Rifapentine pharmacokinetics in adolescents.
OBJECTIVE
Determination of rifapentine pharmacokinetics in healthy adolescent children.


METHODS
Prospective Phase II clinical trial.


METHODS
Clinical research center within a university children's hospital.


METHODS
Twelve subjects ranging in age from 12 to 15 years, male and female.


METHODS
A single oral dose of rifapentine was administered to healthy adolescent volunteers, 450 mg if <45 kg or 600 mg if > or =45 kg. Blood was collected at serial intervals (0, 2, 3, 4, 5, 6, 8, 12, 18, 24, 48 and 72 h postdose). Subjects were observed for adverse effects during the period of study.


METHODS
High pressure liquid chromatography was used to measure the plasma concentration of rifapentine and 25-desacetyl rifapentine in each blood sample. For each subject a plot of mean plasma concentration vs. time data for rifapentine and its metabolite (i.e. 25-desacetyl rifapentine) were created. Subsequently model-independent methods were used to determine the pharmacokinetic profiles for each subject.


RESULTS
All subjects tolerated rifapentine without adverse effects. The 2-h postdose plasma concentrations of rifapentine (6.59 to 9.05 microg/ml) and 25-desacetyl rifapentine (0.57 to 2.64 microg/ml) far exceeded the MIC of Mycobacterium tuberculosis to rifapentine (approximately 0.12 microg/ml). The combination of a high Cmax (rifapentine, 9.95 to 18.63 microg/ml; 25-desacetyl rifapentine, 3.73 to 7.46 microg/ml) and lengthy terminal elimination phase t1/2 (rifapentine, 10 to 23 h; 25-desacetyl rifapentine, 14 to 35 h) resulted in potentially effective plasma concentrations of both compounds that persisted for at least 48 h in most subjects.


CONCLUSIONS
A well-tolerated oral rifapentine dose produced rapid and sustained plasma drug concentrations in adolescents that should effectively treat infections caused by M. tuberculosis. Rifapentine pharmacokinetics appears to be similar in adolescent and adult populations.
Marshall
J D
JD
Department of Pediatrics, University of Missouri-Kansas City, USA. jmarshall@cmh.edu
Abdel-Rahman
S
S
Johnson
K
K
Kauffman
R E
RE
Kearns
G L
GL
D000293:Adolescent; D000904:Antibiotics, Antitubercular / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012293:Rifampin / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics
D000904:Antibiotics, Antitubercular; D012293:Rifampin; C018421:rifapentine