Medetomidine

From Dog

Medetomidine and dexmedetomidine are mainly used in dogs to facilitate short, noninvasive procedures or as part of a preanesthetic protocol prior to induction of general anesthesia with halothane, isoflurane or sevoflurane[1].

This drug is an α2-adrenergic receptor agonist, often used in combination with acepromazine and buprenorphine[2].

It is a racemic mixture of 2 optical enantiomers, levomedetomidine and dexmedetomidine, the latter being the biologically active molecule that is responsible for inducing all of the relevant alpha2 receptor-mediated effects[3].

This drug has similar properties to xylazine, but has a 10-fold greater selectivity for α2 selectivity[4] and is recommended in most clinical situations. This makes medetomidine potentially superior for use in small animals, particularly because of its antiarrhythmic property, which is mediated by imidazoline receptors associated with vagal tone stimulation[5].

Side-effects include cardiorespiratory depression and marked diuresis[6][7].

The effects of this drug are rapidly reversed with atipamezole.

Recommended dose in dogs is 15 to 40 μg/kg body weight.

References

  1. Kuusela E et al (2000) Clinical effects and pharmacokinetics of medetomidine and its enantiomers in dogs. J Vet Pharmacol Ther 23:15–20
  2. Vainio O (1989) Introduction to the clinical pharmacology of medetomidine. Acta Vet Scand Suppl 85:85–88
  3. Virtanen R (1989) Pharmacological profiles of medetomidine and its antagonist, atipamezole. Acta Vet Scand Suppl 85:29–37
  4. Virtanen R (1989) Pharmacological profiles of medetomidine and its antagonist, atipamezole. Acta Vet Scand Suppl 85:29–37
  5. Murrell JC & Hellebrekers LJ (2005) Medetomidine and dexmedetomidine: A review of cardiovascular effects and antinociceptive properties in the dog. Vet Anaesth Analg 32:117–127
  6. Talukder MH & Hikasa Y (2009) Diuretic effects of medetomidine compared with xylazine in healthy dogs. Can J Vet Res 73(3):224-236
  7. Burton S et al (1998) Effects of medetomidine on serum osmolality; urine volume, osmolality and pH; free water clearance; and fractional clearance of sodium, chloride, potassium, and glucose in dogs. Am J Vet Res 59:756–761