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:''For other uses see Opiate (disambiguation), or for the class of drugs see Opioid.''
In medicine, the term 'opiate' describes any of the narcotic alkaloids found in opium.
The main opiates derived from opium are morphine, codeine, thebaine, and Papaverine, Noscapine, narceine and approximately 25 other alkaloids are also present, but have essentially little to no effect on the central nervous system, and are not usually considered to be opiates. Heroin, though well different from alkaloids, is also an opiate. The pharmacology of heroin and morphine is identical except that the two acetyl groups slightly increase the lipid solubility of the heroin molecule, and thus the molecule enters the brain a bit more rapidly, making the heroin molecule slightly more potent.[1] The additional groups are then detached, yielding morphine, which is the molecule that binds to the opioid receptors and produces analgesia, sedation, and other effects. In this case, heroin is just a prodrug for the delivery of systemic morphine.
Some papers [2] [3]
[4] [5] [6] state that the metabolite Monoacetylmorphine makes heroin a different drug that probably binds on a different receptor subtype, but this is wrong. "Heroin" is just a more rapid-acting form of morphine.[7]
Codeine, morphine and heroin metabolites are so similar, that it is impossible to distinguish whether heroin, codeine or morphine has been taken when low concentrations of opioids are found in the urine.[8]
Morphine is by far the most prevalent and important alkaloid in opium, consisting of anywhere from 10% to 16% of the total, and is responsible for most of its harmful effects such as lung edema, respiratory difficulties, coma, or cardiac or respiratory collapse, with a normal lethal dose of 120 to 250 mg.[9] (approximately two grams of opium.[10]) Despite morphine being the most medically significant alkaloid, larger quantities of the milder codeine—most of it manufactured from morphine—are consumed medically.
The expression of the morphine content of opium as a percentage depends in part on the moisture content. When the government purchases the opium as soon as practicable after it is collected, the moisture content is then usually about 30%. Commercial opium usually has around 10 to 15% moisture. Opium apparently dried at ordinary temperatures still retains considerable moisture—usually about six percent—which can be driven off at about 103 degrees Celsius.
The quantity of morphine produced by poppy plants in the form of opium depends on two factors: the percentage of morphine in the opium, and the quantity of opium produced. The latter factor in turn depends in part on whether each capsule is bled several times, or just once. In Turkey, Bulgaria, Greece and the Balkans, each capsule is bled only once, but in most other opium-producing countries, like Iran, India, and Afghanistan, the capsules are incised repeatedly, often four or five times on different days, until they will yield no more latex. The quantity of latex falls off rapidly with later incisions, and so does the morphine content.[11] Usually, all the opium obtained is mixed together. This is probably the chief reason for the often lower morphine content of Iranian and Indian opiums as compared with Turkish and Balkan opiums, although it must also be recognized that there are low-yielding and high-yielding strains of the poppy, one or the other of which may predominate in a given region.
Samples of opium assaying some 15% morphine from Japan, Indochina and Afghanistan, as well as from Turkey, Greece and the Balkans have been examined by the Secretariat. Afghanistan at one time exported two grades of opium, one of about 15% morphine and the other about 10%. The morphine content of dry capsule-chaff is about 0.25% to 0.5%, when not washed out by rain. Here again there are low-yielding and high-yielding varieties, but proper agricultural selection of poppies for morphine production means taking into account not only the percentage yield of morphine, but also the total weight of capsule-chaff produced per hectare, the poppy seed production per hectare, and other factors.
Most of the licit morphine is used to manufacture codeine through O-methylation. Morphine is also used to manufacture other drugs like apomorphine (not subject to the conventions), dihydromorphine, hydromorphone and many others. Through acetylation (in the form of the pro-drug—"heroin"), morphine becomes more lipid soluble, and thus, the morphine enters the brain more rapidly.[1]
The codeine content of opium is related inversely to the morphine content but only in a general way. Codeine yield is closely related to the type of opium produced in a given district or even in some cases in an entire country. The opiums of the principal exporting countries have approximately the following percentages of codeine: Balkans 1.25%; Turkey 1.25%; Iran 3.4%; India 3.0%.
The highest percentages of codeine obtained by the Secretariat (averaging about 4.3%) were found in opium samples which came from north-eastern Asia (Korea, northern China).
The manufacturers’ statistics do not ordinarily show all the codeine obtained from opium. Some of it co-precipitates with the morphine, and there is no necessity of purifying the morphine completely of its codeine content, especially if it is to be used to manufacture more codeine.
Codeine is used to manufacture dihydrocodeine, hydrocodone, and others. It may also be used to manufacture the drugs ordinarily made by conversion of thebaine.[2]
The United Nations Secretariat is currently engaged in a survey, the most extensive ever attempted in this field, of opium samples from different regions for their thebaine and papaverine percentages. As yet, it is premature for general conclusions. However, the highest thebaine percentages found (nearly 5%) were in some samples from Indochina, which at the same time had virtually no papaverine. Both thebaine and papaverine have been high in most Iranian samples run. Papaverine is low in some Afghan and Indian opiums.
Thebaine is the most poisonous opium alkaloid and is scarcely used medically. It is even omitted from some of the preparations of mixed opium alkaloids which are used as soluble substitutes for opium. However, it is converted into several other narcotics which have medical use: hydrocodone, acetyldihydrocodeine, oxycodone, and the highly potent and powerful narcotic, oxymorphone.
Papaverine has a considerable medical use, so much so that supplies available from opium have sometimes run short. It is then manufactured synthetically.[3]
''Opiate'' has traditionally referred to not only the alkaloids in opium, but also natural and semi-synthetic derivatives of morphine (itself an opiate). The term is often incorrectly used to refer to all drugs with opium- or morphine-like pharmacological action, which are more properly classified under the broader term ''opioid''.
1. http://www.u.arizona.edu/~tommyb/Opiates.html
2. http://jpet.aspetjournals.org/cgi/content/abstract/129/2/144
3. http://jpet.aspetjournals.org/cgi/content/full/299/2/760?ck=nck
4. http://www.nida.nih.gov/DirReports/DirRep297/DirectorReport1.html
5. http://opioids.com/6-monoacetylmorphine/index.html
6. http://www.ricercaitaliana.it/prin/dettaglio_completo_prin_en-2004052391.htm
7. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2420426&dopt=Abstract
8. http://preventiontraining.samhsa.gov/CMHC01/MOD8PM.htm
9. Mallinckrodt MSDS
10. Narcotic Drugs Anil Aggrawal
11. Annett, Harold Edward, "Factors Influencing Alkaloidal Content and Yield of Latex in the Opium Poppy (Papaver somniferum)". Biochemical Journal, 14, 618–36 (1920).
Scoring the poppy pod.
In medicine, the term 'opiate' describes any of the narcotic alkaloids found in opium.
| Contents |
| Overview |
| The alkaloids |
| Morphine |
| Codeine |
| Thebaine and Papaverine |
| Terminology |
| References |
Overview
The main opiates derived from opium are morphine, codeine, thebaine, and Papaverine, Noscapine, narceine and approximately 25 other alkaloids are also present, but have essentially little to no effect on the central nervous system, and are not usually considered to be opiates. Heroin, though well different from alkaloids, is also an opiate. The pharmacology of heroin and morphine is identical except that the two acetyl groups slightly increase the lipid solubility of the heroin molecule, and thus the molecule enters the brain a bit more rapidly, making the heroin molecule slightly more potent.[1] The additional groups are then detached, yielding morphine, which is the molecule that binds to the opioid receptors and produces analgesia, sedation, and other effects. In this case, heroin is just a prodrug for the delivery of systemic morphine.
Some papers [2] [3]
[4] [5] [6] state that the metabolite Monoacetylmorphine makes heroin a different drug that probably binds on a different receptor subtype, but this is wrong. "Heroin" is just a more rapid-acting form of morphine.[7]
Codeine, morphine and heroin metabolites are so similar, that it is impossible to distinguish whether heroin, codeine or morphine has been taken when low concentrations of opioids are found in the urine.[8]
The alkaloids
Morphine
Morphine is by far the most prevalent and important alkaloid in opium, consisting of anywhere from 10% to 16% of the total, and is responsible for most of its harmful effects such as lung edema, respiratory difficulties, coma, or cardiac or respiratory collapse, with a normal lethal dose of 120 to 250 mg.[9] (approximately two grams of opium.[10]) Despite morphine being the most medically significant alkaloid, larger quantities of the milder codeine—most of it manufactured from morphine—are consumed medically.
The expression of the morphine content of opium as a percentage depends in part on the moisture content. When the government purchases the opium as soon as practicable after it is collected, the moisture content is then usually about 30%. Commercial opium usually has around 10 to 15% moisture. Opium apparently dried at ordinary temperatures still retains considerable moisture—usually about six percent—which can be driven off at about 103 degrees Celsius.
The quantity of morphine produced by poppy plants in the form of opium depends on two factors: the percentage of morphine in the opium, and the quantity of opium produced. The latter factor in turn depends in part on whether each capsule is bled several times, or just once. In Turkey, Bulgaria, Greece and the Balkans, each capsule is bled only once, but in most other opium-producing countries, like Iran, India, and Afghanistan, the capsules are incised repeatedly, often four or five times on different days, until they will yield no more latex. The quantity of latex falls off rapidly with later incisions, and so does the morphine content.[11] Usually, all the opium obtained is mixed together. This is probably the chief reason for the often lower morphine content of Iranian and Indian opiums as compared with Turkish and Balkan opiums, although it must also be recognized that there are low-yielding and high-yielding strains of the poppy, one or the other of which may predominate in a given region.
Samples of opium assaying some 15% morphine from Japan, Indochina and Afghanistan, as well as from Turkey, Greece and the Balkans have been examined by the Secretariat. Afghanistan at one time exported two grades of opium, one of about 15% morphine and the other about 10%. The morphine content of dry capsule-chaff is about 0.25% to 0.5%, when not washed out by rain. Here again there are low-yielding and high-yielding varieties, but proper agricultural selection of poppies for morphine production means taking into account not only the percentage yield of morphine, but also the total weight of capsule-chaff produced per hectare, the poppy seed production per hectare, and other factors.
Most of the licit morphine is used to manufacture codeine through O-methylation. Morphine is also used to manufacture other drugs like apomorphine (not subject to the conventions), dihydromorphine, hydromorphone and many others. Through acetylation (in the form of the pro-drug—"heroin"), morphine becomes more lipid soluble, and thus, the morphine enters the brain more rapidly.[1]
Codeine
The codeine content of opium is related inversely to the morphine content but only in a general way. Codeine yield is closely related to the type of opium produced in a given district or even in some cases in an entire country. The opiums of the principal exporting countries have approximately the following percentages of codeine: Balkans 1.25%; Turkey 1.25%; Iran 3.4%; India 3.0%.
The highest percentages of codeine obtained by the Secretariat (averaging about 4.3%) were found in opium samples which came from north-eastern Asia (Korea, northern China).
The manufacturers’ statistics do not ordinarily show all the codeine obtained from opium. Some of it co-precipitates with the morphine, and there is no necessity of purifying the morphine completely of its codeine content, especially if it is to be used to manufacture more codeine.
Codeine is used to manufacture dihydrocodeine, hydrocodone, and others. It may also be used to manufacture the drugs ordinarily made by conversion of thebaine.[2]
Thebaine and Papaverine
The United Nations Secretariat is currently engaged in a survey, the most extensive ever attempted in this field, of opium samples from different regions for their thebaine and papaverine percentages. As yet, it is premature for general conclusions. However, the highest thebaine percentages found (nearly 5%) were in some samples from Indochina, which at the same time had virtually no papaverine. Both thebaine and papaverine have been high in most Iranian samples run. Papaverine is low in some Afghan and Indian opiums.
Thebaine is the most poisonous opium alkaloid and is scarcely used medically. It is even omitted from some of the preparations of mixed opium alkaloids which are used as soluble substitutes for opium. However, it is converted into several other narcotics which have medical use: hydrocodone, acetyldihydrocodeine, oxycodone, and the highly potent and powerful narcotic, oxymorphone.
Papaverine has a considerable medical use, so much so that supplies available from opium have sometimes run short. It is then manufactured synthetically.[3]
Terminology
''Opiate'' has traditionally referred to not only the alkaloids in opium, but also natural and semi-synthetic derivatives of morphine (itself an opiate). The term is often incorrectly used to refer to all drugs with opium- or morphine-like pharmacological action, which are more properly classified under the broader term ''opioid''.
References
1. http://www.u.arizona.edu/~tommyb/Opiates.html
2. http://jpet.aspetjournals.org/cgi/content/abstract/129/2/144
3. http://jpet.aspetjournals.org/cgi/content/full/299/2/760?ck=nck
4. http://www.nida.nih.gov/DirReports/DirRep297/DirectorReport1.html
5. http://opioids.com/6-monoacetylmorphine/index.html
6. http://www.ricercaitaliana.it/prin/dettaglio_completo_prin_en-2004052391.htm
7. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2420426&dopt=Abstract
8. http://preventiontraining.samhsa.gov/CMHC01/MOD8PM.htm
9. Mallinckrodt MSDS
10. Narcotic Drugs Anil Aggrawal
11. Annett, Harold Edward, "Factors Influencing Alkaloidal Content and Yield of Latex in the Opium Poppy (Papaver somniferum)". Biochemical Journal, 14, 618–36 (1920).
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