title: Pharmacokinetics and clinical effects of intramuscular scopolamine plus morphine. A comparison of two injection sites.
abstract: BACKGROUND
  Intramuscular scopolamine plus morphine premedication 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 micrograms/kg plus morphine 200 micrograms/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 micrograms/l) 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 micrograms/l). The individual variation in the elimination half-lives of both scopolamine and morphine was smaller after deltoid injection (T1/2 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).
  
  
  CONCLUSIONS
  More predictable pharmacokinetics and clinical effects of intramuscular scopolamine plus morphine premedication can be achieved after an injection into deltoid muscle.
authors.affiliation: Department of Anaesthesiology, University of Turku, Finland.
authors.forename: E
authors.initials: E
authors.lastname: Kentala
authors.forename: H
authors.initials: H
authors.lastname: Scheinin
authors.forename: T
authors.initials: T
authors.lastname: Kaila
authors.forename: T
authors.initials: T
authors.lastname: Seppälä
authors.forename: J
authors.initials: J
authors.lastname: Kanto
mesh_terms: D000775:Anesthesia, Spinal; D004338:Drug Combinations; D006801:Humans; D007273:Injections, Intramuscular / Q000379:methods; D008297:Male; D009020:Morphine / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D012463:Saliva / Q000187:drug effects; D012601:Scopolamine / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D013514:Surgical Procedures, Operative
chemical_list: D004338:Drug Combinations; D009020:Morphine; D012601:Scopolamine