Pharmacokinetics and transplacental transfer of lidocaine and its metabolite for perineal analgesic assistance to pregnant women.

Autor: Cavalli, Ricardo de Carvalho, Lanchote, Vera Lúcia, Duarte, Geraldo, Dantas, Elaine Christine Moisés, de Prado, Maria Fernanda Massoni, de Duarte, Luciana Barros, da Cunha, Sérgio Pereira
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Zdroj: European Journal of Clinical Pharmacology; Oct2004, Vol. 60 Issue 8, p569-574, 6p
Abstrakt: Background: Obstetrical analgesia continues to be challenging to science in the search for safe and effective methods that will permit the use of these procedures allied to improved obstetrical and perinatal results. Objective: The objective of the present study was to investigate the pharmacokinetics and the placental transfer of lidocaine and its metabolite in parturients whose pregnancies were resolved by the vaginal route under perineal analgesia. Patients and methods: The study was conducted on 23 pregnant women who received perineal analgesia with 20 ml 2% lidocaine (400 mg) during the expulsive period of labor. Maternal venous blood samples were obtained from 0 mm to 360 mm after drug administration, and umbilical venous blood was obtained at delivery. Lidocaine and monoethylglycinexylidide (MEGX) were determined using high-performance liquid chromatography. The fetal/maternal ratios of the drugs were determined on the basis of maternal and fetal concentrations at delivery. Results: Maximum lidocaine concentrations at the median times of 15 mm were 3.22 µg/ml. The pharmacokinetic parameters were: half-life t1/2α 24.0 mm, area under the curve (AUC)0-∞ 460.2 µg/mm per ml, t1/2Β 180.0 mm, clearance 12.2 mI/mm per kg and volume distribution 3.1 I/kg. The fetal/maternal ratio for lidocaine at delivery was 0.46, with the latency time between drug administration and delivery being 11.0 mm. Maximum MEGX concentrations at the median time of 90 mm were 229.0 ng/ml. The t1/2 for MEGX was 240 mm, and AUC0-∞ was 82.4 jig mm/mI. Conclusion: Lidocaine administered by the perineal route presented a tmax of 15 mm, significantly lower than when the drug was administered peridurally, revealing that the time between administration and the occurrence of the analgesic effect was shorter. The study demonstrated placental transfer of lidocaine at ratios of about 50% for lidocaine at the time of delivery. The MEGX placental transfer demonstrated fetal concentration higher than the maternal at the time of delivery. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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