Pre-anaesthetic administration of alpha2-adrenoceptor agonists

Patients undergoing surgical intervention suffer from a variety of apprehensions and anxieties. In addition, they often have pain and they may present with co-existing disease. A pre-anaesthetic administration of α2-adrenoceptor agonists may have beneficial effects in this setting. Desired effects of a pre-anaesthetic medication are anxiolysis, sedation, analgesia, amnesia and the reduction of autonomic reflexes. Clonidine is the most widely used α2-adrenoceptor agonist for premedication, offering many of these desired actions. In addition, clonidine can be administered orally because of the high degree of enteral resorption. Both clonidine and the more specific α2-adrenoceptor agonist dexmedetomidine have been demonstrated to reduce anaesthetic requirements. Apart from β-adrenoceptor blockers, α2-adrenoceptor agonists are the only drugs for perioperative administration that have been shown to improve outcome after surgery in high risk patients. Thus, α2-adrenoceptor agonists should be an important part of the drug armamentarium used for premedication.