Narcotic analgesics receptors

Narcotic analgesic. A drug that alleviates pain by interacting with the morphine receptor. 

Drug that counteract the effects of the narcotic analgesics are the narcotic antagonists. These drugp compete with the narcotics at the receptor sites and are used to reverse the depressant effects of the narcotic analgesics. Both types of drug are discussed in this chapter. 

Classification of the narcotic analgesics is based on their activity at the opioid receptor sites. Although five categories of opioid receptors have been identified, only three of these receptors affect the action of the narcotic... 

Inhibition constants (Kj) of 26 narcotic analgesic agonists and antagonists as obtained in 4 receptor binding tests (EKC, DHM, DADLE and NAL) [45],... 

Portoghese PS. A new concept on the mode of interaction of narcotic analgesics with receptors. J Med Chem 1965 8 609-616. 

Nalorphine has less of an analgesic effect than morphine however, it does not have much value as an independent analgesic. It is used as an antagonist to narcotic analgesics. It eliminates suppression of the respiratory center, bradycardia, and vomiting caused by opiate receptor agonists. 

It is worth mentioning that iV-allylic substitution in a number of morphine derivatives, as a rule, leads to antagonistic properties. Naloxone is a few times stronger than nalorphine as an antagonist. It blocks opiate receptors. It eliminates central and peripheral action of opioids, including respiratory depression. Naloxone is used upon overdose of narcotic analgesics.Synonyms for this drug are narkan, talwin, and others. 

Analgesic, respiratory, depression as well as euphoria produced by morphine result mainly from action at mu receptors. Most of the currently available narcotic analgesics act primarily on the mu receptors. 

This situation became particularly acute with respect to the development of illicit analogs of fentanyl to derive heroin substitutes. Fentanyl is a synthetic opioid, a p-receptor agonist, and is about 100-200 times more potent than morphine as an analgesic. As with other narcotic analgesics, respiratory depression is the most significant acute toxic effect of the fentanyl derivatives. Fentanyl analogs can be 80-1000... 

Opioid receptor affinity labels have been reported for other narcotic analgesics, for example, piperidines, 293 294 benzomorphans, 295 296 and mor-phinans, 297,298 and the topic is further discussed in Chapter 13 (p. 445). Not only is the oxo-function in the 4,5-epoxymorphinan C-ring available for ready elaboration, but C-6 substituents, although they affect agonist potency, do not impair unduly receptor affinity. 299 301 ... 

All compounds that behave as narcotic analgesics characterized by the usual criteria contain a basic nitrogen center that either forms parts of an alicyclic ring system, as in morphine and pethidine, or terminates an acyclic chain, as in methadone, etonitazene, and the enkephalins. Nonbasic compounds of high activity in antinociceptive tests invariably fail to satisfy criteria for narcotic analgesics, such as reversal of effects by naloxone or nalorphine or evidence of binding to opioid receptors recent examples are the barbiturate... 

Opium. 2. Analgesics. 3. Analgesics—Receptors. 4. Narcotics—Receptors. 5. Endorphins—Receptors. I. Parfitt, Robert T. II. Title. [DNLM 1. Endorphins. 2. Narcotics. 3. Receptors, Endorphin. QV 89 C338ol... 

Narcotic antagonists have higher affinity to the opiate receptor site than the narcotic analgesic, resulting in blocking the narcotic analgesic from binding to the opiate receptor site. 

Category Analgesic, narcotic NMDA receptor antagonist... 

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