An opioid is any psychoactive chemical that resembles morphine or other opiates in its pharmacological effects. Opioids work by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract. The receptors in these organ systems mediate both the beneficial effects and the side effects of opioids.
Although the term opiate is often used as a synonym for opioid, the term opiate is properly limited to the natural alkaloids found in the resin of the opium poppy (Papaver somniferum), while opioid refers to both opiates and synthetic substances, as well as to opioid peptides.
Opioid dependence can develop with ongoing administration, leading to a withdrawal syndrome with abrupt discontinuation. Opioids are not only well known for their addictive properties, but also for their ability to produce a feeling of euphoria, motivating some to use opioids recreationally.
- 1 Chemistry
- 2 Pharmacology
- 3 Subjective effects
- 4 Pharmacological classes
- 5 Toxicity and harm potential
- 6 See also
- 7 References
Opioids are based upon morphine and opium-like structures. They work via their similar chemical structures to the endogenous opioids in the body. Morphine derived opioids, known as morphinans, contain a benzene ring attached to two partially unsaturated cyclohexane rings (phenanthrene) and a 4th nitrogenous ring attached to the core at carbons 9 and 13. There are several classes of opioids which differ greatly in structure from each other. For example, fentanyl and its analogues are structurally unique from morphinans and tramadol derivaties.
Opioids are known to mimic endogenous endorphins. Endorphins are responsible for analgesia (reducing pain), causing sleepiness, and feelings of pleasure. They can be released in response to pain, strenuous exercise, orgasm, or excitement. This mimicking of natural endorphins results in the drug's euphoric, analgesic (pain relief) and anxiolytic (anti-anxiety) effects.
Opioids act on the three main classes of opioid receptor in the nervous system, μ, κ, δ (mu, kappa, and delta). Each opioid is measured by its agonistic or antagonistic effects towards the receptors, with the responses to the different receptor sub-types (e.g., μ1 and μ2) providing even more effects. Opioid receptors are found mainly within the brain, but also within the spinal cord and digestive tract.
The delta receptor is responsible for the analgesia, antidepressant and convulsant effects as well as physical dependence.
The zetta opioid receptor, also known as opioid growth factor receptor (OGFr) is responsible for tissue growth, neural development, and is further implicated in the development in some cancers. The endogenous ligand for OGFr is met-enkephalin, which is also a powerful endogenous delta opioid receptor agonist.
The effects listed below are based upon the subjective effects index and personal experiences of PsychonautWiki contributors. The listed effects should be taken with a grain of salt and will rarely (if ever) occur all at once, but heavier doses will increase the chances and are more likely to induce a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include injury or death.
- Euphoria - This sensation can be described as extreme feelings of intense physical comfort, warmth, and all-encompassing bliss.
- Respiratory depression - At low to moderate doses, this effect results in the sensation that the breath is slowed down mildly to moderately, but does not cause noticeable impairment. At high doses and overdoses, opioid-induced respiratory depression can result in a shortness of breath, abnormal breathing patterns, semi-consciousness, or unconsciousness. Severe overdoses can result in a coma or death without immediate medical attention.
- Pain relief
- Cough suppression
- Decreased libido
- Difficulty urinating
- Stomach cramps
- Pupil constriction
- Orgasm suppression
- Internal hallucinations - One may experience feelings of hypnagogia during a state of "nodding" which is often accompanied by vivid dream-like visions.
Toxicity and harm potential
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When used in safe dosages, in terms of physical and neurological toxicity most opiods are markedly safe with the long-term effects generally consisting of constipation. The negative aspects associated with opioids do not stem from physiological toxicity but psychological addiction and dependence.
It is strongly recommended that one use harm reduction practices when using this class of substances.
Tolerance and addiction potential
Due to the highly euphoric nature of these substances, the recreational use and abuse of opioids has an extremely high rate of addiction and dependence. This is combined with a tolerance which builds up quickly, necessitates that the user take increasingly high dosages in order to get the same effects.
The risk of fatal opioid overdoses rise sharply after a period of cessation and relapse, largely because of reduced tolerance. To account for this lack of tolerance, it is safer to only dose a fraction of one's usual dosage if relapsing. It has also been found that the environment one is in can play a role in opioid tolerance. In one scientific study, rats with the same history of heroin administration were significantly more likely to die after receiving their dose in an environment not associated with the drug in contrast to a familiar environment.
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- Risks of Combining Depressants (Tripsit) | https://tripsit.me/combining-depressants/
- Why Heroin Relapse Often Ends In Death - Lauren F Friedman (Business Insider) | http://www.businessinsider.com.au/philip-seymour-hoffman-overdose-2014-2
- Siegel, S., Hinson, R., Krank, M., & McCully, J. (1982). Heroin “overdose” death: contribution of drug-associated environmental cues. Science, 216(4544), 436–437. https://doi.org/10.1126/science.7200260