Lecture 2 8/22/24 Flashcards
What are the reasons for providing pre-medication prior to induction?
-facilitate handling
-have a smooth induction
-decrease dose of induction and maintenance drugs
-reduce adverse effects of induction and maintenance drugs
-improve/provide preemptive analgesia
-decrease airway secretions
-improve quality of recovery
What is a tranquilizer?
drug that relieves anxiety without causing major sedation
What is a sedative?
drug that relieves tension and anxiety, allowing sleep
What is neurolept analgesia?
combination of neurolept and analgesic
What are the properties of neurolepts?
-inhibition of emesis
-inhibition of motor activity and arousal
What are the components of dissociative anesthesia?
-analgesia
-amnesia
-catalepsy (paralysis with motor and sensory failure)
What is balanced/multimodal anesthesia?
using drugs/methods that act through different mechanisms/receptors
What are the components of balanced anesthesia?
-sedation or unconsciousness
-muscle relaxation
-analgesia
-amnesia
Which drug classes are considered sedatives/tranquilizers?
-phenothiazines
-butyrophenones
-benzodiazepines
Which drug classes are considered analgesics?
-alpha-2 adrenoceptor agonists
-opioids
What are the characteristics of acepromazine?
-commonly used in healthy animals
-not a potent sedative
-decreases minimum alveolar concentration of volatile drugs
What is the receptor activity of acepromazine?
blocks dopamine receptors; dopamine has important role in motor activity
What are the physiological effects of acepromazine?
-mild tranquilizing effect
-decreases involuntary movements/reflexes
-anti-histaminic
-anti-emetic
-reduces risk of arrhythmias
-vasodilation
-hypothermia
-penile paralysis
-antipyretic
What are the clinical uses of acepromazine?
-tranquilization
-premedication prior to GA
-recovery from GA/smooth process
What are the characteristics of acepromazine for clinical use?
-mild muscle relaxation
-no analgesia
-slow onset
-sedation persists for several hours
-metabolized by liver
What are the considerations when dosing acepromazine?
-clinical doses are much lower than label doses
-higher doses do not increase depth of sedation
-higher doses DO prolong sedation and increase adverse effects
-no reversal agent
What is the most commonly used drug class in vet med?
alpha-2 adrenergic drugs
What are the characteristics of alpha-2 adrenergic drugs?
-dose dependent effects
-reliable sedation
-effective analgesia
-reversible
-effective in most species
-administered IM, IV, epidural, or transmucosal
What are the clinical uses of alpha-2 adrenergics?
-sedation
-analgesia
-premedication prior to GA
-recovery from GA
What are the physiological effects of alpha-2 agonists?
-decreased MAC of volatile anesthetics
-visceral and somatic analgesia
-initial hypertension combined with bradycardia
-later vasodilation and decreased contractility and cardiac output
-increased urine output
-decreased GI motility
-hyperglycemia
-uterine contraction in late pregnancy
-resp. depression
-decrease in surgical stress (good)
What are the advantages of alpha-2 agonists?
-small volume
-reversible
-compatible with most drugs
-analgesia
-dose-dependent sedation
-decreased MAC
-block stress response
-can induce emesis
What are the disadvantages of alpha-2 agonists?
-cardiovascular effects
-decreased GI motility
-emesis
-diuresis
-hyperglycemia
-respiratory adverse effects
What are the characteristics of alpha-2 adrenoceptor antagonists?
-reverse over-sedation or cardiovascular adverse effects
-less selective antagonists
-can lead to hypotension and tachycardia
What are the characteristics of atipamezole/antisedan?
-most selective antagonist
-primarily for dexmedetomidine
-can be used to reverse other alpha-2s
What are the adverse effects of alpha-2 antagonist overdose?
-neurological; excitement and tremors
-cardiovascular; hypotension and tachycardia
-GI; salivation and diarrhea
What is the preferred administration route for alpha-2 adrenoceptor antagonists?
IM
What are the characteristics of benzodiazepine function?
-GABA receptor agonists
-enhance binding between GABA and receptor to open chloride channels
-hyperpolarization inhibits cell function
What are the clinical effects of benzodiazepines?
-sedation/anxiolysis
-muscle relaxation
-anticonvulsant
-retrograde amnesia
-minimal CV and resp. side effects
In which animals do benzos have better effects?
debilitated or old dogs and cats
What are the characteristics of diazepam?
-water insoluble
-IM administration is irritating and has unpredictable absorption
-IV administration must be done slowly to avoid adverse effects
-sensitive to light
-adheres to plastic
-highly protein bound
-highly lipid soluble
What is diazepam used for?
-co-induction muscle relaxant
-neuroleptic anesthesia induction
-sedation/induction in debilitated and/or high risk animals
What is midazolam used for?
-sedative and muscle relaxant effects
-sedation in ruminants/pigs
What are the characteristics of midazolam?
-water soluble
-can be administered IM with no pain
-can be mixed with other drugs
-lipid soluble after injection
-light sensitive
-shorter duration of action compared to diazepam
What are the characteristics of zolazepam?
-only found in telazol
-mixed with tiletamine
-combination is used for premedication and as anesthetic
-longer duration of action
-longer recovery time
What is flumazenil?
benzodiazepine antagonist
What are the characteristics of flumazenil?
-binds to GABA receptor
-rarely needed clinically
-reverses benzo overdose
What is the role of anticholinergics?
block the action of Ach at muscarinic receptors
What are the clinical effects of anticholinergics?
-increase heart rate and enhance AV conduction
-bronchodilation
-decrease salivary and GI secretions
-decrease peristalsis
What are the characteristics of atropine sulfate?
-intense effect on heart rate
-first line of treatment for severe bradycardia
-shorter duration of action than glyco
-rabbits are resistant and need higher doses
-can be given IM, IV, SQ, IT
What are the possible adverse effects associated with atropine crossing the BBB?
-excitement/delirium
-blindness
-hyperthermia
-redness
-bladder distension and/or no urge to urinate
What are the characteristics of glycopyrrolate?
-no BBB crossing and therefore no CNS signs
-less intense cardiovascular effects
-less likelihood of arrhythmias compared to atropine
-longer acting than atropine
-longer onset of action compared to atropine
-given IM, IV, SQ
When is atropine used vs glyco?
Atropine: increasing heart rate quickly/in emergency situation
Glyco: increasing heart rate when bradycardia is not severe; premed. to decrease secretions
What are the contraindications for anticholinergic use?
-hypertension
-tachyarrhythmias
-congestive heart failure
-cardiovascular diseases that do not tolerate tachycardia
-glaucoma
-increased intraocular pressure
