Opioids are a class of drugs that are commonly prescribed for their analgesic, or pain-killing, properties. They include substances such as morphine, codeine, oxycodone, and methadone. Opioids may be more easily recognized by drug names such as Kadian, Avinza, OxyContin, Percodan, Darvon, Demerol, Vicodin, Percocet, and Lomotil.
Opioids may be classified as natural, semi-synthetic, fully synthetic, or endogenous. Natural opioids such as codeine and morphine are derived from opiate alkaloids contained in the resin of the opium poppy. Semi-synthetic opioids such as oxycodone and hydrocodone are created by chemically altering the natural opioids. Fully synthetic opioids such as methadone are synthesized from non-opioid substances in laboratories. Endogenous opioids are naturally produced by the body and include substances such as endorphins.
Opioids bind to specific proteins called opioid receptors that are located in the brain, spinal cord, and gastrointestinal tract. Through this mechanism, opioids are able to block the brain's ability to perceive pain. Instead, opioids tend to stimulate the pleasure centers of the brain, inducing euphoria.
Opioids are used in medicine because they can block the perception of pain. Patients receiving palliative care frequently report pain as one of the most distressing factors as they approach the end of life. About 70% of patients with advanced cancer and 65% of patients dying from other non-malignant diseases commonly complain of pain 1. Opioid-based medicines are prescribed to these patients to reduce their pain and increase their quality of life. The vast majority of patients receiving long-term opioid pain medication are in advanced stages of their disease.
Opioid use carries several side effects. These include drowsiness, nausea, slower breathing, and a general depression of the respiratory system. Further, opioids often cause constipation, or opioid-induced constipation (OIC). OIC is an uncomfortable side-effect that occurs in many patients who receive opioid treatments to relieve pain.
1. Colvin L, Forbes K, Fallon M; Difficult pain. BMJ. 2006; 332 (7549):1081-3
Disclaimer: This informational section on Medical News Today is regularly reviewed and updated, and provided for general information purposes only. The materials contained within this guide do not constitute medical or pharmaceutical advice, which should be sought from qualified medical and pharmaceutical advisers.
© MediLexicon International Ltd