The term opiate is often incorrectly used to describe all drugs with opium- or morphine-like pharmacological action, which are more properly classified under the broader term opioid. Semi-synthetic opioids such as hydrocodone, hydromorphone, oxycodone, and oxymorphone, while derived from opiates, are not opiates themselves.
Opiates belong to the large biosynthetic group of benzylisoquinoline alkaloids, and are so named because they are naturally occurring alkaloids found in the opium poppy. The major psychoactive opiates are morphine, codeine, and thebaine. Papaverine, noscapine, and approximately 24 other alkaloids are also present in opium but have little to no effect on the human central nervous system, and as such are not considered to be opiates. Very small quantities of hydrocodone and hydromorphone are detected in assays of opium on rare occasions; it appears to be produced by the plant under circumstances and by processes which are not understood at this time and may include the action of bacteria. Dihydrocodeine, oxymorphol, oxycodone, oxymorphone, metopon and possibly other derivatives of morphine and/or hydromorphone also are found in trace amounts in opium.
Despite morphine's being the most medically significant alkaloid, larger quantities of the milder codeine — most of it manufactured from morphine — are consumed medically, as codeine has a greater and more predictable oral bioavailability than morphine, making it easier to titrate the dose.
While the full synthesis of opiates from naphthoquinone (Gates synthesis) or from other simple organic starting materials is possible, they are tedious and uneconomical processes. Therefore, most of the opiate-type analgesics in use today are either directly extracted from Papaver somniferum or synthesized from the natural opiates, mainly from thebaine.
Esters of morphine
There are several semi-synthetic opioids derived from the opiate morphine. Heroin (diacetylmorphine) is a morphine prodrug, meaning that it is metabolized by the body into morphine after administration. One of the major metabolites of heroin, 6-monoacetylmorphine (6-MAM), is also a morphine prodrug. Nicomorphine (morphine dinicotinate), dipropanoylmorphine (morphine dipropionate), desomorphine (di-hydro-desoxy-morphine), methyldesorphine, acetylpropionylmorphine, dibenzoylmorphine, diacetyldihydromorphine, and several others are also derived from morphine.
Opiate withdrawal syndrome effects are associated with the abrupt cessation or reduction of prolonged opiate usage.
In medical facilities such as hospitals and clinics, the threat of relapse is possible when Post-acute-withdrawal syndrome is under-emphasized to patients in transitional phases, especially with short-term buprenorphine, methadone or health facilities.
- This includes the substances morphine, codeine, and thebaine. "Opiate - Definitions from Dictionary.com". dictionary.reference.com. Retrieved 2008-07-04.
- Synthesis of morphine alkaloids Presentation School of Chemical Sciences, University of Illinois at Urbana-Champaign retrieved 12-02-2010
- "Esters of Morphine". United Nations Office on Drugs and Crime. http://www.unodc.org. Retrieved 10 March 2012.
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- World Health Organization guidelines for the availability and accessibility of controlled substances