Side Effects of Central Analgesic Drugs

Morphine, as the prototype of a central analgesic drag, has characteristic adverse effects that are relevant to the treatment of patients. Important among these effects are the following  

Since the ratio between therapeutic effect and adverse effects varies among opioids, great effort has been made to synthesize compounds with a better ratio of antinociceptive activity versus adverse side effects. This effort to discover better, safer compounds necessitated the development of laboratory methods that are sensitive to and, therefore, could be used to quantify the adverse effects of opioids. Moreover, the discovery of several distinct types of receptors that can interact with opioids or with endogenous peptides 

Contributed by Charles P. France, Ph.D., on the basis of Chapter H.1.3 Side effects of central analgesic drugs in the book Drug Discovery and Evaluation - Pharmacological Assays , second Edition, Springer Verlag 2002. 

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Chapter I.J Side Effects of Central Analgesic Drugs... 

Opioids are compounds that bind one or more of the many different opioid receptors in the body. Opioids act primarily on the central nervous system. The selectivity of a given opioid for the various opioid receptors determines its characteristic activity. While many opioids are powerful analgesics, opioids often cause physical dependence and have tolerance issues. Sedation and decreased rate of breathing are also side effects associated with opioids. Despite their problems, opioids are generally the drug of choice for treating severe, acute pain. 

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