Additives used to reduce perioperative opioid consumption 1: Alpha2-agonists.

Because of their significant side effects, especially in obese patients, the routine perioperative use of opioids has been questioned recently. Alpha2-agonists are drugs with a considerable analgesic potency with the potential to reduce opioid consumption. Alpha2-agonists bind to alpha2-adrenergic receptors in the CNS and peripherally. They inhibit the central sympathetic outflow, resulting in an attenuation of blood pressure and heart rate and in a sparing effect on anaesthetics and analgesics. In the postoperative period alpha2-agonists provide an analgesic effect without respiratory depression and other known opioid side effects. Intraoperatively, a complete replacement of the synthetic opioid fentanyl by the alpha2-agonist dexmedetomidine has been demonstrated. Although alpha2-agonists have a sedative action, recovery times are not prolonged compared to those of opioids. Cardiovascular side effects such as bradycardia and hypotension have to be observed and treated.