Revista de la Sociedad Española del Dolor
versión impresa ISSN 1134-8046
A large number of opioid receptors are located in the substantia gelatinosa of the medullar dorsal horn. Epidurally injected opioids bind with these receptors in a competitive and saturable manner causing analgesia and a lower risk of side effects as compared with its parenteral administration. However, its possible side effects, mainly respiratory depression, should be considered. Morphine is the mu agonist opioid most widely used for acute and chronic pain, being regarded as the standard drug to which new analgesics are compared. Fentanyl is a phenyl-piperidine derived opioid agonist with a high affinity for mu receptors that results in an analgesic potency 50-100 times higher than morphine. Tramadol is the most recent synthetic opioid used in Spain; it has a low affinity for mu, kappa and delta receptors, and an analgesic potency 1/10 of parenteral and 1/30 of spinal morphine. Epidural opioids have been widely used in adults, much less so in children. In this article, the existing studies evaluating its effects in the paediatric age are reviewed, with a reference to pharmacokinetics, clinical considerations and possible side effects after the administration of epidural morphine, fentanyl or tramadol.
Palabras clave : opioids; epidural; paediatric.