Of morphine

The first reaction was involved in a synthesis of morphine, the starting ketone being made by reduction of a substituted naphthalene O. Amer. Chem. Soc., 1950, 72, 3704). No doubt an epoxide could have been used as the electrophile. 

In the synthesis of morphine, bis-cyclization of the octahydroisoqtiinolinc precursor 171 by the intramolecular Heck reaction proceeds using palladium trifluoroacetate and 1,2,2,6,6-pentamethylpiperidine (PMP). The insertion of the diene system forms the rr-allylpalladium intermediate 172, which attacks the phenol intramolecularly to form the benzofuran ring (see Section 1.1.1.3). Based on this method, elegant total syntheses of (-)- and (+ )-dihydrocodei-none and (-)- and ( + )-morphine (173) have been achieved[141]. 

An interesting set of central nervous system properties has also been discovered and studied (Table VI-10). The work devoted to piscaine must be emphasized besides finding hypnotic properties of 2-amino-4-phenyl-thiazole on fish, the authors studied the structure of the metabolite, as well as the localization of the (radio labeled) metabolic product in various organs. Recently, thiazol-4-yl methoxyamine was shown to inhibit the development of morphine tolerance (1607). 5-Aminothiazole derivatives such as 419a were proposed as cardiovascular agents (1608, 1610). Substitution of the 5-aminothiazole radical on the cephalophosphorin structure gives a series of antibacterial products (1609). 

An opium alkaloid Although it is an excellent analgesic its use is restricted because of the potential for addiction Heroin is the diacetate ester of morphine )... 

Salem and Galan have developed a new method for determining the amount of morphine hydrochloride in tablets. Results, in milligrams, for several tablets containing different nominal dosages follow... 

The concentration of alkaloids, as well as the specific area of occurrence or localization within the plant or animal, can vary enormously. Thus the amount of nicotine [54-11-5] (21), C2QH24N2, apparentiy synthesized ia the roots of various species of JSHcotiana and subsequentiy translocated to the leaves varies with soil conditions, moisture, extent of cultivation, season of harvest, etc and may be as high as 8% of the dry leaf, whereas the amount of morphine (2, R = H) ia cerebrospiaal duid is of the order of 2 to 339 fmol/mL (23). 

Codeiae (2, R = CH3) occurs ia the opium poppy along with morphine (2, R = H) but usually ia much lower concentration. Because it is less toxic than morphine and because its side effects (including depression, etc) are less marked, it has found widespread use ia the treatment of minor pain and much of the morphine found ia cmde opium is converted to codeiae. The commercial coaversioa of morphine to codeiae makes use of a variety of methylating ageats, amoag which the most common are trimethylphenylammonium salts. Ia excess of two huadred toas of codeiae are coasumed anauaHy from productioa faciUties scattered arouad the world. 

The first syathesis of morphine, and therefore also codeiae, was completed ia 1956 (58). Although an additional twelve or so syntheses have been reported siace then, isolation of morphine remains more important than any synthetic process. However, synthetic endeavors continue to demonstrate new synthetic tools and capabiUties and to conduct the search for modified analogues that retain the analgesic properties of morphine but are nonaddicting. 

The Opiates. The International Narcotics Control Board—Vienna, tracks the tick production of narcotic dmgs and annually estimates world requkements for the United Nations. Thek most recent pubHcation (100) points out that more than 95% of the opium for Hcit medical and scientific purposes is produced by India and, in a declining trend, only about 600 t was utilized in 1988. This trend appears to be due to the fact that the United States, the largest user of opium for alkaloid extraction, reduced the amount of opium being imported from about 440 t in 1986 to 249 t in 1987 and 224 t in 1988. The United States used about 48 t of morphine (2, R = H) in 1988, most (about 90%) being converted to codeine (2, R = CH3) and the remainder being used for oral adrninistration to the terminally ill (about 2 t) and for conversion to other materials of minor commercial import which, while clearly alkaloid-derived, are not naturally occurring. 

The iaterpretation of forensic toxicology (18) results is often challenging. Courts frequently ask if an amount of dmg detected ia a specimen could cause a specific type of behavior, ie, would someone be under the influence of a dmg at a specific concentration, would a particular dmg concentration cause diminished capacity, or was the dmg the cause of death In a random employee dmg testing case, a worker screened positive for opiates by EMIT and gc/ms analysis of the urine specimen showed low levels of morphine. Although one possibiUty was that the iadividual was a heroia user, a review of foods eaten ia the prior 24 hours suggested a more innocent cause a poppy-seed bagel. 

P-Endorphin. A peptide corresponding to the 31 C-terminal amino acids of P-LPH was first discovered in camel pituitary tissue (10). This substance is P-endorphin, which exerts a potent analgesic effect by binding to cell surface receptors in the central nervous system. The sequence of P-endorphin is well conserved across species for the first 25 N-terminal amino acids. Opiates derived from plant sources, eg, heroin, morphine, opium, etc, exert their actions by interacting with the P-endorphin receptor. On a molar basis, this peptide has approximately five times the potency of morphine. Both P-endorphin and ACTH ate cosecreted from the pituitary gland. Whereas the physiologic importance of P-endorphin release into the systemic circulation is not certain, this molecule clearly has been shown to be an important neurotransmitter within the central nervous system. Endorphin has been invaluable as a research tool, but has not been clinically useful due to the avadabihty of plant-derived opiates. 

The CCK system shares one property with the opioid system, ie, the existence of selective nonpeptide antagonists. These include aspedicine, a natural benzodiazepine (136), and Devazepide (L-364,718 MK-329) (137). Selective, potent peptide antagonists for CCK, eg, Cl-988 and PD 134308, have been developed that maybe useful as anxiolytics and as dmgs which increase the analgesic effect of morphine but at the same time prevent morphine tolerance (138) (see Hypnotics, sedatives, anticonvulsants, and anxiolytics). 

Codeine, mol wt 299.3, is a significantly less potent analgesic than morphine, requiring 60 mg (0.20 mmol) to equal the effectiveness of 10 mg (0.04 mmol) of morphine. However, codeine is orally effective, and it is less addictive and associated with less nausea than morphine. Codeine is used as an antitussive agent, although newer, nonaddictive agents are preferred (see Expectorants, antitussives, and related agents). 

Fig. 1. Conformational representation of the piperidine ring of morphine (1) and analogues meperidine (7, R = H, R = COOC2H ) and alphaprodine (7, R = R = 0CC2H ). The chiral center of interest in stmcture (7) is starred (see text).

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... 

The quest for compounds that combined the analgesic properties of morphine, were nonaddictive, and lacked the side effects of nalorphine, led to the development of the dmgs shown in Table 3. These compounds have both agonist and antagonist activities. Nalbuphine (14) (23) and buprenorphine... 

Codeine, like morphine, is isolated from the opium poppy. However, the low yield of 0.7—2.5% does not provide sufficient material to meet commercial demands. The majority of marketed codeine is prepared by methylating the phenolic hydroxyl group of morphine. Morphine yields from opium poppy are 4—21%. When prescribed for cough, the usual oral dose is 10—20 mg, three to four times daily. At these doses, adverse side effects are very few. Although the abuse potential for codeine is relatively low, the compound can substitute for morphine in addicts (47). 

Molecular modifications of the morphine skeleton have produced numerous derivatives with antitussive properties, some of which have become commercially significant. Ethyknorphine [76-58-4] (29), a simple homologue of codeine, is prepared by ethylating morphine. It is pharmacologically similar to codeine but is seldom used clinically. Pholcodine [509-67-1] (30), the morpholinoethyl derivative of morphine, is used as an antitussive in a number of European countries. It is about one and a half times as potent as codeine, has Htde or no analgesic activity, and produces minimal physical dependence. The compound is prepared by the amino alkylation of morphine (48). 

Hydromorphone [466-99-9] (31) and hydrocodone [125-29-1] (32) are isomers of morphine and codeine, respectively. Hydromorphone can be prepared by catalytic rearrangement of morphine (49) or by oxidation of the aliphatic hydroxyl group of dihydromorphine (50). Hydrocodone can be similarly prepared. As an antitussive, hydromorphone is several times more active than morphine and hydrocodone is slightly more active than codeine. Hydromorphone has a much higher addiction potential than hydrocodone. 

Noscapine [128-62-1] (45) is the second most abundant alkaloid found in opium. Unlike most opium alkaloids, however, it has an isoquinoline rather than a phenanthrene ting system. Noscapine was first isolated in 1817 but its antitussive activity was not demonstrated pharmacologically until 1952 (63). Clinical studies have confirmed its effectiveness. It is not a narcotic and has a wide margin of safety when given orally. Death could be produced in rats only with doses > 800 mg/kg (64). Noscapine is isolated from the water-insoluble residue remaining after processing opium for the manufacture of morphine. 

More interesting, as regards future developments, are the eiforts now being made to dispense with opium as an intermediate in the production of morphine. The early history of experiments in the direct extraction of the alkaloid from poppy capsules and poppy straw has been recounted by Goris and by Wiiest and Frey. ... 

Wiiest and Frey have pointed out that poppy straw has disadvantages in low yield of morphine and in bulkiness, and prefer poppy heads as a primary material. Many samples of capsules from seven countries were examined by them and found to yield from 0-18 to 0-9 per cent, of morphine, and they conclude that it should be possible to get ripe, dry capsules containing on the average 0-3 to 0-5 per cent, of morphine. Their paper includes a description of a process of analysis, which was found speedy and accurate. 

In the experiments in Australia, described by Barnard and Finnemore, the average yield of morphine from capsules of two varieties of poppy, ranged from 0- 29 to 0- 39 and from 0- 26 to 0- 30 and from the whole plant from 0-09 to 0-16 and from 0-12 to 0-18 per cent. 

For use in medicine, opium is dried, powdered and standardised to a definite content of morphine, which the British Pharmacopoeia 1932 places at 10 per cent, (limits 9-5 and 10-5), and the United States Pharma-copceia (XIII) at not less than 10 or more than 10-5 per cent. 

Estimation of Morphine in Opium. The problem of determining with reasonable accuracy the percentage of morphine in opium is of importance for the standardisation of medicinal opium, as a means of fixing the price of crude opium, and of controlling factory operations in the extraction of... 

The amount of morphine in commercial opium varies from 3 to 25 per cent. In Macedonian and Turkey opiums the pereentage is usually 15 to 21, and in the Persian drug 10 to 12. Indian opium, as prepared for smoking, may eontain 4 to 6 per cent., but as exported for the manu-... 

The processes used in the manufacture of morphine are believed to be still based on that described by the Scottish chemist Gregory,in 1833, with improvements devised by Anderson. A description has been published by Schwyzer, who also deals with the manufactme of codeine, narcotine, cotarnine, and the commercially important morphine derivatives, diamorphine (diacetylmorphine), and ethylmorphine (morphine ethyl ether). More recently Barbier has given an account of processes, based on long experience in the preparation of alkaloids from opium. Kanewskaja has described a process for morphine, narcotine, codeine, thebaine and papaverine, and the same bases are dealt with by Chemnitius, with the addition of narceine, by Busse and Busse, and by Dott. It is of interest to note that a number of processes for the extraction and separation of opium alkaloids have been protected by patent in Soviet Russia. ... 

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