Naloxon

Opiates iateract with three principal classes of opioid GPCRs )J.-selective for the endorphiQS,5-selective for enkephalins, and K-selective for dynorphias (51). AU. three receptors have been cloned. Each inhibits adenylate cyclase, can activate potassium channels, and inhibit A/-type calcium channels. The classical opiates, morphine and its antagonists naloxone (144) and naltrexone (145), have moderate selectivity for the. -receptor. Pharmacological evidence suggests that there are two subtypes of the. -receptor and three subtypes each of the 5- and K-receptor. An s-opiate receptor may also exist. 

Fig. 4. Structures of several nonpeptide opioid agonists, (a) morphine, (c) BW373U86, (e) U50488 and antagonists, (b) naloxone, (d) naltrindole, and (f)...

The replacement of the /V-methyl group on the nitrogen atom of the piperidine ring of morphine and analogues by aHyl, isopropyl, or methyl cyclopropyl, an isopropyl isostere, results in compounds which antagonize opioid responses, especially respiratory depression. Naloxone [465-65-6] C22H2 N04 (10... 

Zipeprol [34758-83-3] (58) is another European antitussive with a wide range of pharmacological effects, including antispasmodic, antihistaminic, and local anesthetic activities (85,86). It has been reported that zipeprol has been abused in Italy because high doses cause hallucinations (87). Spontaneous withdrawal symptoms similar to those of opiates have been observed withdrawal symptoms can also be precipitated by naloxone. Zipeprol can be... 

Mesoridazine besylate Methoqualone Metoclopramide HCI Metolazone Midazolam maleate Moxisylyte Nadolol Naloxone... 

Azapetine phosphate Methohexital sodium Nalorphine Naloxone... 

Opiate overdose is a medical emergency that can result in respiratory and CNS depression. The opioid receptor antagonist naloxone immediately reverses cardiorespiratory depression. However, repeated naloxone administration is required, since the effects of naloxone last for 30 min, while opioid agonists can remain at potentially lethal blood levels for several hours. 

The pharmacological and/or adverse effects of a drug can be reversed by co-administration of drugs which compete for the same receptor. For example, an opioid receptor antagonist naloxone is used to reverse the effects of opiates. Drugs acting at the same site with opposite effects also can affect each other, e.g. the reduction in the anticoagulant effect of warfarin by vitamin K. 

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