Mechanism of action of Clonidine in opioid withdrawal syndrome is

Ans. is 'c' i.e., Action on a2 presynaptic nerve ending Many of the symptoms of opioid withdrawl such as nausea, vomiting, cramps, sweating, tachycardia, and hypertension are a result of loss of opioid suppression of locus ceruleus system during abstinence syndrome. Clonidine is an a2 agonist that reduces adrenergic transmission from locus ceruleus.Clonidine acts on these a2 receptors and supress adrenergic activity in locus ceruleus. (Thus mimicking the action of opioids).In this way it alleviates mainly the autonomic symptoms of opioid withdrawl.Non autonomic symptoms of opioid withdrawl are not affected.