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Definition of opioids
Last reviewed: 19.11.2021
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Opioids refer to substances that cause physical and psychological dependence. Opium is produced from opium poppy juice (Papaver somniferum), it contains more than 20 different alkaloids, the most famous of which is morphine. Semisynthetic alkaloids are obtained from morphine, including heroin (diacetylmorphine), codeine and hydromorphine. Synthetic opioids include trimeperidine, methadone, and others.
Of all the types of opiate addiction, the most common dependence on heroin. Heroin is much more active than morphine, it is better soluble and faster passes through the blood-brain barrier.
Opioids exert their effect by binding to specific opioid receptors in the brain. Areas of the brain that have a high affinity for exogenous opioids contain high concentrations of some endogenous peptides with opiate-like properties. These peptides are called endorphins (this term introduces a certain confusion due to the similarity to the name of one of the main prototypes of opioid peptides, β-endorphin, so the term "opio-peptides" is used to refer to the generic accessory to natural opioid peptides, and the term "endorphin" peptides closely associated with β-endorphin).
The main effects of opioids are related to the effect on the central nervous system. The most important of them include analgesia, euphoria, inhibition, respiratory depression, drowsiness and clouding of consciousness; there may be a violation of the ability to reason.
A significant portion of opioids are converted to polar metabolites, which are then rapidly excreted by the kidneys. Compounds that have free hydroxyl groups (morphine) are easily conjugated with glucuronic acid and are excreted in bile (but this is not the main pathway of excretion). Heroin (diacetylmorphine) is hydrolyzed to monoacetylmorphine, then to morphine, which is conjugated to glucuronic acid. Opioids are exposed in the liver and N-demethylation. The half-life of morphine is 2-4 hours, heroin - 1-1.5 hours, codeine - 2-4 hours.
Morphine and heroin addicts can take hundreds of milligrams of heroin; tolerant drug addicts take up to 5000 mg of morphine (in intolerant subjects death from an overdose can occur when taking 60 mg of morphine). Morphine and heroin withdrawal symptoms begin 6-8 hours after the last dose, reaches a maximum intensity during the 2nd-3rd day, and lasts 7-10 days (sometimes up to 6 months).
A lethal dose of morphine with ingestion of 0.5-1 g, with intravenous injection - 0.2 g. The lethal concentration in the blood is 0.1-4 mg / l. All opioids are especially toxic to children of younger age groups. A lethal dose of codeine for children under 3 years is 400 mg, heroin 20 mg.
Diagnosis of opioid overdose often does not cause difficulties (anamnesis, traces of injections), but in other cases it can be very complicated (as in any comatose state of unknown etiology). In such cases, it is necessary to examine the urine for the content of opiates. For this, various methods are used, both qualitative and quantitative.
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