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Although the term opiate is often used to refer to all opium-like drugs, it is more properly limited to the natural opium alkaloids and the semi-synthetics derived from them.
Main article: opioid receptor
There are at least three major classes of opioid receptors: μ, κ and δ. These are all G-protein coupled receptors acting on GABAergic neurotransmission . The μ receptor (the μ represents morphine) is perhaps the most important - being responsible for for most of the analgesic and other major pharmacological effects as well as many of the adverse effects of opioids.
Opioid overdoseOverdose is a medical term which describes the action of consuming an excessive amount of a drug. See drug overdose. Such an action will result in side effects such as: sweating high blood pressure headache migraine confusion vertigo nausea vomiting death can be rapidly reversed with any of several opioid antagonistThis article refers to literary antagonists. For the biological meaning, see receptor antagonist . The antagonist is the character (or group of characters) of a story who represents the opposition against which the heroes and/or protagonists must contend.s - these competitive antagonistA competitive antagonist is a receptor antagonist which binds to a receptor but fails to activate it. If an agonist competes with a competitive antagonist for the same binding site on the same receptor, the agonist molecules can be displaced from the binds are drugs that bind to the μ-opioid receptors with higher affinity than agonists but do not activate them. This displaces the agonist, attenuating and/or reversing the agonist effects.
Opioids are widely used in medicine as strong analgesicsAn analgesic is any member of the diverse group of drugs used to relieve pain. Analgesic drugs include the nonsteroidal anti-inflammatory drugs (NSAIDs) such as the salicylates, narcotic drugs such as morphine, and synthetic drugs with narcotic properties (pain relievers). Despite extensive research, to date no analgesics have been found that are more effective for severe pain. One of the advantages of opioids is that here is no upper limit to the dosage and the achievable pain relief as long as the dose is increased gradually to allow tolerance to develop to adverse effects (especially respiratory depression).
The main clinical indications of opioids include (Rossi, 2004):
Opioids have long been used to treat acute pain (such as post-operative pain). They have also found to be invaluable in palliative care to alleviate the severe, chronic, disabling pain of terminal conditions such as cancer. Very high doses are often required in palliation to improve the patients' terminal quality-of-life.
In recent years there has been an increased use of opioids in the management of non-malignant chronic pain. While this trend is still somewhat controversial in some circles, due to issues of dependence, the emerging medical consensus is that most chronic pain patients can safely use opioids for years with a minimal risk of addiction or toxicity and that the overall increase in quality of life outweighs any adverse effects of opioid-use.
As recently as the early 20th century, opioids were administered by doctors to treat severe depression and other psychiatric disorders. The practice was discontinued because of the dependence-producing nature of opioids.