Pharmacokinetics | Development of Voriconazole Pharmacokinetics and Metabolism in Children and Adolescents
Pharmacokinetics research study
What is the primary objective of this study?
The death rate in children from the invasive fungal infection called aspergillosis is more than 50%. Voriconazole is the first-line therapy for this infection. In a previous publication the investigators have shown a highly significant relationship between voriconazole plasma concentrations and survival. However, voriconazole dosing is currently poorly established, and plasma drug exposure varies between children by 400% or more, even after intravenous dosing. The objective of this study is to investigate the reasons for this variability in voriconazole pharmacokinetics (PK).In two studies, the investigators will enroll 80 children/adolescents receiving oral or intravenous voriconazole, divided by age under 2 years (n=15), and 2-18 years (n=65). From each patient the investigators will collect the following: 1) a blood sample for detection of several genetic changes known to affect drug metabolizing enzyme (DME) activity; 2) up to 9 blood samples after a voriconazole dose for measurement of voriconazole (\"PK sampling\"); 3) follow-up samples after each PK sampling visit if necessary to adjust the dose so that voriconazole concentrations in the blood are satisfactory (known as therapeutic drug monitoring or TDM). At the time of the voriconazole dose prior to the PK sampling, we will also give single IV or oral (corresponding to the route of voriconazole administration) low doses of esomeprazole (an antacid), midazolam (a sedative), and ranitidine (an antacid) as a cocktail to test or probe DME activity. All of these medications are used commonly in children already. The investigators will estimate DME activity or phenotype using ratios of probe drug metabolite to parent drug concentrations, while simultaneously quantifying the amount of DME genetic material (mRNA) and protein in white blood cells. The investigators will test associations between DME activity, mRNA, protein, voriconazole PK, age, sex, and degree of illness. The investigators will also use a computer program to integrate all these data to develop a comprehensive model that will predict blood concentrations of voriconazole in children of all ages, as well as assist physicians and pharmacists to dose voriconazole more accurately.The total study duration for each subject will be until after the TDM follow up visit, generally about one week.
Who is eligible to participate?
Inclusion Criteria: 1. Participants will be enrolled before their 18th birthday. 2. Participant/parent/legal guardian must be able and willing to provide signed informed consent. 3. Laboratory values obtained within 7 days prior to study entry (obtained for clinical purposes) 1. Hemoglobin ≥ 7.0 g/dL (transfusion dependence acceptable) 2. Aspartate aminotransferase (AST) (SGOT), alanine aminotransferase (ALT) (SGPT), and total bilirubin ≤ 5 X upper limit of age-appropriate normal (ULN) 3. Serum creatinine ≤ 3 X ULN Exclusion Criteria: 1. Pregnancy 2. Active substance abuse or other psychiatric illness that would prevent adherence to the study protocol. Investigators will not record this information in the screening log, and the information will be obtained from existing documents in the medical record only. 3. Known hypersensitivity or intolerance to study medications 4. Not expected to survive >1 week. 5. Weight < 4.5 kg (blood volume draw limitations)
Which medical condition, disease, disorder, syndrome, illness, or injury is researched?
Interventions can include giving participants drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available or noninvasive approaches such as surveys, education, and interviews.
Drug:Midazolam/Ranitidine/EsomeprazoleEach of the three drugs will be given at 10% of their usual doses for age/weight.
Research studies and clinical trials typically have two or more research arms. An arm is a group of people who receive the same treatment in the study.
Midazolam/Ranitidine/EsomeprazoleAll enrolled subjects will have a study pharmacokinetic visit where they will be given the above cocktail of drugs along with their clinically indicated voriconazole dose, followed by blood sampling over the next 12 hours.
Start Date: September 2012
Completed Date: April 22, 2015
Primary Outcome: Voriconazole steady-state pharmacokinetics
Secondary Outcome: Voriconazole drug metabolizing enzyme activity
Study sponsors, principal investigator, and references
Principal Investigator: Michael N Neely, MD
Lead Sponsor: Children's Hospital Los Angeles
Collaborator: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
Hope WW, Vanguilder M, Donnelly JP, Blijlevens NM, Brüggemann RJ, Jelliffe RW, Neely MN. Software for dosage individualization of voriconazole for immunocompromised patients. Antimicrob Agents Chemother. 2013 Apr;57(4):1888-94. doi: 10.1128/AAC.02025-12. Epub 2013 Feb 4.