Prolongation of epidural anaesthesia in dogs with bupivacaine in a lipid emulsion.
An aqueous solution and a lipid emulsion of bupivacaine were administered epidurally in doses of 1.8 mg/kg to six beagle dogs following a randomised two-phase crossover design. The aqueous solution was absorbed rapidly and the mean (sd) peak venous plasma concentration of bupivacaine, 1.4 (0.4) microg/ml, was detected after five minutes. After administration of the lipid emulsion, the peak plasma concentration of bupivacaine, 0.6 (0.2) microg/ml, was detected after 30 minutes. The mean (sd) t1/2beta of the aqueous preparation was 149.1 (32.6) minutes, and of the lipid emulsion 119.2 (34.0) minutes. Both preparations had a similar bioavailability. The mean time to the onset of motor block after the administration of the aqueous solution, 2.3 (2.2) minutes, was significantly shorter (P=0.028) than after the administration of the lipid emulsion, 9.4 (1.9) minutes, and the duration of the motor block induced by the lipid emulsion, 217.6 (26.2) minutes, was significantly longer (P=0.043) than for the aqueous solution, 158 (48.8) minutes. During anaesthesia, the plasma concentrations of bupivacaine ranged between 1.3 and 0.2 microg/ml. Non-significant changes in systolic blood pressure and heart rate were observed which coincided with the peak plasma concentrations of bupivacaine.
Franquelo
C
C
Divisiò de Farmacologia, Facultat de Veterinària, UAB, Bellaterra, Spain.
Toledo
A
A
Manubens
J
J
Cristòfol
C
C
Valladares
J E
JE
Arboix
M
M
D000767:Anesthesia, Epidural / Q000662:veterinary*; D018686:Anesthetics, Intravenous / Q000493:pharmacokinetics; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000493:pharmacokinetics; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D002626:Chemistry, Pharmaceutical; D018592:Cross-Over Studies; D004285:Dogs / Q000378:metabolism / Q000502:physiology*; D004357:Drug Synergism; D004655:Emulsions; D008297:Male; D015742:Propofol / Q000493:pharmacokinetics
D018686:Anesthetics, Intravenous; D000779:Anesthetics, Local; D004655:Emulsions; D002045:Bupivacaine; D015742:Propofol