Strong opioid analgesics

These opioid analgesics are used for severe pain poorly localized in the internal organs

In the localized pain of lower intensity use weak narcotic or narcotic opioid analgesics (nonsteroidal anti-inflammatory drugs, see Chapter 32). To eliminate the severe pain morphine is administered parenterally, oral administration of morphine is shown in the terminal stages of illness.
Morphine and other opioids have a variety of central effects. Besides pronounced opioid analgesics narcotic analgesics cause a state of euphoria, depression of the respiratory and vasomotor centers (which may lead to orthostatic hypotension), have a sedative effect, encourage the trigger hemoreceptor zone (causing nausea and vomiting). Opioids stimulate the center of the oculomotor nerve, causing a contraction of the pupil - miosis (the exception is pethidine, which has a weak m-anticholinergic activity). Drugs inhibit the cough center, but the severity of this effect does not correlate with their opioid activity. In the application of opioids may be constipation, spasms of the bile ducts and sphincter of Oddi. Morphine can cause histamine liberatsiyu, which leads to vasodilatation and the appearance of skin itch. Morphine is metabolized in the liver by conjugation with glucuronic acid, forming inactive morphine-3-glucuronide and morphine-highly active 6-glucuronide.
Prolonged use of opioid analgesics develops tolerance to them (ie, addiction - reduction in sensitivity to the drug). Such side effects of narcotic analgesics, a contraction of the pupil and constipation, do not improve after prolonged use.

For opioid analgesics develops mental and physical drug dependence, abrupt withdrawal of drugs causing withdrawal symptoms

Diamorphine (heroin, diacetylmorphine) is two times more active than morphine. The body is rapidly converted to the active metabolite 6-atsetilmorfin and more slowly to morphine. In the application of heroin observed pronounced euphoria, nausea, constipation, and hypotension are less pronounced than with morphine.
Methadone is well absorbed when taken orally, has a lasting effect. It is used orally in the treatment of opiate addiction for the prevention of withdrawal syndrome ("breaking").
Pethidine has properties similar to morphine, but shorter acting. When used in doses causing analgesia, depresses the respiratory center, has a weak anti-tussive effect and practically no development of constipation. The drug is highly lipophilic, so its effect develops rapidly. The liver becomes norpetidin pethidine, which can cause a number of side effects (eg, mydriasis, seizures). The combined use of pethidine with MAO inhibitors may cause the appearance of delirium, fever, convulsions and respiratory depression.
Buprenorphine - a partial agonist m-receptors, lipophilic, is effective for sublingual application. The drug has a longer than morphine. Using it may cause prolonged vomiting. Buprenorphine is closely associated with opioid receptors, naloxone, so practically does not eliminate the respiratory depression caused by the use of the drug.
    Nalbufin (agonist to the receptor and receptor antagonist m-) corresponds to morphine analgesic activity and the ability to inhibit the respiratory center, nausea and vomiting if it is applied less frequently observed. When opioid analgesics used in high doses causes dysphoria.