Sedation and premedication Flashcards
Name a phenothiazine used as a sedative …
Acepromazine
Name a NMDA antagonist…
Ketamine
What effects can phenothiazines have on the cardiovascular system?
Hypotension due to vasodilation, Syncope due to hypotension (high vagal tone) and bradycardia, Adrenaline reversal potentiating vasodilation, anti-arrhythmia, reduced PCVNA
What effects do Phenothiazines have on the respiratory system?
Decrease sensitivity to CO2, paired with a decrease in respiratory rate, potentiate the respiratory depressant effect of other drugs
How can Phenothiazines act as anti-emetics?
They inhibit dopamine activity in the CTZ
How can sedative drugs cause hypothermia?
Due to vasodilation and decreased activity in the thermoregulatory centre
Does ACP have analgesic effects?
No
What is the onset and offset of ACP?
Onset - 30 mins, Offset - 4-8 hrs
Name four receptors which are acted upon by Phenothiazines.
Dopamine, adrenergic (a1), cholinergic, histamine
Does ACP cause muscle relaxation in patients? What potential problems does this cause?
Yes, causes muscle relaxation around the pharynx (particularly problematic in brachycephalics)
Name three alpha-2 agonists commonly used in practice…
Medetomidine, xylazine, romifidine, detomidine
Do alpha-2 agonists have analgesic effects?
Yes
How are a2As dealt with in the body?
Metabolised in the Liver and excreted in the urine.
What cardiovascular effects are observed with a2A administration?
Initial arterial hypertension with resulting peripheral vasoconstriction. Reflex bradycardia occurs(vagal and sympatholytic). Eventually BP is reduced to just below normal.
How do a2As cause diuresis?
Decreased ADH secretion, reduced renin secretion (RAAS), aids urethral relaxation
What respiratory effects can a2As have on patients?
Reduced RR, increased TV. Overall minute ventilation does not change.
a2As act as muscle relaxants. What effect can this have in the body?
Increased risk of gastro-oesophageal reflux (reduced LOS tone). Mydriasis and reduced aqueous tumour production.
Atipamezole can act as a reversal for which class of sedatives? What side effects may occur?
a2As - tachycardia, muscle tremors, over alertness, panting, vomiting.
Which Benzodiazepines are liscenced for use in veterinary practice?
None though diazepam and midazolam are commonly used
What is the mechanism of action of Benzodiazepines?
They act upon bdz receptors associated with GABAa receptors. They increase GABA affinity of these receptors (in inhibitory neurotransmitter)
Does Ketamine act as a muscle relaxant?
No, it increases muscle tone.
Does Ketamine have analgesic effects?
Yes
