Levorphanol

The synthesis of dextromethorphan is an outgrowth of early efforts to synthesize the morphine skeleton. /V-Methy1morphinan(40) was synthesized in 1946 (58,59). The 3-hydroxyl and the 3-methoxy analogues were prepared by the same method. Whereas the natural alkaloids of opium are optically active, ie, only one optical isomer can be isolated, synthetic routes to the morphine skeleton provide racemic mixtures, ie, both optical isomers, which can be separated, tested, and compared pharmacologically. In the case of 3-methoxy-/V-methylmorphinan, the levorotatory isomer levorphanol [77-07-6] (levorphan) was found to possess both analgesic and antitussive activity whereas the dextrorotatory isomer, dextromethorphan (39), possessed only antitussive activity. Dextromethorphan, unlike most narcotics, does not depress ciUary activity, secretion of respiratory tract fluid, or respiration. 

Demethylation of the acetyl derivative (47) of levorphanol affords desmethyl compound, 48. Hydrolytic removal of the acetate (49) followed by alkylation with allyl bromide affords the narcotic antagonist levallorphan (50), an agent with properties... 

Morphine, when extracted from raw opium and treated chemically, yields the semisynthetic narcotics hydromorphone, oxymorphone, oxycodone, and heroin. Heroin is an illegal narcotic in the United States and is not used in medicine. Synthetic narcotics are those man-made analgesics with properties and actions similar to the natural opioids. Examples of synthetic narcotic analgesics are methadone, levorphanol, remifen-tanil, and meperidine Additional narcotics are listed in the Summary Drug Table Narcotic Analgesics. 

C,H2N02 372-09-8) see Cyclopentamine Levorphanol Pyrantel Sulindac cyanoacetyl chloride... 

C H, 0 108-94-1) see Calusterone Clinofibrate Cyclobarbital Cyclobutyrol Cyclovalone Ethinamate Gabapentin Guanadrel Hexobarbital Levorphanol Orlistat Ramatroban Tacrine Tenylidone Venlafaxine 2-cyclohexen-l-one (CjHjO 930-68-7) see Carprofen... 

Opiates activate the chemoreceptor trigger zone in the medulla (by disinhibition) to cause nausea and vomiting, and cough suppression also occurs because of the inhibitory effects of opiates on the brainstem nuclei in the cough reflex pathway. Dextromethorphan is the non-opiate isomer of the opiate levorphanol and is an effective cough suppressant. 

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