Rifampin and Efavirenz Interactions in Older Children

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01704144
Recruitment Status : Unknown
Verified September 2012 by The Miriam Hospital.
Recruitment status was:  Recruiting
First Posted : October 11, 2012
Last Update Posted : October 17, 2012
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
Information provided by (Responsible Party):
The Miriam Hospital

Brief Summary:
Efavirenz is an essential component of HIV treatment in children aged 3 years or older on anti-tuberculosis (anti-TB) treatment. However, the appropriate efavirenz dose during anti-TB treatment remains unclear. Rifampin (an anti-TB drug) increases the activity of the drug metabolizing enzymes that breakdown efavirenz, which may lead to low blood levels of efavirenz and treatment failure during cotreatment. The drug-to-drug interactions between the HIV and anti-TB drugs also vary between individuals based on genetic factors. This study will investigate the effects of anti-TB treatment, as well as drug-gene interactions on the blood concentrations of efavirenz in children with HIV and TB infections. Such data could enhance optimization of efavirenz dosage or selection of alternate regimens in some children.

Condition or disease
HIV Tuberculosis

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Detailed Description:

Efavirenz-based antiretroviral therapy (ART) is the preferred regimen in children older than 3 years on rifampin-containing anti-TB therapy. Efavirenz trough plasma concentrations below 1000 ng/mL have been associated with increased risk of virologic failure among HIV-infected adults, while concentrations above 4000 ng/mL have been associated with risk of central nervous system side effects. Efavirenz is primarily metabolized by hepatic CYP2B6, with secondary contributions from CYP2A6. On average, rifampin co-administration causes a 26% reduction in efavirenz plasma exposure but some individuals have paradoxically elevated efavirenz concentrations with co-administration in adult pharmacokinetic studies. The inter-individual variability in the drug-to-drug interactions suggest that efavirenz dose adjustment with concomitant anti-TB therapy may not be necessary in some patients. In children, there is very limited data on the pharmacokinetic interactions between rifampin-containing TB treatment and efavirenz. To our knowledge, there is only one published study in children to date. Among 15 TB/HIV co-infected children treated with standard efavirenz-based active antiretroviral therapy and rifampin-containing TB treatment, a wide inter-patient variability in efavirenz concentration as well as a bimodal distribution of efavirenz trough concentrations were observed. Overall, rifampin-containing anti-TB treatment had no significant influence on the mean change in efavirenz concentration in the study population as a whole, but 60% and 53% of children had efavirenz trough concentration < 1000 ng/mL during and after anti-TB, respectively. This data suggest that current dosing of efavirenz may be suboptimal in a large proportion of children irrespective of anti-TB therapy. To overcome the risk of under-dosing of efavirenz especially with concurrent anti-TB treatment, the WHO recommended prescribing the maximum dose for each weight-band when efavirenz is coadministered with anti-TB treatment. This study seeks to evaluate whether the current dosing of efavirenz provides adequate efavirenz concentrations in children, as well as explore how genetic factors influence efavirenz pharmacokinetics with concomitant anti-TB treatment. The specific hypotheses to be tested are:

  1. At the population level, efavirenz plasma concentrations in TB/HIV co-infected children who are treated with the maximized weight-based efavirenz dosage during rifampin-containing anti-TB therapy will be comparable to concentrations in HIV-infected children receiving ART without anti-TB treatment.
  2. Co-treatment with rifampin- and efavirenz-containing therapies will lead to substantially decreased (by at least 40%) efavirenz concentration in the children with CYP2B6 extensive but not in those with intermediate or slow metabolizer genotypes.

A two-arm, as well as a two-period pharmacokinetic study in HIV-infected children with and without TB will be performed at the Komfo Anokye Teaching Hospital (KATH), Kumasi, Ghana. Eligible participants will include children aged 3 - 14 years with HIV with or without TB coinfection, ART-naïve and eligible to initiate ART. The ART regimen will consist of the WHO recommended weight-band dosing of efavirenz (10-13.9kg - 200 mg; 14-24.9kg - 300mg; 25-39.9kg - 400 mg and > 40Kg - 600 mg), plus ZDV 180 - 240 mg/m2 and 3TC 4 mg/kg twice daily. Tenofovir may be used in place of ZDV. Standard anti-TB therapy will be prescribed to the co-infected patients and will start immediately upon TB diagnosis.

A complete medical history, physical examination, and staging of HIV disease will be performed before initiation of ART. Baseline measurements prior to initiation of ART will include CBC, blood urea nitrogen, creatinine, LFTs, CD4 cell count determination and plasma HIV-1 RNA level. Weeks 12 and 24 CD4 cell count and plasma HIV-1 RNA will obtained at scheduled follow-up. Pharmacokinetic sampling will be performed at week 4 of ART in both arms and at 4 weeks after anti-TB treatment in the co-infected group. At each sampling time, 3 mL of blood will be collected into an EDTA tube. Blood samples will be collected at times 0 2, 8, 12 and 24 hours post-dose for determination of efavirenz concentrations. Efavirenz concentrations in plasma will be measured using a HPLC-MS. After sample analysis, a data set will be constructed. Anticipated covariates included in this data set to be explored will include age, sex, weight, relevant drug-metabolizing enzyme genotype, TB therapy status (on/off), and CD4 cell count. Nonlinear mixed-effects modeling (using NONMEM, version VI) will be used to estimate pharmacokinetic parameters (CL/F, V/F, AUC, Cmin, Cmax, elimination rate constant), inter-individual error, and residual error. Results of this population analysis may be used to simulate alternative efavirenz dosing strategies in this TB/HIV co-infected population, or in relevant sub-populations with variant PK/pharmacogenetics.

Study Type : Observational
Estimated Enrollment : 160 participants
Observational Model: Cohort
Time Perspective: Prospective
Official Title: Effect of Rifampin-containing Anti-TB Treatment on Efavirenz Pharmacokinetics in HIV/TB Co-infected Children Aged 3 - 14 Years
Study Start Date : October 2012
Estimated Primary Completion Date : May 2017
Estimated Study Completion Date : May 2017

Resource links provided by the National Library of Medicine

Primary Outcome Measures :
  1. Area under time curve from time 0-24 hours(AUC0-24h) of efavirenz [ Time Frame: At week of 4 of HIV therapy ]
    Compare efavirenz AUC0-24h between HIV-infected children without TB and those with TB on rifampin-containing anti-TB therapy in co-infected patients

Secondary Outcome Measures :
  1. Number of children with grade 3 or 4 liver enzymes elevations compared to baseline, new onset of skin rash, nausea, vomiting or treatment modification due to drug side effects [ Time Frame: up to week 24 of therapy ]
    Compare frequency of adverse events as a measure of safety and tolerability between HIV-infected children with and without TB coinfection

  2. Number of children with efavirenz 24-hour post-dose concentration (C24h) < 1000 ng/mL [ Time Frame: At week 4 of therapy ]
    Relationship between clinical factors (weight, gender, nutritional status) as well as genetic factors (CYP2B6 516G>T, as well as CYP3A4, ABCB1, CAR and PXR polymorphisms) and efavirenz AUC0-24h and efavirenz C24h will be investigated

  3. Number of children who discontinue efavirenz therapy due to drug side effects [ Time Frame: Up to week 24 of HIV therapy ]
    Relationship between clinical factors (weight, gender, nutritional status) as well as genetic factors (CYP2B6 polymorphisms) and treatment modification due to drug side effects in the combined study population

  4. Trough concentration (C24h) of efavirenz [ Time Frame: At week 4 of therapy ]
    Compare efavirenz C24h between HIV-infected children without TB and those with TB, as well as in the absence of and presence of rifampin-containing anti-TB therapy in co-infected patients

  5. AUC, Cmax and clearance of efavirenz on and off rifampin-containing anti-Tb therapy in HIV/TB co-infected patients [ Time Frame: at week 24 of therapy ]

Biospecimen Retention:   Samples With DNA
EDTA plasma Whole blood DNA

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Ages Eligible for Study:   3 Years to 14 Years   (Child)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
HIV-infected children with and with TB aged 3 to 14 years old

Inclusion Criteria:

  1. Children with active TB with or without HIV co-infection. Active TB diagnosis defined by clinical criteria consistent with active TB and/or a positive AFB smear or mycobacterial culture.
  2. Aged 3 months to 14 years old
  3. Are available for follow-up until completion of TB treatment and/or achievement of a study endpoint like discontinuation of therapy, and/or pharmacokinetic sampling.

Exclusion Criteria:

  1. Unable to obtain informed signed consent parent(s) or legal guardian
  2. Have AIDS-related opportunistic infections other than TB, history of or proven acute hepatitis within 30 days of study entry, persistent vomiting, or diarrhea
  3. Hemoglobin < 6 g/dl, white blood cells < 2500/mm3, serum creatinine > 1.5 mg/dl, AST and ALT > 2X upper limit of normal.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01704144

Contact: Awewura Kwara, MD, MPH&TM 4017932463
Contact: Sampson Antwi, MBChB +233265812061

Komfo Anokye Teaching Hospital Recruiting
Kumasi, Ghana
Contact: Sampson Antwi, MBchB    +233265812061   
Contact: Anthony Enimil, MBChB    +233208164433   
Sponsors and Collaborators
The Miriam Hospital
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
Principal Investigator: Awewura Kwara, MD, MPH&TM The Miriam Hospital

Responsible Party: The Miriam Hospital Identifier: NCT01704144     History of Changes
Other Study ID Numbers: PK-PTBHIV03
R01HD071779 ( U.S. NIH Grant/Contract )
First Posted: October 11, 2012    Key Record Dates
Last Update Posted: October 17, 2012
Last Verified: September 2012

Keywords provided by The Miriam Hospital:
Drug-drug interactions
Drug-gene interactions

Additional relevant MeSH terms:
Mycobacterium Infections
Actinomycetales Infections
Gram-Positive Bacterial Infections
Bacterial Infections
Reverse Transcriptase Inhibitors
Nucleic Acid Synthesis Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Anti-Retroviral Agents
Antiviral Agents
Anti-Infective Agents
Cytochrome P-450 CYP2C9 Inhibitors
Cytochrome P-450 Enzyme Inhibitors
Cytochrome P-450 CYP2C19 Inhibitors
Cytochrome P-450 CYP2B6 Inducers
Cytochrome P-450 Enzyme Inducers
Cytochrome P-450 CYP3A Inducers
Antibiotics, Antitubercular
Antitubercular Agents
Anti-Bacterial Agents
Leprostatic Agents
Cytochrome P-450 CYP2C8 Inducers
Cytochrome P-450 CYP2C19 Inducers
Cytochrome P-450 CYP2C9 Inducers