Addiction: a pattern of compulsive drug use, characterized by continued craving for an opioid and the need to use the drug for an effect other than pain relief.
Agonist: a drug that binds to pain receptors to produce analgesia.
Analgesia: absence of pain in response to a stimulus that would normally cause pain.
Analgesic ceiling: a dose beyond which a further increase in dose does not produce more analgesia.
Breakthrough pain: pain that occurs before the next scheduled dose of an analgesic.
Coanalgesic: a drug that has a primary purpose other than pain relief, such as an antidepressant or anti-convulsant, that can also augment analgesia for some painful conditions. May also be referred to as an adjuvant analgesic.
Dependence: a universal physiological and pharmacological phenomenon that occurs following the regular use of opioids for more than two weeks.
Modulation: the activities of descending neurological pathways from the brain that inhibit the cells responsible for transmitting pain signals.
Mu agonist: a type of opioid drug; mu agonists include morphine and other opioid drugs that produce analgesia by binding to mu receptor sites in the nervous system.
Narcotic: a term previously used to refer to opioid drugs. The term "narcotic" is currently used to refer to a wide variety of substances of potential abuse.
Neuropathic pain: abnormal processing of sensory input by the peripheral or central nervous system.
Nociceptive pain: normal processing of stimuli that damage normal tissues; may be somatic pain caused by damage to bone, joint, skin, or connective tissues; or visceral pain, caused by painful stimulation of visceral organs, such as the gastrointestinal tract. [L. nocere to injure]
Nonopioid: refers to acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs).
Noxious stimulus: a stimulus that damages normal tissue.
Opioid: all naturally occurring and synthetic drugs with morphine-like activity.
Opioid dose sparing effect: the dose of opioid may be lowered when a nonopioid is used.
Opioid naive patients: individuals who have not previously received opioid drugs and now, due often to trauma or surgery, receive regular doses of opioids.
Pain perception: the process of recognizing and responding to pain.
Physical dependence: a phenomenon that occurs with patients who have been taking long-term opioids; abrupt discontinuation of the drug, or the administration of an antagonist drug, causes physical withdrawal symptoms.
Titrating to effect: the practice of continuing to increase the dose of an opioid until the patient obtains a desired level of pain relief or until adverse reactions are unmanageable and intolerable.
Tolerance: refers to the requirement for a larger dose of opioid analgesia to maintain the original analgesic effect.
Transduction: conversion of one form of energy to another.
Transmission: movement of pain impulses from the site of transduction to the brain.