Nifedipine Pharmacokinetics and Pharmacodynamics When Used as a Tocolytic in Acute Threatened Preterm Labour
Status:
Unknown status
Trial end date:
2016-01-01
Target enrollment:
Participant gender:
Summary
Preterm birth is the leading cause of perinatal mortality and morbidity. According to WHO, 15
million children are born prematurely (gestational age < 37 weeks) in the world each year
while 7% of them die because of complications associated with prematurity. Despite constant
improvement of obstetrical care, the number of preterm births has increased over the last
decades and prematurity is still the most frequent cause of prenatal hospitalization in
industrialized countries.
The American College of Obstetricians and Gynecologists as well as the Royal College of
Obstetricians and Gynaecologists recommend nifedipine as a first-line tocolytic in case of
acute threatened preterm labour. Clinical experience show however an important variability in
treatment response among pregnant women. In spite of its large use in obstetrics as a
tocolytic agent, nifedipine is prescribed off-label. As a consequence no international
consensus on optimal dose schedule has so far been proposed.
Small sample size and heterogeneousness of tocolysis administration protocols make it
difficult to compare the little data available on the pharmacokinetics of nifedipine in
pregnant women. Nevertheless an important interindividual variability in concentrations has
been identified (CV=12-76%) but very few studies have investigated the possible reasons of
this variability in pregnant women. Genetic and environmental factors involved in drug
distribution and metabolism (e.g. enzymatic activity, CYP 3A5 genotype) might partially
explain variability in drug levels and therefore differences in treatment response.
The goal of this study is to quantify the variability in nifedipine pharmacokinetics and
identify potential genetic and non-genetic sources of variability in nifedipine
pharmacokinetics in pregnant women. The relationship between concentration and treatment
response will be evaluated and will serve to propose optimal dosage regimen to improve
efficacy and reduce side effects associated with this treatment.