title: Pharmacokinetics of three doses of epidural ropivacaine during hysterectomy and comparison with bupivacaine.
abstract: OBJECTIVE
  Ropivacaine is a new long-acting aminoamide local anaesthetic, structurally related to bupivacaine. The clinical efficacy of 125 mg, 187.5 mg and 250 mg ropivacaine have been reported and compared with 125 mg bupivacaine for epidural analgesia during hysterectomy. In the pharmacokinetic part of this study the objectives were to 1) determine the dose proportionality in the pharmacokinetics of epidural ropivacaine, and 2) compare the pharmacokinetics of 125 mg ropivacaine and 125 mg bupivacaine.
  
  
  METHODS
  In a randomized, double-blind controlled study, patients received one of four treatment regimens with ropivacaine (125, 187.5 or 250 mg) or bupivacaine (125 mg) as a 25 ml epidural bolus administered over three minutes. Peripheral venous blood samples were collected over 24 hr for ropivacaine or bupivacaine quantification using gas chromatography with nitrogen sensitive detection. Pharmacokinetic variables were derived from plasma concentration-time curve data.
  
  
  RESULTS
  Fifty two women entered the study. Demographic characteristics were similar among groups. Six patients were excluded due to inadequate sensory block or an insufficient number of plasma samples. The peak plasma concentration (Cmax) of ropivacaine and the total area under the plasma concentration-time curve (AUC) increased proportionally with the dose. Apparent plasma clearance (CL) and the terminal half-life (t1/2) were similar in the three ropivacaine groups. When compared with the 125 mg ropivacaine group, the bupivacaine group had a longer terminal half life (P < 0.05).
  
  
  CONCLUSIONS
  Epidural ropivacaine displays dose-proportional pharmacokinetic behaviour for doses of 125 mg to 250 mg. Ropivacaine has a shorter terminal half-life than bupivacaine.
authors.affiliation: Department of Anaesthesia, Toronto Hospital, Ontario, Canada.
authors.forename: A N
authors.initials: AN
authors.lastname: Sandler
authors.forename: E
authors.initials: E
authors.lastname: Arlander
authors.forename: B T
authors.initials: BT
authors.lastname: Finucane
authors.forename: A
authors.initials: A
authors.lastname: Taddio
authors.forename: V
authors.initials: V
authors.lastname: Chan
authors.forename: A
authors.initials: A
authors.lastname: Milner
authors.forename: S O
authors.initials: SO
authors.lastname: Callahan-Enright
authors.forename: M
authors.initials: M
authors.lastname: Friedlander
authors.forename: D
authors.initials: D
authors.lastname: Muzyka
mesh_terms: D000328:Adult; D000577:Amides / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D015360:Analgesia, Epidural; D000767:Anesthesia, Epidural; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D002045:Bupivacaine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D002849:Chromatography, Gas; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006207:Half-Life; D006801:Humans; D007044:Hysterectomy; D016014:Linear Models; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D002045:Bupivacaine