Mechanism of action
- morphine is naturally derived opiods which acts as
central analgesic
- acts on mu,kappa and delta receptors located
predominantly in brain.morphine can show both effect i.e; first stimulant and
then depressant and its analgesic effect is due to mu receptor
- all three receptor are present at prejunctional
neuron and are GPCRs
- binding of opioids agonist leads to activation of
GPCR and reduces formation of cAMP,followed by blocking or suppression of Ca+2
& voltage gated N type channel(mainly kappa receptor) and opens K+
channels(mainly through mu and delta receptor). Therefore this results in
hyperpolarization and decreases intracellular Ca+2 concentration,
leading to decrement in release of neurotransmitters by cerebral,spinal and
myenteric neurons.
Reference: Tripathi K.D.,
“Essentials of Medical Pharmacology”, Jaypee brothers medical publishers,
Seventh edition, New Delhi, page no. 386,479.
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