Evaluation of the muscular relaxant effect of dexmedetomidine or medetomidine in cats

Abstract

The alpha2 adrenoceptor agonist medetomidine (MED) is an equal racemic mixture of two enantiomers, dexmedetomidine (DEX) and levomedetomidine (LEV); the LEV enantiomer is generally considered to be pharmacologically inactive, whereas the DEX enantiomer is active (Virtanen et al., 1988; MacDonald et al., 1991; Savola et al., 1991). Clinical studies in dogs and cats have shown that the pharmacodynamic effects of DEX are twice as potent as MED racemic mixture, therefore DEX administered at half the dose compared with MED for sedation; such as MED, DEX sedative and analgesic effects are antagonised by atipamezole (Cullen et al., 1996; Ansah et al., 1998; Kuusela et al., 2000; Ansah et al., 2000; Mendes et al., 2003; Granholm et al., 2006). DEX has been approved in Italy for clinical use in dogs and cats since 2008, and immediately we started to use it for dog and cat sedation. The DEX sedation effect in the dog is looked like MED, whereas the muscular relaxant effect in the cat was lower than MED. The aim of this study was to evaluate and compare the muscular relaxant effects in cats following DEX or MED used at bioequivalent dose

A comparison of medetomidine and its active enantiomer dexmedetomidine when administered with ketamine in mice

“…However, no significant difference was observed when levomedetomidine was co-administered with dexmedetomidine until levomedetomidine exceeded eight times the normal racemic preparation [13]. Although some studies have suggested that dexmedetomidine is superior to medetomidine [13,16], this may not be the case.…”

“…A handful of studies have compared the sedative effects of medetomidine and dexmedetomidine in the mouse and rat [3], dog [13,17,18], cat [16,19,20], and sheep [10]. All of these studies except two concluded there were no clinical advantages of dexmedetomidine over medetomidine [13,16].…”

“…All of these studies except two concluded there were no clinical advantages of dexmedetomidine over medetomidine [13,16]. Although there were no significant differences, one study concluded that “dexmedetomidine tended to be slightly more potent than the equivalent dose of medetomidine” and may provide more predictable sedation and analgesia in the dog [13].…”

“…Although there were no significant differences, one study concluded that “dexmedetomidine tended to be slightly more potent than the equivalent dose of medetomidine” and may provide more predictable sedation and analgesia in the dog [13]. A more recent comparison reported significantly greater muscle relaxation in medetomidine-treated cats [16]. …”

Anestesia epidural com associação medetomidina e lidocaína, em gatos pré-medicados com acepromazina e midazolam

“…O grau de relaxamento muscular central produzido pela medetomidina, dexmedetomidina e xilazina é considerado de boa qualidade (Vainio et al, 1989;Ansah et al, 1998) e está relacionado à inibição da transmissão intraneuronal dos impulsos no sistema nervoso central (Gross, 2003), sendo encontrado, também, por Scrollavezza et al (2009) …”