Pharmacokinetics and clinical effects of intramuscular scopolamine plus morphine A comparison of two injection sites
Article first published online: 30 DEC 2008
Copyright © 1998 Acta Anaesthesiol Scand
Acta Anaesthesiologica Scandinavica
Volume 42, Issue 3, pages 323–328, March 1998
How to Cite
Kentala, E., Scheinin, H., Kaila, T., Seppälä, T. and Kanto, J. (1998), Pharmacokinetics and clinical effects of intramuscular scopolamine plus morphine A comparison of two injection sites. Acta Anaesthesiologica Scandinavica, 42: 323–328. doi: 10.1111/j.1399-6576.1998.tb04924.x
- Issue published online: 30 DEC 2008
- Article first published online: 30 DEC 2008
- Recieved 13 June 1997 accepted 23 September 1997
Background: Intramuscular scopolamine plus morphine pre-medication is traditionally used when prominent sedative or antisialogogue effect is needed. Knowledge of the pharmacokinetics of scopolamine is limited due to low plasma concentrations found after therapeutic doses. This investigation compares the pharmacokinetics and the clinical responses of this drug combination injected into two commonly used injection sites.
Methods: Twelve ASA class 1 patients scheduled for minor surgery under spinal anaesthesia received scopolamine 6 μg/kg plus morphine 200 μg/kg injected in either deltoid (group D, n=6) or gluteal (group G, n=6) muscle.
Results: The peak plasma concentrations of scopolamine after deltoid or gluteal injection (2.2 vs 1.6 μg/1) and the time they were reached (17 vs 19 min) were comparable. The absorption of morphine was similar in both groups (Tmax 16 min), but the peak plasma concentrations were higher after deltoid injection (71 vs 49 μg/1). The individual variation in the elimination half-lives of both scopolamine and morphine was smaller after deltoid injection (T½ scopolamine 1.9±0.7 vs 2.1±1.1 h, morphine 1.3±0.7 vs 2.3±1.5 h). Moderate slowing (25%) of heart rate was found in both groups. A heavy sedation and antisialogogue effect (VAS) was found in both groups with faster occurrence of maximal effect in group D (60 vs 120–180 min).
Conclusion: More predictable pharmacokinetics and clinical effects of intramuscular scopolamine plus morphine premedication can be achieved after an injection into deltoid muscle.