Analgesia alkaloid

Opium is the milky exudate obtained by incising the unripe seed capsule of the poppy plant Papaver somniferum and morphine is the most important alkaloid of opium. Morphine produces analgesia through action in the brain and spinal cord, that contain peptides possessing opioid like pharmacological action. These endogenous substances are known as endogenous opioid peptides (earlier known as endorphin now known as P-endorphin). 

Opioid alkaloids (eg, morphine) produce analgesia through actions at receptors in the central nervous system (CNS) that contain peptides with opioid-like pharmacologic properties. The general term currently used for these endogenous substances is endogenous opioid peptides. 

Morphine, the natural alkaloid from which almost all opiate analgesics have been evolved, is stereospecific in the receptor interactions that are responsible for its opioid actions, namely, analgesia, depression of respiration, dependence liability, and GIT disturbances. Compounds with natural (-) and unnatural (+) geometry may exhibit antitussive actions. 

It was realized early that the morphine-related alkaloid thebaine, because of the conjugated diene in ring C, was the most chemically reactive of the opium alkaloids. A large variety of dienophiles readily underwent a Diels-Alder reaction with thebaine, affording several adduct compounds with opioid properties, including analgesia. 

Papaveretnm. Concentrated opium Omnopon Pantopon. A mixture of the hydrochlorides of the opium alkaloids in their approximate natural proportions. Contains approx 50% morphine, 3% oodeine, 20% noscapine, and S% papaverine. Exhibits biological action of morphine and other alkaloids present in opium. Clinical evaluation in intravenous analgesia I. A. Catling et aL, Brit. Med. J. 281, 478 (1980). 

Keywords Alkaloids Analgesia Codeine Demethylation Morphine Total synthesis... 

I. Pharmacology. Morphine is the principal alkaloid of opium and is a potent anal-gesio and sedative agent. In addition, it decreases venous tone and systemio vascular resistance, resulting in reduced preload and afterload. Morphine is variably absorbed from the gastrointestinal tract and is usually used parenterally. After intravenous injection, peak analgesia is attained within 20 minutes and usually lasts 3-5 hours. Morphine is eliminated by hepatic metabolism, with a serum half-life of about 3 hours however, the clearance of morphine is slowed, and duration of effect is prolonged in patients with renal failure. 

The primary modem use of the papaver alkaloids is for analgesia. Morphine is considered the classic example of a high-potency opioid. Opiates are medications derived from the poppy opioids, the more general term, refer to medications that work at the opioid receptors. All opiates are therefore opioids, but not all opioids are opiates. 

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