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Clinical effects and pharmacokinetics of medetomidine and its enantiomers in dogs
Author(s) -
Erja Kuusela,
Marja Raekallio,
Markku Anttila,
I Falck,
Sari Mölsä,
Outi Vainio
Publication year - 2000
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1046/j.1365-2885.2000.00245.x
Subject(s) - medetomidine , dexmedetomidine , pharmacokinetics , sedation , anesthesia , medicine , heart rate , placebo , beagle , analgesic , sedative , blood pressure , bolus (digestion) , pharmacology , surgery , alternative medicine , pathology
The clinical effects and pharmacokinetics of medetomidine (MED) and its enanti‐omers, dexmedetomidine (DEX) and levomedetomidine (LEVO) were compared in a group of six beagle dogs. The dogs received intravenously (i.v.) a bolus of MED (40 μg/kg), DEX (20 and 10 μg/kg), LEVO (20 and 10 μg/kg), and saline placebo in a blinded, randomized block study in six separate sessions. Sedation and analgesia were scored subjectively, and the dogs were monitored for heart rate, ECG lead II, direct blood pressure, respiratory rate, arterial blood gases, and rectal body temperature. Blood samples for drug analysis were taken. Peak sedative and analgesic effects were observed at mean (± SD) plasma levels of 18.5 ± 4.7 ng/mL for MED40, 14.0 ± 4.5 ng/mL for DEX20, and 5.5 ± 1.3 ng/mL for DEX10. The overall level of sedation and cardiorespiratory effects did not differ between MED40, DEX20 and DEX10 during the first hour, apparently due to a ceiling effect. However, the analgesic effect of DEX20 lasted longer than the effect of the corresponding dose of racemic medetomidine, suggesting greater potency for dexmedetomidine in dogs. Levomedetomidine had no effect on cardio‐vascular parameters and caused no apparent sedation or analgesia. The pharmacokinetics of dexmedetomidine and racemic medetomidine were similar, but clearance of levomedetomidine was more rapid (4.07 ± 0.69 L/h/kg for LEVO20 and 3.52 ± 1.03 for LEVO10) than of the other drugs (1.26 ± 0.44 L/h/kg for MED40, 1.24 ± 0.48 for DEX20, and 0.97 ± 0.33 for DEX10).