Neuraxial Dexmedetomidine: Wonder Drug or Simply Harmful

Copyright © 2015, Iranian Society of Regional Anesthesia and Pain Medicine (ISRAPM). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited. In current anesthesia practice, neuraxial anesthesia is a major method among all anesthesia modalities. The most frequently performed neuraxial blocks are consecutively subarachnoid, epidural, and caudal blocks. Major indications are intraoperative anesthesia and analgesia, postoperative analgesia, analgesia for vaginal delivery, and management of chronic pain. For these purpose, local anesthetics (LA) are widely used alone or in combination with adjuvants. Adjuvants are mixed with LA to shorten the onset of action, increase the quality of block, increase the duration of anesthesia and analgesia, and to decrease the dose of LA. Benzodiazepines (e.g. midazolam), opioids (e.g. morphine, fentanyl, and sufentanil), α-adrenergic agonists (e.g. epinephrine or phenylephrine), ketamine, and α2-adrenergic receptor agonists (e.g. clonidine or dexmedetomidine [DEX]) are adjuvants of common use. Mechanisms of action are also different. Out of these, α2-adrenergic receptor agonists are relatively newer and their uses are increasing. DEX, a dextrorotatory S-enantiomer of medetomidine, is an α2-adrenergic receptor agonist with the chemical structure being (S)-4[1-(2, 3-dimethylphenyl) ethyl]-3H-Imidazole (Figure 1).