Codeine-narcotine salts

Codeine will form an addition compound with carbon suboxide, in the proportions 1 5, which is stable to oxygen and water [381], with phenolphthalein [382], and withp-acetamidophenol [383]. Codeine forms double salts with narcotine [384-5], and salts with numerous barbituric acid derivatives [386-92], of therapeutic interest. 

Two of the principal alkaloids of opium are morphine (4-21%) and a a-narcotine (noscapine) (4-8%) (63). These alkaloids occur partially bound to meconic acid, which is diagnostic for opium. Morphine (58) and its salts are classified as narcotic analgesics. Codeine (62) also occurs in opium, in the concentration range 0.7-2.5%. Most codeine (62) is prepared by methylation of morphine. 

In modem medicine, mily the purified opium alkaloids and their derivatives are commonly employed. Although the ripe poppy capsule can contain up to 0.5 % total alkaloids, opium represents a much concentrated form and up to 25 % of its mass is composed of alkaloids. Of the many (>40) alkaloids identified, some six represent almost all of the total alkaloid content. Actual amounts vary widely, e.g., morphine (4-21 %), codeine (0.8-2.5 %), thebaine (0.5-2.0 %), papaverine (0.5-2.5 %), noscapine (narcotine) (4—8 %), and narceine (0.1-2 %). A t3q>ical commercial sample of opium would probably have a morphine content of about 12 %. Powdered opium is standardized to contain 10 % of anhydrous morphine, usually by dilution with an approved diluent, e.g., lactose or cocoa husk powder. The alkaloids are largely combined in salt form with meconic acid, opium containing some 3-5 % of this material. Meconic acid is invariably found in opium but, apart from its presence in other Papaver species, has not been detected elsewhere. It gives a deep red-colored complex with ferric chloride, and this has thus been used as a rapid and reasonably specific test for opium. Of the main opium alkaloids, only morphine and narceine display acidic properties, as well as the basic properties due to the tertiary amine. Narceine has a carboxylic acid function, while morphine is acidic due to its phenolic hydroxyl. This acidity can be exploited for the preferential extraction of these alkaloids (principally morphine) from an organic solvent by partitioning with aqueous base (Table 15.6). 

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