Articles: opioid-analgesics.
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The aim of the regional administration of opioids is to provide an efficient and prolonged analgesia. Then, opiates can be useful for postoperative analgesia and for the treatment of chronic pain of malignant origin. Analgesia is correlated with several adverse effects of which the most frequent are nausea and itching and the most severe is respiratory depression. ⋯ Opioids also act by a reduction of the motor functions of the bowel, which perhaps could reduce the incidence of anastomotic breakdowns. Finally, other effects have been reported, as anecdotes, such as the treatment of spasm after bilateral replantation of the ureters, neurologic bladder dysfunctions and enuresis. Spinal administration of opioids has also been used as a treatment of premature ejaculation.
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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.
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Seven different schemes for analgesic anaesthesia were investigated for their clinical applicability, potential side effects, and impacts on circulation parameters of the systemic and pulmonary (peripheral) circulation as well as on the intracranial pressure. In all, so patients per group were treated. The results revealed different reactions of patients, such as a higher incidence of disturbances of the autonomic nervous system and excitation after medication withdrawal. ⋯ In several instances, a clear increase in the right atrial and the pulmonary arterial mean pressure as well as the intracranial pressure was observed during ketamine/flunitrazepam therapy. The combinations pethidine/promethazine or pethidine/flunitrazepam also showed clear side effects on the circulation and evoked an increase in the intracranial pressure. Fentanyl/midazolam or alfentanil/midazolam treatments were the most favourable combinations for most of the patients who were artificially respirated.
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Cahiers d'anesthésiologie · Jan 1991
Review[The use of opioids by the regional route in obstetrics].
Epidural and spinal administration of opioids in obstetrics can be used during labour and for cesarean section. Although these routes of administration are of limited use when opiates are employed as sole agents, the association with local anesthetics may improve the characteristics of analgesia. The administration of a local anesthetic-opiate mixture allows a reduction of the total amount of local anesthetics, thus reducing the incidence of maternal hypotension and the percentage of instrumental extraction. ⋯ Opioids may also be used for postoperative analgesia after cesarean section. Since they could be responsible for an opioid-related respiratory depression in the mother and the neonate, a strict supervision is absolutely necessary following this particular mode of administration of opiates. If human and technical means of supervision failed to bring into operation, it would be better not to use opioids by the spinal route in such a context.