The Veterinary Record, Vol 138, Issue 5, 111-112
Copyright © 1996 by British Veterinary Association

Pharmacokinetics of lignocaine in Icelandic horses after infiltration anaesthesia

¹ Department of Pharmacology, University of Iceland, PO Box 8216, 128 Reykjavik, Iceland
² Watson's Veterinary Hospital, Vididal, 110 Reykjavik, Iceland

The pharmacokinetics of lignocaine was studied in four Icelandic horses after infiltration anaesthesia. A total of 240 mg of the drug was injected on either side of the left foreleg, over the medial and lateral branches of the palmar nerve. Blood samples were collected up to seven hours after injection and the concentrations of the drug in plasma were determined by gas chromatography/mass spectrometry. The results showed that lignocaine was rapidly absorbed. A mean maximum concentration of 232 ng/ml was observed after 20 minutes. In three of the horses the decline in the plasma concentration of the drug with time was best described by the sum of two exponential terms, but in one of the horses the decline was monoexponential. The mean half-life of the distribution phase () was 9·8 minutes and that of the elimination phase () 48·4 minutes. In all the horses the plasma concentration was below the limit of detection (2 ng/ml) six hours after injection. Anaesthesia was tested in one horse and lasted for one hour.