The haemodynamic and pharmacologic interaction of medetomidine and peripheral antagonist MK-467 and their dose-dependency in dogs

Johanna Kaartinen

Tutkimustuotos: OpinnäyteVäitöskirja

Abstrakti

The alpha-2 agonist, medetomidine (MED), and its pure active enantiomer dexmedetomidine (DMED), are in clinical use for small animal practice as potent sedatives, analgesic agents, muscle relaxants, and as an adjunct agents for balanced anaesthesia. However, their cardiovascular effects limit their use. The use of constant rate infusion (CRI) for administration of MED was studied in order to provide the sedation and analgesia while decreasing the cardiovascular adverse effects. The second avenue of investigation performed was addition of the peripheral alpha-2 antagonist, MK-467, to limit the haemodynamic effects of MED. The cardiovascular effects of MED CRI were investigated in a dose finding study. Six dose levels were administered during general anaesthesia from very low dose until a high, positive control dose in order to quantify dose-dependency. In order to elucidate an appropriate agonist-antagonist dose ratio a step-down infusion protocol of MED and addition of step-up infusion protocol of MK-467 in anaesthetised dogs was performed. The effects and interaction of both drugs during absorption, and distribution phase were studied during an intramuscular study protocol using a co-administration of both drugs, where three doses of MK-467 were investigated. Plasma concentration measurements provided pharmacokinetic parameter estimates. MED-CRI administration showed promising results, in demonstrating the dose-dependency of the cardiovascular effects. With the low doses of MED CRI, the adverse effects may be minimised, although not completely avoided. A complex pharmacokinetic and pharmacodynamic interaction in between the two molecules was revealed; after intramuscular (IM) co-administration of both drugs the absorption of MED was accelerated by the addition of MK-467 to the treatment. The step infusions revealed that MK-467 also increased the elimination of MED. The optimal dose ratio finding is complicated as the context in which the drugs are given (IM, IV, CRI, under general anaesthesia etc.) affects the disposition of MED. The combined pharmacokinetic and dynamic results provide good initial pharmacokinetic estimates for the future PK-PD modelling to predict the interaction of these two drugs, MED and MK-467, in dogs.Medetomidiini on alpha-2 agonisti, joka on hyvin yleisessä käytössä pieneläinlääkinnässä rauhoitusaineena. Medetomidiinin muita vaikutuksia ovat kivun lievitys, lihasrelaksaatio, sekä yleisanestesian aikana nukutusaineiden tarvetta vähentävä vaikutus, täten medetomidiini auttaa vähentämään nukutusaineiden haittavaikutuksia ja tasapainottaa yleisanestesian tasoa. Medetomidiinin sydän- ja verenkiertoelimistöön kohdistuvat haittavaikutukset ovat rajoittaneet käyttöä vain terveiden eläinten rauhoitukseen.
Alkuperäiskielienglanti
Myöntävä instituutio
  • Helsingin yliopisto
Valvoja/neuvonantaja
  • Vainio, Outi, Valvoja
  • Raekallio, Marja, Valvoja
  • Troncy, Eric, Valvoja, Ulkoinen henkilö
Myöntöpäivämäärä28 lokakuuta 2016
JulkaisupaikkaHelsinki
Kustantaja
Painoksen ISBN978-951-51-2459-3
Sähköinen ISBN978-951-51-2460-9
TilaJulkaistu - 28 lokakuuta 2016
OKM-julkaisutyyppiG5 Tohtorinväitöskirja (artikkeli)

Tieteenalat

  • 413 Eläinlääketiede

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