56 terms

Opioid Agonists & Antagonists

how does an opioid differ from an opiate
opioid is a generic term referring to all drugs with morphine-like actions

opiate is morphine, codeine, other semisynthetic derivatives of morphine from opium
what are the 3 main opioid receptor types
mu, delta, kappa
what are the pharmacological effects of mu receptors
side effects---euphoria, resp depression, inhibiton of GI motility

mu receptors cause most clinically relevant analgesia------mu 1 mediates supraspinal analgesia & mu 2 mediates spinal analgesia
what are the pharmacological effects of kappa receptors
mediates both spinal and supraspinal antinociception

poss sedation and dysphoria
what are the pharmacological effects of delta receptors
mediates mainly at spinal, but also supraspinal antinociception

poor analgesia
what is a full opioid agonist and what drugs does this include
affinity and activity at all clinically relevant opioid receptors

morphine, codiene, meperidine, oxymorphone, hydromorphone, fentanyl, methadone, carfentanil
what is a partial opioid agonist and what drugs does this include
affinity but only partial activity for some opioid receptors

buprenorphine, nalorphine, tramadol, levallorphan
what is a mixed agonist-antagonist and what drugs does this include
affinity for multiple opioid receptors but are agonist at some receptors and are antagonist or weak agonist at other receptors

butorphanol & pentazocine
what is an opioid antagonist and what drugs does this include
affinity for all opioid receptors but no activity

nalaxone, diprenorphine, naltrexone
what are the CNS pharmacological effects of opioids incl effect on temp, vomiting center, cough center (in particular morph)
CNS depression--dogs, monkeys, humans
CNS stimulation--cats, horses, ruminants, pigs
hypothermia--dogs, rabbits, monkeys; hyperthermia--cats, swine, ruminants, horses
small dose, puke; large dose, no puke; no puke--swine, chickens, horses, rabbits, rum
inhibits cough center, but addictive, so no
what are the pharmacological effects of opioids on the eye (morph)
miosis in sp that become sedate (dogs, humans...b/c occulomotor n stimulation)
pupil dilation in sp that become excited (cats, sheep, horses, monkeys)
what are the pharmacological effects of opioids on the resp syst (morph)
initial stimulation of resp in dogs at sm doses (dissipate heat); decreases after time (and large dose).....mu2 activation depresses brain resp centers
what are the pharmacological effects of opioids on the cardio syst (morph)
coronary vasoconstriciton in dogs (poss d.t. activation of alpha receptors); brady and vasodilation d.t. vagal stim.; cerebral vasodilation---increases ICP
what are the pharmacological effects of opioids on the GIT, urin syst, imm syst (morph)
GI: vomiting, followed by constipation (segmental m contraction & relaxation of longitudinal m)
URIN: mu ag decrease urine d.t. ADH stim; kappa ag inhibit ADH, so increased urine; detrusor inhibition
IMM: histamine release if IV; natural endorphans; inhibition of apoptosis during ischemia
what drugs have a ceiling effect and why is this important
butorphanol & buprenorphine.............cardio safter, but give less pain relief d.t. their ceiling effect
how do opioids cause vomiting
via the CRTZ
how do opioids inhibit cough
inhibit the cough center
how do opioids cause miosis
oculomotor nerve firing (increased parasympathetic)
how do opioids cause mydriasis
catecholamine release prevents miosis
why do opioids initially stimulate resp and then sometimes decrease resp after the initial stimulation
at 1st panting b/c trying to dissipate heat; mu2 activation depresses brain
how do opioids cause potential cardio depression
what causes constipation with opioids
how do opioids inhibit urination
where are opioids metabolized and excreted
what about the pharmacokinetics limits oral availability of opioids
what are uses of opioids
what are the adverse effects and contraindications of opioids
which opioids have short lived analgesia
which opioid has the longest lasting analgesia
which opioids are weaker analgesics
why is buprenorphine difficult to reverse
why are full agonists less effective after using butorphanol or buprenorphine
which opioids are used as emetics
which opioids are used as antitussives
which opioids are used as antidiarrheals
which opioids cause histamine release and what route of administration is more likely to cause histamine release
how are most opioids given
which opioids are most commonly given orally (to send home as analgesics or cough suppr)
which opioid agonists (full, partial, mixed) are more potent (greater receptor binding affinity) than morphine
which opioid has a spasmolytic effect on sm m
which opioid has a vagolytic effect rather than an increased vagal effect
what opioid is very lipid soluble and therefore is quick-acting and short-lasting
which drug is fentanyl combined with and sold as innovar vet (neuroleptoanalgesic)
what are the pharmacological effects of innovar vet
what are the therapeutic uses effects of innovar vet
what are the adverse effects of innovar vet
what breed is resistant to innovar vet but more sensitive to side effects
how can salivation and bradycardia be controlled when using innovar vet
what is a reported reversal agent for innovar vet
how long does it take the fentanyl patch to work in cats, dogs, horses
how long does the fentanyl patch work
what are some precautions with the fentanyl patch
which opioid may also inhibit serotonin and NE uptake
for which type of analgesia is butorphanol best
for which opioid should naloxone not be used
if an opioid is more potent, does that mean it provides better analgesia