Opioids Crude opium

Diarrhea from almost any cause can be controlled with the opioid analgesics, but if diarrhea is associated with infection such use must not substitute for appropriate chemotherapy. Crude opium preparations (eg, paregoric) were used in the past to control diarrhea, but now synthetic surrogates with more selective gastrointestinal effects and few or no CNS effects, eg, diphenoxylate or loperamide, are used. Several preparations are available specifically for this purpose (see Chapter 62). 

Papaver somniferum (opium poppy) contains a variety of opioid and related alkaloids, including codeine, morphine, noscapine, papaverine, and thebaine. Crude opium is the air-dried latex obtained by incising the unripe capsules of P. somniferum. Paregoric is ammoniated tincture of opium (Scotch paregoric) or camphorated tincture of opium (English paregoric). The use of these formulations has largely been replaced by use of the purified compounds. 

Opium is the dried exudate of the unripe capsule of Papaver somniferum.4 Varieties of this plant have been cultivated and used for several millennia. Today, it is grown in Turkey, Iran, Afghanistan, Russia, China, Southeast Asia, and Mexico, as well as in other areas of the world, both licitly and illicitly. Crude opium is known to contain over 25 different alkaloids that can be chemically divided into two categories the phenanthrenes and the ben-zylisoquinolines (Fig. 5-7). Only morphine, codeine, papaverine, and nascopine are of clinical interest thebaine is used as a starting compound for some semisynthetic opioids.5... 

Opium, obtained from the unripened seed pods of opium poppies, contains at least 20 different compounds. Chemically, they are alkaloids—organic compounds that contain nitrogen, are bases, and are produced by plants. About 10% of crude opium is morphine, which is primarily responsible for the effects of opium. Morphine is medically valuable as a strong painkiller able to produce sedation and loss of consciousness. The term opioid is now applied to all compounds with morphine-like activity. 

The prototypical opioid is morphine (A.137) (Figure A.39). Isolated in a crude form, called opium, morphine has been recognized as a potent pain killer for thousands of years. Although effective, morphine has a low oral availability (F = 25%). Two common derivatives of morphine include hydrocodone (Vicodin, A.138) and oxycodone (A.139), both of which have oral availabilities of greater than 75%. Oxycodone is often sold in an oral continuous-release form under the trade name of OxyContin. Not all opioids are semisynthetic derivatives of morphine. Dextropropoxyphene (Darvon, A.140) and tramadol (Tramal, A.141) are fully synthetic opioids. Both compounds preserve the pharmacophore of morphine as described in the morphine rule (see Chapter 11). Dextropropoxyphene and tramadol are depicted in Figure A.39 to highlight possible pharmacologically active conformations that resemble morphine. 

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