and the two medicines' adverse reactions have varying degrees of frequency. The authorized once-weekly RPT regimen is insufficient, but greater dosages of either medication may reduce the amount of time needed to treat TB effectively.

Evaluating pediatric tuberculosis dosing guidelines: A model-based individual data pooled analysis

BACKGROUND

The current World Health Organization (WHO) pediatric tuberculosis dosing guidelines lead to suboptimal drug exposures. Identifying factors altering the exposure of these drugs in children is essential for dose optimization. Pediatric pharmacokinetic studies are usually small, leading to high variability and uncertainty in pharmacokinetic results between studies. We pooled data from large pharmacokinetic studies to identify key covariates influencing drug exposure to optimize tuberculosis dosing in children.

METHODS AND FINDINGS

We used nonlinear mixed-effects modeling to characterize the pharmacokinetics of rifampicin, isoniazid, and pyrazinamide, and investigated the association of human immunodeficiency virus (HIV), antiretroviral therapy (ART), drug formulation, age, and body size with their pharmacokinetics. Data from 387 children from South Africa, Zambia, Malawi, and India were available for analysis; 47% were female and 39% living with HIV (95% on ART). Median (range) age was 2.2 (0.2 to 15.0) years and weight 10.9 (3.2 to 59.3) kg. Body size (allometry) was used to scale clearance and volume of distribution of all 3 drugs. Age affected the bioavailability of rifampicin and isoniazid; at birth, children had 48.9% (95% confidence interval (CI) [36.0%, 61.8%]; p < 0.001) and 64.5% (95% CI [52.1%, 78.9%]; p < 0.001) of adult rifampicin and isoniazid bioavailability, respectively, and reached full adult bioavailability after 2 years of age for both drugs. Age also affected the clearance of all drugs (maturation), children reached 50% adult drug clearing capacity at around 3 months after birth and neared full maturation around 3 years of age. While HIV per se did not affect the pharmacokinetics of first-line tuberculosis drugs, rifampicin clearance was 22% lower (95% CI [13%, 28%]; p < 0.001) and pyrazinamide clearance was 49% higher (95% CI [39%, 57%]; p < 0.001) in children on lopinavir/ritonavir; isoniazid bioavailability was reduced by 39% (95% CI [32%, 45%]; p < 0.001) when simultaneously coadministered with lopinavir/ritonavir and was 37% lower (95% CI [22%, 52%]; p < 0.001) in children on efavirenz. Simulations of 2010 WHO-recommended pediatric tuberculosis doses revealed that, compared to adult values, rifampicin exposures are lower in most children, except those younger than 3 months, who experience relatively higher exposure for all drugs, due to immature clearance. Increasing the rifampicin doses in children older than 3 months by 75 mg for children weighing <25 kg and 150 mg for children weighing >25 kg could improve rifampicin exposures. Our analysis was limited by the differences in availability of covariates among the pooled studies.

CONCLUSIONS

Children older than 3 months have lower rifampicin exposures than adults and increasing their dose by 75 or 150 mg could improve therapy. Altered exposures in children with HIV is most likely caused by concomitant ART and not HIV per se. The importance of the drug-drug interactions with lopinavir/ritonavir and efavirenz should be evaluated further and considered in future dosing guidance.

TRIAL REGISTRATION

ClinicalTrials.gov registration numbers; NCT02348177, NCT01637558, ISRCTN63579542.

Therapeutic drug monitoring in India: A strength, weakness, opportunity and threats analysis

Over the last three to four decades, Therapeutic Drug Monitoring (TDM) has shaped itself as therapeutic drug management, an integral component of precision medicine. The practice of TDM is not extensive in India, despite being one of the fastest-growing economies in the world. It is currently limited to a few academic medical centres and teaching hospitals. Apart from the immunosuppressive drugs, several other therapeutic areas, such as anticancer, antifungal, antibiotic and antitubercular, have demonstrated great potential to improve patient outcomes in Indian settings. Factors such as the higher prevalence of nutritional deficiencies, tropical diseases, widespread use of alternative medicines, unalike pharmacogenomics and sparse population-specific data available on therapeutic ranges of several drugs make the population of this subcontinent unique regarding the relevance of TDM. Despite the impact of TDM in clinical science and its widespread application, TDM has failed to receive the attention it deserves in India. This review intends to bring out a strength, weakness, opportunity and threats (SWOT) analysis for TDM in India so that appropriate steps for fostering the growth of TDM could be envisioned. The need of the hour is the creation of a cooperative group including all the stakeholders, such as TDM professionals, clinicians and the government and devising a National Action Plan to strengthen TDM. Nodal TDM centres should be established, and pilot programmes should be rolled out to identify the thrust areas for TDM in the country, capacity building and creating awareness to integrate TDM into mainstream clinical medicine.

Global estimates and determinants of antituberculosis drug pharmacokinetics in children and adolescents: a systematic review and individual patient data meta-analysis

BACKGROUND

Suboptimal exposure to antituberculosis (anti-TB) drugs has been associated with unfavourable treatment outcomes. We aimed to investigate estimates and determinants of first-line anti-TB drug pharmacokinetics in children and adolescents at a global level.

METHODS

We systematically searched MEDLINE, Embase and Web of Science (1990-2021) for pharmacokinetic studies of first-line anti-TB drugs in children and adolescents. Individual patient data were obtained from authors of eligible studies. Summary estimates of total/extrapolated area under the plasma concentration-time curve from 0 to 24 h post-dose (AUC0-24) and peak plasma concentration (C max) were assessed with random-effects models, normalised with current World Health Organization-recommended paediatric doses. Determinants of AUC0-24 and C max were assessed with linear mixed-effects models.

RESULTS

Of 55 eligible studies, individual patient data were available for 39 (71%), including 1628 participants from 12 countries. Geometric means of steady-state AUC0-24 were summarised for isoniazid (18.7 (95% CI 15.5-22.6) h·mg·L-1), rifampicin (34.4 (95% CI 29.4-40.3) h·mg·L-1), pyrazinamide (375.0 (95% CI 339.9-413.7) h·mg·L-1) and ethambutol (8.0 (95% CI 6.4-10.0) h·mg·L-1). Our multivariate models indicated that younger age (especially <2 years) and HIV-positive status were associated with lower AUC0-24 for all first-line anti-TB drugs, while severe malnutrition was associated with lower AUC0-24 for isoniazid and pyrazinamide. N-acetyltransferase 2 rapid acetylators had lower isoniazid AUC0-24 and slow acetylators had higher isoniazid AUC0-24 than intermediate acetylators. Determinants of C max were generally similar to those for AUC0-24.

CONCLUSIONS

This study provides the most comprehensive estimates of plasma exposures to first-line anti-TB drugs in children and adolescents. Key determinants of drug exposures were identified. These may be relevant for population-specific dose adjustment or individualised therapeutic drug monitoring.

Adequacy of the 10 mg/kg Daily Dose of Antituberculosis Drug Isoniazid in Infants under 6 Months of Age

In 2010, the WHO recommended an increase in the daily doses of first-line anti-tuberculosis medicines in children. We aim to characterize the pharmacokinetics of the once-daily isoniazid (INH) dose at 10 mg/kg of body weight in infants <6 months of age. We performed a multicenter pharmacokinetic study in Spain. The N-acetyltransferase 2 gene was analyzed to determine the acetylation status. Samples were analyzed using a validated UPLC-UV assay. A non-compartmental pharmacokinetic analysis was performed. Twenty-three pharmacokinetic profiles were performed in 20 infants (8 females) at a median (IQR) age of 19.0 (12.6-23.3) weeks. The acetylator statuses were homozygous fast (n = 1), heterozygous intermediate (n = 12), and homozygous slow (n = 7). INH median (IQR) C_max and AUC_0-24h values were 4.8 (3.7-6.7) mg/L and 23.5 (13.4-36.7) h*mg/L and the adult targets (>3 mg/L and 11.6-26.3 h*mg/L) were not reached in three and five cases, respectively. The age at assessment or acetylator status had no impact on C_max values, but a larger INH AUC_0-24h (p = 0.025) and trends towards a longer half-life (p = 0.055) and slower clearance (p = 0.070) were observed in homozygous slow acetylators. Treatment was well tolerated; mildly elevated alanine aminotransferase levels were observed in three cases. In our series of young infants receiving isoniazid, no major safety concerns were raised, and the target adult levels were reached in most patients.

Effectiveness and pharmacokinetic exposures of first-line drugs used to treat drug-susceptible tuberculosis in children: a systematic review and meta-analysis

BACKGROUND

Optimal doses of first line drugs for drug-susceptible tuberculosis (DS-TB) treatment in children and young adolescents remain uncertain. We aimed to determine if children treated using WHO-recommended or higher doses of first-line drugs achieve successful outcomes and sufficient pharmacokinetic exposures.

METHODS

Titles, abstracts, and full-text articles were screened. We searched Pubmed, EMBASE, CENTRAL, and trial registries from 2010 to 2021. We included studies in children <18 years, being treated for DS-TB with rifampicin, pyrazinamide, isoniazid, and ethambutol. Outcomes were treatment success rates and drug exposures. The protocol for the systematic review was preregistered in PROSPERO, CRD42021274222.

RESULTS

Of 304 studies identified, 46 studies were eligible for full-text review and 12 and 18 articles were included for the efficacy and pharmacokinetic analysis, respectively. Of 1,830 children included in the efficacy analysis, 82% had favourable outcomes (range 25%-95%). At WHO-recommended doses, exposures to rifampicin, pyrazinamide, and ethambutol were lower in children as compared to adults. Children ≤6 years have 35% lower AUC than older children (14.4 (9.9-18.8) vs 22.0 (13.8-30.1) μg.h/mL) and children with HIV (CWHIV) had 35% lower rifampicin AUC than HIV negative children (17.3 (11.4-23.2) vs 26.5 (21.3-31.7) μg.h/mL). Heterogeneity and small sample sizes were major limitations.

CONCLUSION

There is large variability in outcomes with an average 82% favourable outcomes. Drug exposures are lower in children than in adults. Younger children and CWHIV are underexposed to rifampicin. Standardization of pharmacokinetic paediatric studies and individual patient data analysis with safety assessment are needed to inform optimal dosing.

Systematic review with network meta-analysis on the treatments for latent tuberculosis infection in children and adolescents

BACKGROUND

We aimed to synthesize the evidence on the efficacy and safety of different treatment regimens for latent tuberculosis infection (LTBI) in children and adolescents.

METHODS

A systematic review with network meta-analysis was performed (CRD142933). Searches were conducted in Pubmed and Scopus (Nov-2021). Randomized controlled trials comparing treatments for LTBI (patients up to 15 years), and reporting data on the incidence of the disease, death or adverse events were included. Networks using the Bayesian framework were built for each outcome of interest. Results were reported as odds ratio (OR) with 95% credibility intervals (CrI). Rank probabilities were calculated via the surface under the cumulative ranking analysis (SUCRA) (Addis-v.1.16.8). GRADE approach was used to rate evidence's certainty.

RESULTS

Seven trials (n = 8696 patients) were included. Placebo was significantly associated with a higher incidence of tuberculosis compared to all active therapies. Combinations of isoniazid (15-25 mg/kg/week) plus rifapentine (300-900 mg/week), followed by isoniazid plus rifampicin (10 mg/kg/day) were ranked as best approaches with lower probabilities of disease incidence (10% and 19.5%, respectively in SUCRA) and death (20%). Higher doses of isoniazid monotherapy were significantly associated to more deaths (OR 18.28, 95% ICr [1.02, 48.60] of 4-6 mg/kg/day vs. 10 mg/kg/3x per week).

CONCLUSIONS

Combined therapies of isoniazid plus rifapentine or rifampicin for short-term periods should be used as the first-line approach for treating LTBI in children and adolescents. The use of long-term isoniazid as monotherapy and at higher doses should be avoided for this population.

Emerging data on rifampicin pharmacokinetics and approaches to optimal dosing in children with tuberculosis

INTRODUCTION

Despite its longstanding role in tuberculosis (TB) treatment, there continues to be emerging rifampicin research that has important implications for pediatric TB treatment and outstanding questions about its pharmacokinetics and optimal dose in children.

AREAS COVERED

This review aims to summarize and discuss emerging data on the use of rifampicin for: 1) routine treatment of drug-susceptible TB; 2) special subpopulations such as children with malnutrition, HIV, or TB meningitis; 3) treatment shortening. We also highlight the implications of these new data for child-friendly rifampicin formulations and identify future research priorities.

EXPERT OPINION

New data consistently show low rifampicin exposures across all pediatric populations with 10-20 mg/kg dosing. Although clinical outcomes in children are generally good, rifampicin dose optimization is needed, especially given a continued push to shorten treatment durations and for specific high-risk populations of children who have worse outcomes. A pooled analysis of existing data using applied pharmacometrics would answer many of the important questions remaining about rifampicin pharmacokinetics needed to optimize doses, especially in special populations. Targeted clinical studies in children with TB meningitis and treatment shortening with high-dose rifampicin are also priorities.

Updates in Pediatric Tuberculosis in International Settings

Childhood tuberculosis (TB) has been underreported and underrepresented in TB statistics across the globe. Contributing factors include health system barriers, diagnostic barriers, and community barriers leading to an underdetected epidemic of childhood tuberculosis. Despite considerable progress in childhood TB management, there is a concerning gap in policy and practice in high-burden countries leading to missed opportunities for active case detection, early diagnosis and treatment of TB exposure, and infection and disease in children regardless of human immunodeficiency virus status. Bridging this gap requires multisectoral coordination and political commitment along with an eye to research and innovation with potential to scale.

Pharmacokinetics of antiretroviral and tuberculosis drugs in children with HIV/TB co-infection: a systematic review

INTRODUCTION

Management of concomitant use of ART and TB drugs is difficult because of the many drug-drug interactions (DDIs) between the medications. This systematic review provides an overview of the current state of knowledge about the pharmacokinetics (PK) of ART and TB treatment in children with HIV/TB co-infection, and identifies knowledge gaps.

METHODS

We searched Embase and PubMed, and systematically searched abstract books of relevant conferences, following PRISMA guidelines. Studies not reporting PK parameters, investigating medicines that are not available any longer or not including children with HIV/TB co-infection were excluded. All studies were assessed for quality.

RESULTS

In total, 47 studies met the inclusion criteria. No dose adjustments are necessary for efavirenz during concomitant first-line TB treatment use, but intersubject PK variability was high, especially in children <3 years of age. Super-boosted lopinavir/ritonavir (ratio 1:1) resulted in adequate lopinavir trough concentrations during rifampicin co-administration. Double-dosed raltegravir can be given with rifampicin in children >4 weeks old as well as twice-daily dolutegravir (instead of once daily) in children older than 6 years. Exposure to some TB drugs (ethambutol and rifampicin) was reduced in the setting of HIV infection, regardless of ART use. Only limited PK data of second-line TB drugs with ART in children who are HIV infected have been published.

CONCLUSIONS

Whereas integrase inhibitors seem favourable in older children, there are limited options for ART in young children (<3 years) receiving rifampicin-based TB therapy. The PK of TB drugs in HIV-infected children warrants further research.

A Systematic Review and Meta-analysis of Isoniazid Pharmacokinetics in Healthy Volunteers and Patients with Tuberculosis

PURPOSE

This systematic review and meta-analysis assesses the pharmacokinetic (PK) summary estimates of isoniazid (INH) between healthy volunteers and patients with tuberculosis (TB), evaluates whether the current INH dose regimen is appropriate in patients with TB, and evaluates the impact of N-acetyl-transferase-2 (NAT2) status on the PK properties of INH.

METHODS

A systematic approach was conducted to find studies with relevant INH PK data published in the English language up to February 2018. The PK properties of INH were extracted with their respective INH dosages and were dose normalized to allow a fair comparison between healthy volunteers and patients with TB. Meta-analysis was then performed for the C_max and AUC estimates for all INH dosages.

FINDINGS

Ninety studies were included in this systematic review. TB status significantly affected the INH C_max and AUC estimates. In healthy volunteers, the dose-normalized INH C_max and AUC were statistically higher than those of patients with TB. No significant differences were found in dose-normalized C_max and AUC between adults with TB and adults with TB/HIV; however, the AUC in pediatric patients was significantly different between patients with TB and patients with TB/HIV. In addition, no significance was observed comparing the dose-normalized C_max and AUC of pediatric patients with TB and TB/HIV with their respective adult counterparts. Dose-normalized INH C_max and AUC in patients with fast and intermediate NAT2 were significantly lower than in patients with slow NAT2.

IMPLICATIONS

The current recommended dosages of INH were found to produce less drug exposure in patients with TB when compared with healthy volunteers. NAT2 polymorphism greatly impacts the PK properties of INH; hence, testing for acetylator status is highly recommended, and therapeutic drug monitoring would help reduce INH toxicity.

Pediatric TB Management under RNTCP: What and Why?

Childhood tuberculosis does not get the attention it deserves, both in the general child health services and the TB specific services. The difficulty in identification of the organism due to lack of proper sample as well as lower sensitivity of the smear, made it harder to detect cases with ease in the community. Newer diagnostic methods like cartridge based nucleic acid amplification tests (CBNAAT) and line probe assays (LPA) have the capacity to rapidly identify Mycobacterium tuberculosis with an improved sensitivity over the smear testing and have been employed under Revised National Tuberculosis Control Programme (RNTCP) across the country. As the symptoms suggestive of TB are very common and overlapping, the final yield of TB testing is better if the microbiological confirmation is done on good quality specimen from cases suspected of TB based on clinical and radiological abnormalities. Newer tests also provide simultaneous detection of much critical Rifampicin resistance. A Rifampicin resistant case is not only unlikely to respond to first-line standard therapy but such a treatment can result in further amplification of resistance to other companion drugs. Prevention of spread of the drug resistant disease thus requires that the treatment is guided by universal drug sensitivity testing (U-DST) of all TB cases. Furthermore, several changes have come up in the treatment of TB and are discussed. The dosages of anti TB drugs have been revised upwardly for optimal drug levels and now the fixed drug combinations are used under RNTCP. With the awareness about high initial Isoniazid (INH) resistance and its contribution to failure of retreatment regime, a companion third drug (Ethambutol) has been added to the continuation phase of the first-line therapy. The standard retreatment regime, better known as category II therapy, has been replaced by specific therapy as per the resistance pattern detected. The TB control activities have thus evolved a lot and the present article discusses the evolution and the current status of diagnostics and therapy of TB in children.

Intensified antibiotic treatment of tuberculosis meningitis

INTRODUCTION

Meningitis is the most severe manifestation of tuberculosis, resulting in death or disability in over 50% of those affected, with even higher morbidity and mortality among patients with HIV or drug resistance. Antimicrobial treatment of Tuberculous meningitis (TBM) is similar to treatment of pulmonary tuberculosis, although some drugs show poor central nervous system penetration. Therefore, intensification of antibiotic treatment may improve TBM treatment outcomes. Areas covered: In this review, we address three main areas: available data for old and new anti-tuberculous agents; intensified treatment in specific patient groups like HIV co-infection, drug-resistance, and children; and optimal research strategies. Expert commentary: There is good evidence from preclinical, clinical, and modeling studies to support the use of high-dose rifampicin in TBM, likely to be at least 30 mg/kg. Higher dose isoniazid could be beneficial, especially in rapid acetylators. The role of other first and second line drugs is unclear, but observational data suggest that linezolid, which has good brain penetration, may be beneficial. We advocate the use of molecular pharmacological approaches, physiologically based pharmacokinetic modeling and pharmacokinetic-pharmacodynamic studies to define optimal regimens to be tested in clinical trials. Exciting data from recent studies hold promise for improved regimens and better clinical outcomes in future.

Rifampin vs. rifapentine: what is the preferred rifamycin for tuberculosis?

INTRODUCTION

One-third of the world's population is infected with Mycobacterium tuberculosis (M.tb.). Latent tuberculosis infection (LTBI) can progress to tuberculosis disease, the leading cause of death by infection. Rifamycin antibiotics, like rifampin and rifapentine, have unique sterilizing activity against M.tb. What are the advantages of each for LTBI or tuberculosis treatment? Areas covered: We review studies assessing the pharmacokinetics (PK), pharmacodynamics (PD), drug interaction risk, safety, and efficacy of rifampin and rifapentine and provide basis for comparing them. Expert commentary: Rifampin has shorter half-life, higher MIC against M.tb, lower protein binding, and better distribution into cavitary contents than rifapentine. Drug interactions for the two drugs maybe similar in magnitude. For LTBI, rifapentine is effective as convenient, once-weekly, 12-week course of treatment. Rifampin is also effective for LTBI, but must be given daily for four months, therefore, drug interactions are more problematic. For drug-sensitive tuberculosis disease, rifampin remains the standard of care. Safety profile of rifampin is better-described; adverse events differ somewhat for the two drugs. The registered once-weekly rifapentine regimen is inadequate, but higher doses of either drugs may shorten the treatment duration required for effective management of TB. Results of clinical trials evaluating high-dose rifamycin regimens are eagerly awaited.

Pharmacokinetics of the First-Line Antituberculosis Drugs in Ghanaian Children with Tuberculosis with or without HIV Coinfection

Although human immunodeficiency virus (HIV) coinfection is the most important risk factor for a poor antituberculosis (anti-TB) treatment response, its effect on the pharmacokinetics of the first-line drugs in children is understudied. This study examined the pharmacokinetics of the four first-line anti-TB drugs in children with TB with and without HIV coinfection. Ghanaian children with TB on isoniazid, rifampin, pyrazinamide, and ethambutol for at least 4 weeks had blood samples collected predose and at 1, 2, 4, and 8 hours postdose. Drug concentrations were determined by validated liquid chromatography-mass spectrometry methods and pharmacokinetic parameters calculated using noncompartmental analysis. The area under the concentration-time curve from 0 to 8 h (AUC0-8), maximum concentration (Cmax), and apparent oral clearance divided by bioavailability (CL/F) for each drug were compared between children with and without HIV coinfection. Of 113 participants, 59 (52.2%) had HIV coinfection. The baseline characteristics were similar except that the coinfected patients were more likely to have lower weight-for-age and height-for-age Z scores (P < 0.05). Rifampin, pyrazinamide, and ethambutol median body weight-normalized CL/F values were significantly higher, whereas the plasma AUC0-8 values were lower, in the coinfected children than in those with TB alone. In the multivariate analysis, drug dose and HIV coinfection jointly influenced the apparent oral clearance and AUC0-8 for rifampin, pyrazinamide, and ethambutol. Isoniazid pharmacokinetics were not different by HIV coinfection status. HIV coinfection was associated with lower plasma exposure of three of the four first-line anti-TB drugs in children. Whether TB/HIV-coinfected children need higher dosages of rifampin, pyrazinamide, and ethambutol requires further investigation. (This study has been registered at ClinicalTrials.gov under identifier NCT01687504.).

The challenges of pharmacokinetic variability of first-line anti-TB drugs

INTRODUCTION

Inter-individual variations in the pharmacokinetics (PK) of anti-TB drugs are known to occur, which could have important therapeutic implications in patient management. Areas covered: We compiled factors responsible for PK variability of anti-TB drugs reported from different settings that would give a better understanding about the challenges of PK variability of anti-TB medications. We searched PubMed data base and Google scholar from 1976 to the present using the key words 'Pharmacokinetics', 'pharmacokinetic variability', 'first-line anti-TB therapy', 'Rifampicin', 'Isoniazid', 'Ethambutol', 'Pyrazinamide', 'food', 'nutritional status', 'HIV', 'diabetes', 'genetic polymorphisms' and 'pharmacokinetic interactions'. We also included abstracts from scientific meetings and review articles. Expert commentary: A variety of host and genetic factors can cause inter-individual variations in the PK of anti-TB drugs. PK studies conducted in various settings have adopted different designs, PK sampling time points, drug estimation methodologies. Hence comparison and interpretation of these results should be done with caution More phamacogenomic studies in different patient populations are needed for further understanding.