Premedication Drugs Flashcards
(23 cards)
What are the 6 drug classes used as premedication?
- Phenothiazines
- Alpha-2 agonists
- Benzodiazepines
- Alfaxalone
- Anticholinergics
- Opioids
Give an example of phenothiazines
- Acepromazine (ACP)
What are the pharmacodynamics of phenothiazines?
- Antagonise dopamine pathways
- Sedation, anti-emetic, antiarrythmic, reduces total anaesthetic dose
What are the pharmacokinetics of phenothiazines?
- Metabolised by the liver
What are the contraindications of phenothiazines?
- Liver disease
- Epilepsy
- Shock, CV disease, anaemia and splenectomy
- Causes respiratory depression and hypothermia
- Increases gastro-oesophageal reflux
What is the term used when a phenothiazine is combined with an opioid?
- Neurolepanalgesia
Give 3 examples of alpha-2-agonists
- Dexmedetomidine
- Medetomidine
- Xylazine
What are the pharmacodynamics of alpha-2-agonists?
- Stimulate alpha-2-receptors
- Sedation, reduces total anesthetic dose, analgesia
What happens when opioids or benzodiazpines are combined with alpha-2-agonists?
- Synergistic sedative effect
- Allowing reduced doses of A-2-A
What are the contraindications of A-2-A?
- Causes premature ventricular contractions or bradycardia abnormalities
- Can lead to upper airway obstruction in brachycephalic felines
- Causes emesis, so avoid patients with oesophageal obstructions
What is used to reverse alpha-2-agonists?
- Atipamezole
- Alpha-2-antagonist
Give 2 examples of benzodiazepines?
- Diazepam
- Midazolam
What are pharmacodynamics of benzodiazepines?
- Depress the sub-cortical levels of the CNS by working on GABA receptors
- Anxiolytic, anticonvulsant, stimulates appetite, reduces total anaesthetic dose
What are the contraindications of benzodiazepines?
- Causes excitation
- Can be irritant
- Reacts with plastic syringes
How are benzodiazepines used for pre-med?
- In combination with an opioid
How are benzodiazepines reversed?
- Flumazenil to block drug
Give 2 differences between midazolam and diazepam?
- M is water soluble whereas D is insoluble
- M metabolised by the liver into inactive metabolites, so shorter acting and less risk of accumulation whereas D vice versa
Give 2 examples of anticholinergics
- Atropine
- Glycopyrronium
What are the pharmacodynamics of anticholinergics?
- Blocks the parasympathetic nervous system
What are the contraindications of anticholinergics?
- Causes tachycardia
What are anticholinergics used for?
- Brachycephalic breeds
- Enucleations involving traction on the eyeball
- Laryngeal surgery
What are 2 the differences between atropine and glycopyrrium?
- Atropine able to cross BBB whereas glycopyrrium limited
- Atropine causes dilated pupils whereas glycopyrrium has no effect on pupils
Give examples of opioids
- Morphine
- Methadone
- Pethidine
- Buprenorphine
- Fentanyl
- Butorphanol
