Articles: opioid-analgesics.
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Cahiers d'anesthésiologie · Jan 1991
Review[Opioids by the perimedullary route: mechanisms of opioid analgesia].
The identification of multiple opioid receptors and opioid peptides in the 1970 was the starting point of an increasing knowledge on opioid physiology and pharmacology. The mechanisms of action of spinally supraspinal levels. At the spinal level, opioids act by a modulation of specific supraspinal effect is the consequence of the migration of opioids, other in the bloodstream or in the cerebrospinal fluid, towards the encephalon. ⋯ At the receptor level, opioid agonists act, hypothetically via the system of adenylcylase, more certainly via a modulation of membrane tonic channels. Thus, opioids modify sodium, calcium and potassium currents, and modify the successives phases of the membrane action potential. The result is an hyperpolarization which is responsible of an inhibition of the release of various neurotransmitters such as P substance.
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Narcotics are used in neuro-anesthesiology according to their pharmacology and their effects on cerebral physiology. New narcotics (fentanyl, sufentanil, alfentanil) fulfill the requirements of modern neurosurgical anesthesiology looking for quick awakening.
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The patterns of recovery of patients who received seven different analgesic and sedative treatments were investigated with regard to the time at which the subjects awoke. For observations of the neurologic status, we developed a special score. ⋯ Piritramid/promethazine, pethidine/flunitrazepam, pethidine/promethazine and tramadol/methohexital required more time for awakening. On the basis of these results, we prefer to use the combination of fentanyl/midazolam, alfentanil/midazolam and ketamine/flunitrazepam to judge all patients' neurologic scores.
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Anaesthesiol Reanim · Jan 1991
ReviewPain control with intrathecally and peridurally administered opioids and other drugs.
Sharp pain is conducted rapidly by myelinated delta A fibers and diffused pain slowly by nonmyelinated C fibers to pseudobipolar neurons in the posterior ganglion and from there to neurons located in the posterolateral horn of the spinal cord. From here on nociferous impulses are transmitted by excitatory peptides (e.g. substance P) or amino acids (e.g. glutamate, aspartate) through interconnecting neurons of the pain pathways, primarily on the contralateral side, to the brain stem and from there to the sensory cortex, where they are appreciated and acted upon. There are specific inhibitory receptors located on axon terminals, near to the release sites of the excitatory amino acids and peptides. ⋯ Several different approaches are being investigated for the production of selective spinal analgesia without side effects. They include: a. the use of more lipophilic, long-lasting opioids (e.g. lofentanil) which would be almost completely absorbed by the spinal cord and therefore would not reach the medullary centers; b. the development of opioids with specific affinity to kappa- and for delta- and little or no affinity to mu-receptors, primarily responsible for side effects; and c. combining lower doses of opioid agonists with alpha 2-adrenergic agonists (e.g. clonidine) or with somatostatin. It is conceivable that in the not-too-distant future, it will be possible to achieve through these measures, selective spinal analgesia without side effects.