TY - BOOK AU - Umans, Jason G TI - Nifedipine pharmacokinetics are influenced by CYP3A5 genotype when used as a preterm labor tocolytic SN - 0735-1631 PY - 2013/// KW - *Cytochrome P-450 CYP3A/ge [Genetics] KW - *Nifedipine/pk [Pharmacokinetics] KW - *Obstetric Labor, Premature/pc [Prevention & Control] KW - *Polymorphism, Genetic KW - *Tocolytic Agents/pk [Pharmacokinetics] KW - Adolescent KW - Adult KW - Alleles KW - Cohort Studies KW - Dose-Response Relationship, Drug KW - Female KW - Gene Expression Regulation KW - Genotype KW - Humans KW - Infant, Newborn KW - Nifedipine/ad [Administration & Dosage] KW - Obstetric Labor, Premature/ge [Genetics] KW - Pharmacogenetics KW - Pregnancy KW - Pregnancy Outcome KW - Prospective Studies KW - Statistics, Nonparametric KW - Tocolytic Agents/ad [Administration & Dosage] KW - Young Adult KW - MedStar Health Research Institute KW - Comparative Study KW - Journal Article KW - Research Support, N.I.H., Extramural N2 - CONCLUSION: CYP3A5 genotype influences the oral clearance of nifedipine in pregnant women. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA; OBJECTIVE: To characterize the pharmacokinetics and pharmacogenetics of nifedipine in pregnancy; RESULTS: Fourteen women had complete data to analyze. Four women (29%) expressed variant CYP3A5; three of these women were also CYP3A4*1B allele carriers. The mean half-life of nifedipine was 1.68 +/- 1.56 hours. The area under the curve from 0 to 6 hours for the women receiving nifedipine every 6 hours was 207 +/- 138 g.h /L. Oral clearance was different between high expressers and low expressers (232.0 +/- 37.8 g/mL versus 85.6 +/- 45.0 g/mL, respectively; p = 0.007); STUDY DESIGN: Pregnant women receiving oral nifedipine underwent steady-state pharmacokinetic testing over one dosing interval. DNA was obtained and genotyped for cytochrome P450 (CYP) 3A5 and CYP3A4*1B. Nifedipine and oxidized nifedipine concentrations were measured in plasma, and pharmacokinetic parameters were compared between those women who expressed a CYP3A5*1 allele and those who expressed only variant CYP3A5 alleles (*3,*6, or *7) UR - http://dx.doi.org/10.1055/s-0032-1323590 ER -