Opioid therapy for chronic noncancer pain: practice guidelines for initiation and maintenance of therapy.

Contemporary standard pharmacological care for the treatment of noncancer pain includes the use of opioid medications. The responsiveness of neuropathic pain to opioids has long been an area of controversy. Evidence from multiple randomized controlled trials indicates that opioids can relieve pain in a variety of neuropathic pain syndromes. Opioids are typically reserved for moderate to severe pain that cannot be relieved by the nonsteroidal anti-inflammatory drugs (NSAIDs). Opioids are often used in combination with other adjuvants or other analgesic agents. The advantage of opioids is the lack of a ceiling effect of the pure mu opioid agonists. The disadvantages of these drugs are a series of mechanism-based opioids-related side effects (e.g., nausea, drowsiness, constipation) and the potential issue of their abuse and misuse. Each patient needs to undergo a comprehensive evaluation and receive education on the treatment. The physician must be well conversant with the differential diagnosis and definitions of physical dependence, tolerance, pseudotolerance, aberrant behaviors, addiction, and pseudoaddiction. No specific opioid drug is intrinsically ''better'' than the others. Opioid rotation refers to the switch from one opioid to another when the degree of analgesia obtained is limited by the persistence of adverse effects or the occurrence of clinically relevant tolerance. This approach is based on the observation that a patient's response varies from opioid to opioid. At present, after 1) appropriate selection of patients and 2) longitudinal patient care with routine assessment of degree of analgesia, functional daily activities, adverse events and aberrant behaviors is carried out, opioid therapy can be the safest and most effective treatment measure for quality of life improvement in the chronic pain patient.