Anesthetic Drugs Flashcards
Pre-Anesthetic Medications
Phenothiazines, butyrophenones, a2-agonists
- sedation and anxiolytic
- anesthetic sparing
Opioids, A2-agonists, ketamine
- analgesia
Phenothiazines
MOA = anti-dopaminergic
Sedation Hypotension hypothermia anti-emetic anti-arrhythmic antihistaminic
NO ANALGESIA
Acepromazine
Premed
Phenothiazine
Calming effect
Mild sedation -> often combined w/ hydro or butorphanol
Slow onset
Butyrophenones
Premed
Less predictable than phenothiazines and tend to cause excitement before sedation
Less cardiorespiratory depression and less hyperthermia
Azaperone
Fluanisone
Benzodiazepines
Premed Anticonvulsant M relaxant Unreliable sedation and anxiolytic No analgesia
Has minimal CVS and resp effects
Diazepam
Premed
Benzodiazepine
Do not use for C-sections unless antagonist is available
Midazolam
Premed
Benzodiazepine
Reliable sedation for exotics
Flumazenil
Benzodiazepine antagonist on GABA receptor
Increases m tone to normal and improves ventilation
A2 Receptor Actions
Anxiolysis and sedation Anesthetic sparing CNS depression Anticonvulsant Neuroprotectant Analgesia M relaxation
Side Effects
- peripheral vasoconstriction = reflex bradycardia due to baroreceptor reflex
- reduced CO
- RR reduced
Atipamezole
A2 Antagonist
Reverses both sedation and analgesia
Only use IM
Side effects
- panting, m tremors, tachycardia, transient hypotension, vomiting, defecation
Trazodone
Behaviour Modifier
Reduce stress/anxiety
Gabapentin
Behaviour Modifier
Routinely used for tx of chronic pain and epilepsy
Propofol
Injectable Anesthetic
Acts on GABA receptors in CNS = anesthesia
short duration bc of extra-hepatic sites of metabolism = little accumulation/hang over effect
Side Effects
- CVS: myocardial depression, venodilation, hypotension, but no baroreceptor reflex
- Resp: post induction apnea and mild bronchodilation
Onset 40-90s
DOA 5-10 mins
Alfaxalone
Injectable Anesthetic
GABA receptors in CNS
Short DOA, rapidly metabolized, no accumulation
Side Effects
- hypotension w/ compensation via reflex tachycardia
- post induction apnea
Unclear analgesic properties
Onset 15-45 sec
DOA 5-10 mins
Ketamine
Injectable dissociative anesthetic
Interrupts info reaching the higher centers of the brain
Pair w/ m relaxant (benzodiazepine, a2) bc of m rigidity
CN reflexes are maintained –> central eye in dog, gag, swallow and palpebral reflexes
Onset 30-90 seconds
DOA 10-20 mins
Good analgesic –> esp for windup pain
Metabolism to norketamine excreted in urine
Side Effects
- sympathomimetic = increase HR and BP
- minimal resp depression -> can see apneustic breathing
Guaifenesin - GGE/Glycerol Guaicolate
Injectable Anesthetic
Large animal anesthesia for mild sedation
provides skeletal m relaxation
NOT AN ANESTHETIC or an analgesic –> rarely used alone
Usually w/ ketamine and xylazine
Isoflurane
IH Anesthetic
- rapid uptake and elimination
Very little hepatic metabolism
MAC
- 1.2% dog
- 1.3% cat
Sevoflurane
IH Anesthetic
- rapid uptake and elimination
3x as expensive as Iso
5% metabolized by liver and can produce Fl ions that are nephrotoxic
- but lungs eliminate drug so fast that not clinically a problem
MAC
- 2.4% dog
- 3.0% cat
Nitrous Oxide
Inhalant
Clinically used to supplement inhalant at 60%inhaled
Doxapram
Respiratory Stimulant
Directly stims the CNS and resp center –> to increase tidal volume and resp rate
Increases cerebral and myocardial O2 demand -> can be detrimental if patient isn’t breathing or hypoxemic
Ephedrine
Tx vasodilation
Mainly acts on adrenal gland to release endogenous NE
Anticholinergics
Tx bradycardia
Acts on muscarinic/cholinergic sites => works more on parasympathetic system
Prevents increases in vagal tone and excessive secretions
Atropine
Anticholinergic
DOA 30-40 mins
Onset 1-2 mins
Atropine can increase HR higher than glycopyrrolate
Glycopyrrolate
Anticholinergic
DOA 2 hrs
Onset 15-20 mins
