ABSTRACT
Nitrous oxide is a useful short-acting adjunct, which provides some analgesia in labor and is effective for procedural analgesia in adults and children in a wide variety of settings. Its adverse effects on vitamin B12, in particular with repeat exposure, require consideration and supplementation to avoid rare, but serious toxicity leading to bone marrow suppression and neuropathy. Antidepressants play no role as adjuvants in the treatment of acute pain, but have shown a preventive effect on the development of subsequent chronic pain states. Systemic administration of lidocaine is an effective treatment of acute neuropathic pain of peripheral and central origin; due to its anti-inflammatory effect it might also be a useful adjuvant for perioperative pain treatment with benefits for analgesia and outcome. The chapter discusses the current status of adjuvant drugs in the acute pain context, together with their clinical pharmacology.
