L4: Premedication (Garcia-Pereira) Flashcards
neuroleptics are major sedatives
:)
analgesics include:
opioids
neuroleptoanalgesia includes:
sedatives and opioids
factors involved in drug selection
species age physical status (ASA) animal behavior and attitude procedure duration of procedure experience with drugs used!
name 3 anticholinergics
atropine sulfate
glycopyrrolate
scopolamine
Ach present in which receptors?
muscarinic
nicotinic
MOA of anticholinergics**
- inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells
- may see worsening of bradycardia right at the beginning as receptor is blocked, then competitive effect decreases bradycardic effect of parasympathetics so that sympathetic overrides –> tachycardia
- will see transition of bradycardia –> 2nd degree AV block –> tachycardia**
physiological effects of anticholinergics
- dec. vagal influence in HR
- dec. secretions; harder to clear airway
- bronchial dilation
- inc. anatomical and physiological dead space
- dec. GI motor and secretory activity
chars. of Atropine sulfate
- an anticholinergic
- tertiary amine molecule
- high lipid solubility; easily crosses BBB and placental barrier
- used in emergency situations to inc. HR
- doesn’t last as long as glycopyrolate
chars. of glycopyrolate
- an anticholinergic
- synthetic quaternary ammonium molecule
- low lipid solubility
- does NOT cross BBB, placenta
- no effects on CNS
- same peripheral effects as atropine
- lasts longer than atropine
major tranquilizers
Phenothiazines (acepromazine, chlorpromazine, levomepromazine)
Butyrophenones (droperidol, azaperone)
chars. of Acepromazine maleate
- Potent sedative and anxiolytic (inhibits anxiety)
- Anti-emetic
- Anti-arrhythmic properties
- dec. dose requirement of other drugs
- enhances analgesia of opioids
- Boxers sensitive (can cause severe hypotension/bradycardia)
- no reversal!
side effects of Acepromazine
- dec. BP and vasomotor reflex
- cardiac depression
- peripheral alpha2-adrenergic blockade
- relaxation of vascular smooth m.
- persistent or permanent penile paralysis
chars. of droperidol and azaperone
- similar effects as ace
- better sedatives than ace in PIGS
name 2 mu-agonist (full agonists) opioids
morphine fentanyl: can be used at CRI methadone hydromorphone -provide more analgesia than kappa agonists but have more side effects including resp. depression, vomiting, bradycardia, and decreased GI motility -side effects limit dose -morphine longer acting than fentanyl
name a partial agonist opioid
buprenorphine
- good for mild to moderate pain
- effect plateaus even with increasing dose
- long onset of action and long duration of action
- good oral availability in cats but not dogs
name a kappa agonist/mu antagonist opioid
butorphanol nalbuphine -good for mild to mod analgesia -short-acting -can be used to reverse side effects of u-agonists
name 2 opioid antagonists
naloxone
naltrexone
(reverse opioid effects)
T/F: humans more sensitive to opioids than animals
T
specific side effects of morphine
hypotension
urticaria (hives)
specific side effects of hydromorphone
feline hyperthermia (?)
rank duration of action of mu-agonist opioids
morphine, hydromorphine, methadone: 4-6hrs
fentanyl: 20-30min.
rank potency of mu-agonist opioids
fentantyl > hydromorphone > methadone > morphine
locations of GABA receptors
hypothalamus cerebellum midbrain hippocampus medulla spinal cord
chars. of benzodiazepines
- act on GABA receptors (agonist)
- cause anterograde amnesia
- include diazepam, midazolam, zolazepam
chars. of diazepam
- benzo
- anxiolytic
- muscle relaxant
- anticonvulsant effect
- rapidly crosses BBB and placental barrier
- minimal CV effects (de. BP and CO)
- propylene glycol (high lipid solubility)
chars. of midazolam
- water soluble (becomes lipid soluble at pH>4)
- can be given IM
- more potent but shorter acting than diazepam
- similar effects as diazepam
- crosses BBB/placenta
chars. of zolazepam
- most potent benzo
- available only in telazol
- anticonvulsant and m. relaxant
- least apt to cause CNS effects
- expensive
flumazenil
- competitive antagonist of benzodiazepine receptor (GABA antagonist)
- very weak agonist effect (no anxiety w/ reversal)
- reverses effects of benzos
alpha2-adrenergic agonists
- anxiolytic
- sedative and m. relaxant
- analgesia
- dec. ADH, insulin release
- causes hypertension followed by hypotension
- reflex bradycardia
- high CV tole
CV effects of alpha2-adrenergic agonists
- dec. HR (hypertension, dec. sympathetic tone –> vasodilation)
- dec. CO (dec. myocardial contractility, dec. HR)
- increased then dec. BP
graph slide 27
:)
name 4 alpha2-adrenergic agonists
xylazine
detomidine
romifidine
dexmedetomidine
chars. of xylazine
- an alpha2-adrenergic agonist
- less selective to alpha2 receptors
- causes more ataxia
- shorter duration
chars. of detomidine
- an alpha2-adrenergic agonist
- not very selective to alpha2 receptors
- causes profound sedation
- ataxia
- mainly used in LA
chars. of romifidine
- an alpha2-adrenergic agonist
- not very selective to alpha2 receptors
- good sedation
- less ataxia than other alpha2-adrenergic agonists
- mainly used in LA
chars. of dexmedetomidine
- an alpha2-adrenergic agonist
- most selective
- profound sedation
- may be used to intubate some dogs
- mostly used in SA
- never use with xylazine!
alpha2-adrenergic agonist REVERSALS
Non-selective: Tolazoline, Yohimbine (SC or IM)
Selective: Atipamizole (SC or IM)
(may be given IV to LA)
Guaifenesin
- central muscle relaxant
- used as adjuvant in LA induction
- smoothes induction and decreases injectable dose
- disrupts trans. at spinal cord and brain stem
- increases RR and dec. tidal volume
