Treatment principles for the use of opioids in pain of nonmalignant origin.

Inadequately treated acute and chronic pain remains a major cause of suffering, in spite of enormous advances in pharmacology and technology. Opioids provide a powerful, versatile, widely available means of managing this pain, but their use is too often restrained by ignorance and mistaken fears of addiction. The management of postoperative pain (perhaps the most common form of acute pain) is traditionally attempted with fixed dosages of analgesics by relatively unpredictable routes (e.g. oral, rectal and intramuscular). Intravenous opioid infusions (an improvement) risk respiratory depression and require close monitoring and titration. Patient-controlled analgesia (PCA), by contrast, permits the most efficacious medication (pure opioid agonist) by the optimal route (intravenous) under direct control of the patient, and provides high levels of satisfaction and safety. Ideally, any opioid use should be integrated with a wide spectrum of other analgesic modalities in an anaesthesiology-based 'acute pain service'. The use of opioids for chronic pain of nonmalignant origin remains controversial. There is a perceived conflict between patients' interests and those of society. However, problems (such as tolerance, physical dependence, addiction and chronic toxicity), anticipated from experience with animal experiments and pain-free abusers, seldom cause difficulties when opioids are used appropriately to treat pain (so-called 'dual pharmacology'). With sensible guidelines, and in the context of a multidisciplinary pain clinic, opioids may provide the only hope of relief to many sufferers of chronic pain.