Opioid analgesia

Question	Answer
K (KOPr)	Therapeutic effect: Analgesia Abuse: Dysphoria/hallucinations Side effects: Diuresis
d (DOPr)	Therapeutic effect: Analgesia Side effect: Antidepressant + proconvulsant
M (MOPr)	Therapeutic effect: Analgesia Abuse: Euphoria (due to inhibition of gabaergic inhibitory interneuron) Side effect: Respiratory depression + constipation
Analgesia	+ of GIRK -> -ve inside cell, - pain info (-) voltage gated ca2+ channels
Physical dependence	(-) AC
Which G proteins are opiod receptors coupled to?	Gi/Go beta-gamma/ alpha subunits mediate the effects of analgesia and physical dependence
Physical dependence	Withdrawal syndrome of physical signs and symptoms
Psychological dependence	Compulsive drug seeking behavior
Euphoria and drowsiness	Disinhibition in the VTA --> increased DA in the Nucleus Accumbens
Respiratory depression	Decreased brain sensitivity to PaCO2
Nausea	+ of CTZ in brain stem
Miosis	+ CN3 PSNS
Morphine	M agonist
Heroin	M agonist 3 ester groups, easily x BBB but has decreased receptor binding
Codeine	MeO group -> decreases effectiveness
Pentacozine	M/K agonist
Tramadol	Weak M agonist
Naloxone	M, d, K opioid antagonist
Carbamazepine	anti-epileptic Severe pain
Gabapentine	Anti-epileptic Severe pain
Amytryptyline	Antidepressant Severe pain
Problems with opioids as analgesics	Side effects Break through pain Neuropathic pains
Therapeutic uses of opioids	Pain relief Severe diarrhoea Cough suppression
Consequences of MR +	inhibition of neuronal firing (increased potassium conductance) Decreased transmitter release (inhibition of Voltage gated Ca2+ ch) Dis inhibition
Sites of action	Peripheral sensory nerves Spinal cord (dorsal horn) Supra spinal sites (activation of descending inhibitory pathways)
Supraspinal sites of action	PAG RVM (Midline raphe nuclie)
Review	endogenous opioid peptides

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	Created by Bhavi Mistry over 11 years ago