Of opiates and opioids

Multiple opiate receptors Different regional distribution in the brain and differential binding of opiates and opioid peptides. Mol Pharmacol 16 91-104, 1979. 

Figure 3. Proposed model for the action of opiates and opioid peptides on glyco-syltransferase activity. It is postulated that receptors for both opiates and neurotransmitters are linked to adenylate cyclase by a guanylnucleotide regulatory protein (GNRP). The presence of opiates or opioid peptides inactivates the cyclase, which normally activates a protein kinase-glycosyltransferase system, thereby initiating...

These spontaneous events could prove of great interest and have already been shown to be of practical importance. Later, we describe how they have been used to explore the excitatory action of opiates and opioid peptides and possibly the time course of the unitary membrane events. Much earlier, a number of workers claimed to have recorded directly from interneurons involved in the spontaneous release of transmitter and showed them to be excited in a relevant way by orthodromic, but not antidromic, stimulation (Brown et al, 1979 Schwartzkroin and Mathers, 1978). 

Opiates and opioid derivatives delay the transit of intraluminal content or increase gut capacity, prolonging contact and absorption. The limitations of the opiates are addiction potential (a real concern with long-term use) and worsening of diarrhea in selected infectious diarrheas. 

The opium alkaloid morphine is representative for this group of opiates and also for other opioid analgesics. Morphine is a full agonist for both the jx and the k receptors. It is used to relieve severe acute pain, or chronic pain in terminally ill patients. Its oral bioavailability varies from 15% to 35% and its... 

While it is true that dextromethorphan is not technically a member of the opiate family, it is distantly related in its chemical composition. Dextromethorphan is created by from levomethorphan, which is classified as an opioid, the synthetic or semi-synthetic relatives of the natural chemical family called the opiates. Levomethorphan has most of the same qualities of all drugs in the opiate and opioid classes. This includes strong suppressive effects on the respiratory system. It is these strong effects on the respiratory system that make dextromethorphan an effective anti-cough agent. Opiate and opioid compounds have anti-cough properties but produce greater overall respiratory depression than dextromethorphan. 

Narcotics (opiates and opioids) are natural, semisynthetic, and synthetic derivatives of the opium poppy. Drugs such as morphine, codeine, heroin, methadone, Darvon, and Percodan fall into this category. They are all depressants, but they are also potent painkillers, and except for heroin (which is illegal) they are prescribed to relieve pain and to control coughing and diarrhea. But because of their pleasurable effects and addictive properties, they can cause problems when taken for nonmedical reasons. Most nonmedical users take these drugs to experience euphoria, to avoid pain, and to relieve withdrawal symptoms. —... 

Ramakrishnan. K, and Portoghe.se, P. S., Synthesis and biological evaluation of a mcla/o-cine-containing cnkephalinamide. Evidence for nonidentical roles of the tyraminc moiety in opiates and opioid peptides. J. Med. Chem, 25, 142.3, 1982. 

Opiates are compounds extracted from the milky latex contained in the unripe seed pods of the opium poppy (Papaver somniferum). Opium, morphine, and codeine are the most important opiate alkaloids found in the opium poppy. Opium was used as folk medicine for hundreds, perhaps thousands of years. In the seventeenth century opium smoking led to major addiction problems. In the first decade of the nineteenth century, morphine was isolated from opium. About 20 years later, codeine, one-fifth as strong as morphine, was isolated from both opium and morphine. In 1898, heroin, an extremely potent and addictive derivative of morphine was isolated. The invention of the hypodermic needle during the mid-nineteenth century allowed opiates to be delivered directly into the blood stream, which increases the effects of these drugs. Synthetically produced drugs with morphine-like properties are called opioids. The terms narcotic, opiate, and opioid are frequently used interchangeably. Some common synthetically produced opioids include meperidine (its trade name is Demerol) and methadone, a drug often used to treat heroin addiction. 

The term opiate has been used for the natural alkaloids of opium, and opioid for other agents having similar action. The distinction is neither generally observed nor particularly useful. We here use opioid for all receptor-specific substances. 

Heroin was first synthesized from morphine over a century ago. Since then, it has become one of the most abused substances. Research into why it produces such powerful effects has led to the discovery of specific opiate receptors and endogenous opioids (enkephalins and endorphins). These peptides appear to be neurotransmitters involved with the sensation of pain and pleasure. A number of opiates and synthetic opioids are available and can lead to dependency, including morphine, heroin, propoxyphene (Darvon), methadone, meperidine (Demerol), pentazocine (Talwin), hy-dromorphone (Dilaudid), oxycodone (Percodan), and hydrocodone (Vicodin, Damason-P), and codeine. 

Examples of Schedule II drugs are opiates and opioids (narcotics)—straight opiates of codeine, morphine, meperidine stimulants—amphetamine, methylphenidate depressants— amobarbital, pentobarbital, secobarbital, or any combination, that is, Tuinal hallucinogenic substances and any immediate precursors. 

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. 

Two opioids are used in the treatment and management of opiate dependence levomethadyl and methadone. Levomethadyl is given in an opiate dependency clinic to maintain control over the delivery of the drug. Because of its potential for serious and life-threatening proarrhythmic effects, levomethadyl is reserved for use in the treatment of addicted patients who have no response to other treatments. Levomethadyl is not taken daily the drug is administered three times a week (Monday/Wednesday/Thursday or Tuesday/Thursday/ Saturday). Daily use of the usual dose will cause serious overdose. 

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