Opioids Flashcards
Opium
resinous extract from the capsule of poppy plant (Papaver somniferum)
Analgesic opioids
Phenanthrene derivatives
morphine
codeine
Non analgesic opioids
Benzoisoquino derivatives
Noscarpine (cough suppressant)
Papaverine (phosphodiesterase inhibitor)
opioid receptors and effects
Mu - endomorphic or endorphins
Kappa - Dynorphin
Delta - Enkephalins
4th receptor - ORPHAnin/ FQ receptor - Nociceptin
Mu receptor effects
sedation
analgesia (spinal, supra spinal)
constipation, cough suppression
respiratory depression
euphoria
miosis - pin point pupil
nausea/vomiting
gall stones (biliary colic)
abdominal colic (spasm of sphincters)
prolactin release
SACRUM No GAP
kappa receptor effects
all effects are like mu receptors except no euphoria
Dysphoria: psychotic symptoms
delta receptor effects
analgesia - mainly supraspinal > spinal (reduces pain perception- emotional/affective)
convulsions
constipation
respiratory depression
morphine
analgesic
MI - vagomimetic & reduces chest pain, apprehension, symptoms outflow
acute LVF/pulm edema- ventilator
routes- oral, iv, I’m, epidural, spinal, transdermal, except intrathecal (risk of hypotension as it suppresses VMC
except intranasal and sublingual
morphine undergoes glucuronide conjugation to form morphine-6-glucuronide and morphine-3-glucuronide (minor form; toxic-convulsions in children)
morphine-basic drug-histamine release from mast cells - SE: asthma, pruritis
oral/iv morphine - produces miosis
eye drops morphine - does not produce miosis
Opioids contraindicated in renal failure
Pethidine
Codeine
Morphine
Least potent opioid
Codeine (methyl morphine) - 1/10th analgesic
equally antitussive (suppresses cough centre)
codeine is metabolised by CYP2D6 into morphine
10x more potent analgesic and more addictive
Heroin (Diacetyl morphine) / brown sugar/ smack
100x more potent than morphine
fentanyl
1000x more potent than morphine
max plasma protein bound
Sulfentanyl
mu agonist plus snri
Tramadol
Tapentadol
Antitussives
Codeine
Hydrocodone
Oxycodone
Pholcodeine
Morphine
Hydromorphone
Oxymorphone
Levorphanol
SE: addiction, sedation
non addictive
Dextromethorphan- NMDA Antagonist
Noscarpine: Sigma agonist
Pethidine/Merperdine
mu agonist + anticholinergic
DOC for pregnancy and post anesthesia shivering
prodrug: pethidine converted into merperdine (active) and norpethidine (minor) - SE: seizures
CI: MAO inhibitors/ in renal failure
atropine like effects : increases heart rate - CI: MI
antispasmodic: least risk of colicky pain
opioids with least risk of causing coliky pain
Pethidine
Fentanyl
highly LS drug - best analgesic
all routes except oral - high FPM in liver
transdermall- chronic cancer pain
epidural injection- epidural analgesics
iv inj, SL, buccal - acute pain
rare SE: wooden chest syndrome- muscle rigidity
Remifentanyl
shortest opioid - rapidly metabolised by plasma esterase
iv drug
DOC for day care surgery and total iv anesthesia (add to Propofol)
Day care surgery
General anesthetic: Propofol
Analgesic: Remifentanyl
Skeletal muscle relaxants: Mivacurium
Longest opioid
Methadone
mu agonist and NMDA antagonist
iv action starts in 10-20 mins
oral action starts in 30-40 min
use - opioid deaddiction (no kick, prevents withdrawal)
SE: increase QT interval
partial Kappa agonist and mu antagonist
Pentazocine: reduces risk of colicky pain- renal colic
Nalorphine
Butarphanol- migraine headaches
ADV: less risk of respiratory depression
SE: dysphoria
CI: opioid deaddiction
pure Kappa agonist
Nalfurafine- uremic pruritus in CKD
Asimadoline and Eluxadoline - diarrhoea in IBS
SE: dysphoria/psychosis
partial mu agonist and Kappa antagonist
Buprenorphine - opioid deaddiction, less risk of respiratory depression as compared to Methadone, effect cannot be reversed by Naloxone
Dezocine - iv analgesic, less risk of respiratory depression
