indication

For sedation of initially intubated and mechanically ventilated patients during treatment in an intensive care setting, also used in pain relief; anxiety reduction and analgesia

pharmacology

Dexmedetomidine activates 2-adrenoceptors, and causes the decrease of sympathetic tone, with attenuation of the neuroendocrine and hemodynamic responses to anesthesia and surgery; it reduces anesthetic and opioid requirements; and causes sedation and analgesia.

mechanism of action

Dexmedetomidine is a specific and selective alpha-2 adrenoceptor agonist. By binding to the presynaptic alpha-2 adrenoceptors, it inhibits the release if norepinephrine, therefore, terminate the propagation of pain signals. Activation of the postsynaptic alpha-2 adrenoceptors inhibits the sympathetic activity decreases blood pressure and heart rate.

biotransformation

Hepatic

half life

2 hours

route of elimination

A mass balance study demonstrated that after nine days an average of 95% of the radioactivity, following intravenous administration of radiolabeled dexmedetomidine, was recovered in the urine and 4% in the feces. Fractionation of the radioactivity excreted in urine demonstrated that products of N-glucuronidation accounted for approximately 34% of the cumulative urinary excretion. The majority of metabolites are excreted in the urine.

drug interactions

Tranylcypromine: Tranylcypromine, a strong CYP2A6 inhibitor, may decrease the metabolism and clearance of Dexmedetomidine.

Treprostinil: Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.

Trimipramine: Trimipramine may reduce the antihypertensive effect of the alpha2-agonist, Dexmedetomidine. Trimipramine may also increase the rebound hypertensive effect of Clonidine. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of Clonidine if Trimipramine is initiated, discontinued or dose changed. Dexmedetomidine should be withdrawn very gradually to reduce the risk of hypertensive crisis.