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47 Cards in this Set
- Front
- Back
primary drug target of opioids
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mu receptor
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endogenous peptides with opioid activity are made from cleavage of what proteins
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Proopiomelanocortin POMC
proenkephalin prodynorphin |
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biologically active metabloits of pre opioid-like proteins
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metenkephalin
leu-enkephalin dynorphin A and B |
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mu receptors effector systems
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K channels (opened by agonist)
Ca channels (agonist reduce opening) adenylate cyclase (inhiibtion) |
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K channel activation plus Ca channel inhibition plus adenylate cAMP reduction cause
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reduced amount of transmitter release and therefore causes presynaptic inhibition
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K channel activation causes
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inhibition of the discharge rate of neurons
POSTSYNAPTIC INHIBITIONNNNNN |
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allodynia
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pain caused by previously inocuous stimuli, often associated with inflammation, like in gout
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algogen
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activators of peripheral nociceptors
bradykinin, histamine, serotonin |
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mechanism of opioid analgesia
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spinal mechanism:
dorsal horn contains opioid interneurons that gate nociceptive inputs by pre and postsynaptic inhibiton descending inhibition: pathways from the pons potentiate spinal analgesia by opiates (serotonin and noradrenalin) |
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which is relieved better by morphine, continuous dull pain or sharp intermittent
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continuous dull
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true/false: morphine decreases pain, touch, vibration and temperature sensations to equal degree
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false, pain is decreased much more than other sensory modalities
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morphine causes respiratory depression, particularly affecting the ______ or respiration
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rate
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mechanism of action of morphine that causes respiratory depression
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acts on brain stem respiratory centers and reduces responsiveness to pCO2
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main drive for respiration in a morphinized patient
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hypoxic stimulation of carotid chemoreceptors
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morphines effect on cough reflex and GI
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antitussive
produces nausea and vomiting |
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effects of morphine on neuronendocrine system
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hypothermia
decreased urinary output hyperglycemia decreased release of pituitary gonadotrophic hormones |
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morphine effect on pupils
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miosis (Edinger westphal nucleus)
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at extremely high doses, morphine may cause
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convulsions and seizures
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morphine effects on CV system
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peripheral vasodilation (decrease of sympathetic tone)
postural hypotension |
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morphine affect on GI
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acts on nerve plexi of GI
decreases propulsive peristaltic contractions increases tone and non propulsive rhthmic contractions |
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used to antagonize the spasmogenic actions of morphine and potentiate anti propulsive activity
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atropine
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morphine A, D, M, E
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readily absorbed from GI or nasal mucosa or lungs, injection availabe via skin, muscle, or venous routes
penetrates CNS poorly, compared to heroin does not accumulate in tissues and has short half life (4 hrs) conjugated with glucuronic acid in liver elimination depends on metabolism, excreted by urine 90%, 10% biliary |
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pinpoint pupils
depressed respiration BP fall low body temp flaccid skeletal muscle possible convulsion |
symptoms of acute morphine poisoning
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symptoms of acute morphine posioning
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pinpoint pupils
depressed respiration BP fall low body temp flaccid skeletal muscle possible convulsion |
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treatment of acute morphine poisoning
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ventilation
repeated injections of nalaxone (antagonist) |
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tolerance to morphine is
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pharmacodynamic
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withdrawel from morphine is better or worse than that from ethanol and barb
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leess severe
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slowly demethylated to morphone
absorbed better (affective orally and parenterally) |
codeine
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phenylpiperidine derivitive
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meperidine
diphenoxylate |
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in equianalgesic doses, less spasmogenic, less constipation, and less urine retention than morphine
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meperidine
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preferred opiate for obstetrical analgesia
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meperidine
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meperidine
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phyilpiperidine derivitive
hydrolized to meperidinic acid conjugated in liver to normeperine and exerts excitatory affects |
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used in the treatment of diarhea with atropine
virtually insoluble little abuse potential no perceptible CNS effects in theraputic range |
diphenoxylate
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80 times more potent than morphine
used in combo with droperidol |
fentanyl
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superior to morphone in most ways, oral abs, larger T1/2 (15 hrs), less withdrawel, ident pharm,
used for opiate addiction replacement therapy |
methadone
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prescribed in lieu of codeine
less effective |
propoxyphene
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depot opiate
produces methadone used in treatment of addiction |
1 acetylmethadol
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powerful kappa agonist
analgesic = morphine resp dep < morhphine dysphoria > morphine |
pentazocin
low abuse liability |
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antagonist of morphine
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naloxone
naltrexone |
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naloxone
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antagonist of opioids
zero bioavailablity orally IV short T1/2 |
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dextromethorphan
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no analgesic potency
antitussive very minimal toxicity |
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clonidine
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reduces the adversive quality of withdrawal from opiate
may reduce craving |
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criteria for opioid choice
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type of pain
required duration of action intensity of pain |
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long acting opioid
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methadone, morphine, oxymorphone
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short acting opioid
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meperidine
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used for low to moderate pain
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oral codeine
or low doses of oxcodon or hydrocodone + aspirin |
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used for intense pain
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NSAIDS morphine
oxymorphone iv or sc intrathecal opiates |