Peripheral analgesic properties

Papaverine is an alkaloid of umipe poppies however, it is not related to compounds in the morphine class and does not possess analgesic properties. It is a peripheral vasodilator and has a direct effect on vessels. It causes dilation of coronary, cerebral, and pulmonary... 

Acetaminophen [a seat a MIN oh fen] and phenacetin [fe NASS e tin] act by inhibiting prostaglandin synthesis in the CNS. This explains their antipyretic and analgesic properties. They have less effect on cyclooxygenase in peripheral tissues, which accounts for their weak anti-inflammatory activity. Acetaminophen and phenacetin do not affect platelet function or increase blood clotting time, and they lack many of the side-effects of aspirin. [Note Phenacetin can no longer be prescribed in the United States because of its potential for renal toxicity. However, it is present in some proprietary preparations.]... 

Indomethacin has prominent antiinflammatory and analgesic-antipyretic properties similar to those of the salicylates. Indomethacin is a more potent inhibitor of the cyclooxygenases than is aspirin, but patient intolerance generally limits its use to short-term dosing. Indomethacin has analgesic properties distinct from its antiinflammatory effects, and there is evidence for central and peripheral actions. 

Morphine has hypotensive effects, increasing peripheral vascular capacity and decreasing blood pressure, which may be mediated through adenosine. For this reason, as well as its analgesic properties, intravenous morphine has been given for myocardial infarction, although it is not a part of the current standard of treatment. 

Its mechanism of action is not well understood, but probably resembles the central effects of clona-dine. Compared to clonadine, it binds more selectively to the over the ttj receptor and has approximately eight times the affinity. Like clonadine, it produces sedation, reduced salivation and initially raises and then significantly lowers the heart rate and blood pressure. This is probably due to the overall stimulation of both the central and peripheral pre- and postsynaptic ttj and ttj receptors. The a,-mediated hypotension and bradycardia may be pronounced with large doses or rapid infusions. It also has marked intrinsic anesthetic and analgesic properties that clonadine does not possess. This is probably due to the enhanced stimulation of central and spinal postsynaptic receptors as well as peripheral antinociception via... 

In some species, pharmacological effects other than muscle-relaxation may dominate. Thus, as already seen, the activity of S. erichsonii extracts appears to be due primarily to the presence of diaboline derivatives. Leaf extracts have analgesic properties, while stem-bark extracts have spasmolytic properties and augment the activity of the central nervous system (50). The bark alkaloids of S. glabra are reported to have central rather than peripheral effects (Table 1.4, footnote j). Sublethal doses of aqueous extracts from S. castelnaeana cause hypertension, tachycardia, and slight respiratory stimulation enhancement of the hypertension by atropine and its reduction by hexamethonium (mecamylamine) show that the extract has nicotinic activity. Evidently, the toxicity of the plant must be partly due to the tertiary bases it contains (314). 

Oxolamine [959-14-8] (57) is sold in Europe. It is an oxadiazole, and its general pharmacological profile is described (81). The compound possesses analgesic, antiinflammatory, local anesthetic, and antispasmodic properties, in addition to its antitussive activity. Although a central mechanism may account for some of the activity, peripheral inhibition of the cough reflex may be the dominant effect. The compound has been shown to be clinically effective, although it is less active than codeine (82,83). The synthesis of oxolamine is described (84). 

It is worth mentioning that iV-allylic substitution in a number of morphine derivatives, as a rule, leads to antagonistic properties. Naloxone is a few times stronger than nalorphine as an antagonist. It blocks opiate receptors. It eliminates central and peripheral action of opioids, including respiratory depression. Naloxone is used upon overdose of narcotic analgesics.Synonyms for this drug are narkan, talwin, and others. 

Acetaminophen differs from the nonsteroidal anti-inflammatory agents described in that it is devoid of anti-inflammatory and antirheumatic properties. It was recently shown that acetaminophen, like aspirin, inhibits cyclooxygenase action in the brain and is even stronger than aspirin. On the other hand, the mechanism of analgesic action of acetaminophen is not fully clear, since it acts poorly on peripheral cyclooxygenase. 

Non-steroidal antiinflammatory drugs (NSAIDs) are also known as nonopioid analgesics. They relieve pain without interacting with opioid receptors and do not depress CNS and have no drug dependence or drug abuse property and possess antipyretic activity also. They act primarily on peripheral pain mechanisms and also in CNS to raise pain threshold. 

Medicinally, cocaine is of value as a local anaesthetic for topical application. It is rapidly absorbed by mucous membranes and paralyses peripheral ends of sensory nerves. This is achieved by blocking ion channels in neural membranes. It was widely used in dentistry, but has been replaced by safer drugs, though it still has applications in ophthalmic and ear, nose, and throat surgery. As a constituent of Brompton s cocktail (cocaine and heroin in sweetened alcohol) it is available to control pain in terminal cancer patients. It increases the overall analgesic effect, and its additional CNS stimulant properties counteract the sedation normally associated with heroin (see page 332). 

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