title: Influence of gastrointestinal tract disease on pharmacokinetics of lidocaine after intravenous infusion in anesthetized horses.
abstract: OBJECTIVE
  To determine the disposition of lidocaine after IV infusion in anesthetized horses undergoing exploratory laparotomy because of gastrointestinal tract disease.
  
  
  METHODS
  11 horses (mean +/- SD, 10.3 +/- 7.4 years; 526 +/- 40 kg).
  
  
  METHODS
  Lidocaine hydrochloride (loading infusion, 1.3 mg/kg during a 15-minute period [87.5 microg/kg/min]; maintenance infusion, 50 microg/kg/min for 60 to 90 minutes) was administered IV to dorsally recumbent anesthetized horses. Blood samples were collected before and at fixed time points during and after lidocaine infusion for analysis of serum drug concentrations by use of liquid chromatography-mass spectrometry. Serum lidocaine concentrations were evaluated by use of standard noncompartmental analysis. Selected cardiopulmonary variables, including heart rate (HR), mean arterial pressure (MAP), arterial pH, PaCO2, and PaO2, were recorded. Recovery quality was assessed and recorded.
  
  
  RESULTS
  Serum lidocaine concentrations paralleled administration, increasing rapidly with the initiation of the loading infusion and decreasing rapidly following discontinuation of the maintenance infusion. Mean +/- SD volume of distribution at steady state, total body clearance, and terminal half-life were 0.70 +/- 0.39 L/kg, 25 +/- 3 mL/kg/min, and 65 +/- 33 minutes, respectively. Cardiopulmonary variables were within reference ranges for horses anesthetized with inhalation anesthetics. Mean HR ranged from 36 +/- 1 beats/min to 43 +/- 9 beats/min, and mean MAP ranged from 74 +/- 18 mm Hg to 89 +/- 10 mm Hg. Recovery quality ranged from poor to excellent.
  
  
  CONCLUSIONS
  Availability of pharmacokinetic data for horses with gastrointestinal tract disease will facilitate appropriate clinical dosing of lidocaine.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Darien J
authors.initials: DJ
authors.lastname: Feary
authors.forename: Khursheed R
authors.initials: KR
authors.lastname: Mama
authors.forename: Sara M
authors.initials: SM
authors.lastname: Thomasy
authors.forename: Ann E
authors.initials: AE
authors.lastname: Wagner
authors.forename: R Mark
authors.initials: RM
authors.lastname: Enns
mesh_terms: D000758:Anesthesia / Q000662:veterinary*; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D000818:Animals; D005260:Female; D005767:Gastrointestinal Diseases / Q000378:metabolism / Q000662:veterinary*; D006734:Horse Diseases / Q000378:metabolism*; D006736:Horses; D007275:Injections, Intravenous; D008012:Lidocaine / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male; D014018:Tissue Distribution
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine