opioid

(noun)

Any of a class of psychoactive chemicals that works by binding to opioid receptors in the nervous system; among the world's oldest known drugs, the analgesic effects of opioids are due to decreased perception of pain, decreased reaction to pain, and increased pain tolerance.

Related Terms

Examples of opioid in the following topics:

  • Analgesia: Relief from Pain

    • This reduces pain and also inflammation (in contrast to paracetamol and the opioids).
    • Morphine, the archetypal opioid, and various other substances (e.g. codeine, oxycodone, hydrocodone, dihydromorphine, and pethidine) all exert a similar influence on the cerebral opioid receptor system.
    • Dosing of all opioids may be limited by opioid toxicity (confusion, respiratory depression, myoclonic jerks, and pinpoint pupils) and seizures (tramadol), but there is no dose ceiling in patients who accumulate tolerance.
    • Opioids, while very effective analgesics, may have some unpleasant side-effects.
    • Pruritus (itching) may require switching to a different opioid.

  • Depressants

    • An opioid is any psychoactive chemical that resembles morphine or other opiates in its pharmacological effects.
    • Known for their highly addictive quality, opioids work by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract.
    • Opioids are among the world's oldest known drugs; therapeutic use of the opium poppy predates recorded history. 
    • As opposed to these naturally occurring opioids that are derived directly from the resin of the poppy plant, synthetic opioids are synthesized chemically in the laboratory and are agents commonly used in pain relief, treating drug dependence and anesthesia.
    • In the United States, it has since become associated with opioids, commonly morphine and heroin and their derivatives.

  • Epidural Anesthesia

    • It can be used as an addition to general anesthesia, reducing the patient's need for opioid analgesics.

  • Adrenal Medulla

    • All of these peptides bind to opioid receptors and produce analgesic (and other) responses.

  • Narcotics

    • Because the term is often used broadly, inaccurately or pejoratively outside medical contexts, most medical professionals prefer the more precise term opioid.
    • Narcotics bind to painkilling sites throughout the brain, known as opioid-u receptors, or the "reward pathway. " This leads to slower uptake of neurotransmitters such as dopamine between neurons.
    • The withdrawal symptoms experienced from opioid addiction are usually first felt shortly before the time of the next scheduled dose.

  • Renal Calculi

    • For symptomatic stones, pain control is usually the first measure, using medications such as non-steroidal anti-inflammatory drugs or opioids.

  • Type I (Anaphylactic) Reactions

    • Agents that can damage these cells include contrast medium for X-rays, opioids, temperature (hot or cold), and vibration.

  • Plant Defenses Against Herbivores

    • Other alkaloids affect herbivores by causing either excessive stimulation (caffeine is one example) or the lethargy associated with opioids.

  • The Anterior Pituitary

    • Beta-endorphin is a polypeptide that effects the opioid receptor, whose effects include the inhibition of the perception of pain.

  • Types of Neurotransmitters by Function

    • Addictive drugs such as cocaine and amphetamine exert their effects primarily on the dopamine system, while addictive opiates and functional analogs of opioid peptides which regulate dopamine levels.