Summary
After administration of clenbuterol 80 µg p.o., a β-adrenoceptor agonist, the concentrations of (14C-labelled)clenbuterol in fetus, placenta and maternal plasma in 9 patients at 9–12 weeks gestation were measured during therapeutic abortion. The time interval between the administration and abortion ranged from 120 to 280 min. The mean concentrations of clenbuterol in maternal plasma, fetus and placenta were 0.37 (range 0.22–0.56), 0.32 (0.14–0.48) and 0.91 (0.12–1.73) ng equivalents per ml or per gram of tissue wet weight. The mean concentration ratio of clenbuterol between fetus and maternal plasma was 0.84 (6 cases); it did not vary with time. The concentration of clenbuterol in three amniotic fluid samples ranged from 0.06 to 0.18 ng/ml (mean 0.11). Maternal plasma concentrations showed wide variability of the pharmacokinetic phase at the time of abortion. The studies indicate that clenbuterol crosses the placenta early in human pregnancy and that it accumulates in the placenta.
Similar content being viewed by others
References
Allonen H, Kanto J, Iisalo E (1977) The foeto-maternal distribution of digoxin in early human pregnancy. Acta Pharmacol Toxicol 39: 477–480
Arzneimittel-Forschung (Drug Res.) (1976) Themanummer: Clenbuterol. 26: Nr. 7a
Greiss FC Jr (1972) Differential reactivity of the myoendometrial and placental vasculatures. Am J Obstet Gynecol 112: 20–30
Kauppila A, Kuikka J, Tuimala R (1978) Effect of fenoterol and isoxsuprine on myometrial and intervillous blood flow during late pregnancy. Obstet Gynecol 52: 558–562
Krauer B, Krauer F, Hytten FE (1980) Drug disposition and pharmacokinetics in the maternal-placental-fetal unit. Pharmacol Ther 10: 301–328
McMurphy DM, Boreus LO (1971) Studies on the pharmacology of the perfused human fetal ductus arteriosus. Am J Obstet Gynecol 109: 937–942
Miller FC, Nochimson DJ, Paul RH, Hon EH (1976) Effects of ritodrine hydrochloride on uterine activity and the cardiovascular system in toxemic patients. Obstet Gynecol 47: 50–55
Mirkin BL (1975) Perinatal pharmacology: Placental transfer, fetal localization, and neonatal disposition of drugs. Anesthesiology 43: 156–170
Van Petten GR (1975) Pharmacology and the fetus. Br Med Bull 31: 75–79
Waddell WJ, Marlowe GC (1976) Disposition of drugs in the fetus. In: Mirkin B (ed) Perinatal pharmacology and therapeutics. Academic Press, New York, pp 119–268
Zimmer A, Bucheler A (1976) Einmalapplikation, Mehrfachapplikation und Metabolitenmuster von Clenbuterol beim Menschen. Arzneim Forsch 26: 1446–1450
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Pelkonen, O., Tuimala, R. & Kauppila, A. Placental transfer of clenbuterol early in human pregnancy. Eur J Clin Pharmacol 22, 403–406 (1982). https://doi.org/10.1007/BF00542542
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00542542