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Effects of calcium entry blocker (nicardipine) tocolysis rhesus macaques: Fetal plasma concentrations and cardiorespiratory changes

Research output: Contribution to journalArticlepeer-review

Abstract

Tocolytic doses of nicardipine, a dihydropyridine calcium entry blocker, were administered to chronically catheterized rhesus monkeys between days 128 and 132 of gestation. During periods of spontaneous uterine contractility, a 500 µg nicardipine bolus was injected intravenously, and this was followed by continuous infusion (6 µg/kg/min) to the mother for 1 hour. Uterine activity (amniotic fluid pressure) and maternal heart rate and blood pressure were monitored continuously. Paired maternal and fetal blood samples were drawn at frequent intervals to monitor pH, PCO2, PCO2, and plasma nicardipine concentrations. Peak maternal nicardipine concentrations ranged from 175 to 865 ng/ml while peak fetal levels ranged from 7 to 35 ng/ml. Fetal heart rate and blood pressure were unaffected. However, fetuses became acidotic (pH 7.26 ± 0.01 versus 7.33 ± 0.01) and hypoxemic (PO216.0 ± 3.2 versus 24.5 ± 2.0 mm Hg) after maternal nicardipine treatment (p < 0.01). Despite the fact that maternal nicardipine treatment exerted a significant tocolytic effect, the undesirable fetal side effects are of concern and deserve further investigation.

Original languageEnglish
Pages (from-to)1482-1486
Number of pages5
JournalAmerican Journal of Obstetrics and Gynecology
Volume157
Issue number6
DOIs
StatePublished - 1987

ASJC Scopus Subject Areas

  • Obstetrics and Gynecology

Keywords

  • Uterine contractility
  • fetus
  • nicardipine
  • rhesus monkey

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