Placental Transfer and Pharmacokinetics of Atropine after a Single Maternal Intravenous and Intramuscular Administration

Abstract

The placental transfer and pharmacokinetics of atropine were studied in 44 healthy parturients undergoing caesarean section. The concentrations in the plasma were determined by a new radioimmunoassay after intravenous (n=32) or after intramuscular (n=12) administration of 0.01 mg/kg of atropine. A fast placental transfer with apparent foetal uptake of the drug was found after intravenous injection. There was also a difference in the umbilical vein and artery concentrations after intramuscular administration. The maternal pharmacokinetics of i.v. atropine obeyed and two-compartment open model with a fast distribution phase (mean ta1/2=1.02 min) and quite fast elimination (t1/2=2.56h). The total apparent volume of distribution was 1.01/kg and the total plasma clearance 6.36 ml/min/kg. The mean peak maternal plasma levels after i.m. atropine administration were found at 1.59 h and the mean calculated half-life of elimination was then 2.1 h. No atropine was found in the amniotic fluid.

Intrauterine fetal bradycardia after accidental administration of the anesthetic agent in the subdural space during epidural labor analgesia -A case report-

“…Unlike atropine, glycopyrrolate does not cross the placenta; therefore, it does not cause fetal tachycardia [11]. In healthy parturients, the plasma, placental artery, and vein concentrations of atropine were determined after IV or intramuscular administration of 0.01 mg/kg atropine, showing faster distribution and elimination of atropine and higher mean peak maternal plasma levels for IV administration than those observed for intramuscular administration [12]. Therefore, IV atropine is more effective in emergencies like fetal distress [13].…”

Pharmacokinetics and Clinical Effects of Scopolamine in Caesarean Section Patients

“…In many aspects, the pharmacokinetics of scopolamine appear to be similar to those of atropine after intravenous injection (Berghem et a/. But following intramuscular injection, scopolamine has a faster absorption rate, when compared to atropine (Berghem et al 1980;Kanto et al 1981;Virtanen et d. 1982). But following intramuscular injection, scopolamine has a faster absorption rate, when compared to atropine (Berghem et al 1980;Kanto et al 1981;Virtanen et d. 1982).…”

Placental and Blood‐CSF Transfer of Orally Administered Diazepam in the same Person

“…Differing from our earlier studies with atropine (Virtanen el al. 1982;Kanto et al 1981Kanto et al & 1987, a reasonably fast penetration of diazepam and its two metabolites through the two biological membranes was found. Diazepam, Ndesmethyldiazepam and to a lesser extent unconjugated oxazepam accumulated on the foetal side of the placenta, apparently due to a higher degree of plasma protein binding in the foetus.…”