Possible Interaction: Epinephrine and Morphine

“Multivariate analyses showed that noradrenaline (p = 0.029), but not adrenaline (p = 0.18), concentrations were significantly lower in the morphine group than the placebo group.”

“Preemptive analgesia using intraarticular bupivacaine and morphine with epinephrine resulted in lower pain scores during the 1st hour after an arthroscopic anterior cruciate ligament reconstruction than did preemptive treatment with bupivacaine and epinephrine or placebo and epinephrine.”

“Our data show that the addition of epinephrine enhances postoperative analgesia by intrathecal morphine without increasing the incidence of adverse effects as compared with intrathecal morphine alone. (”

“To investigate whether the addition of epinephrine would enhance postoperative pain relief by intrathecal morphine , we studied 36 patients scheduled to have spinal anesthesia for gynecologic surgery.”

“The addition of epinephrine to epidural morphine had significantly increased the quality and duration of analgesia.”

“Two suggested sources of this variability are prior use of epinephrine-containing solutions , which may enhance both analgesia and side effects of morphine , and prior use of 2-chloroprocaine, which may inhibit epidural morphine analgesia.”

“Compared with the plain morphine group, addition of epinephrine significantly decreased morphine concentrations in the azygos vein only at 5 and 10min after administration.”

“The admixture of epinephrine with epidural morphine increased the individual variation in the half life of morphine concentrations in the azygos vein.”

“Plasma morphine concentrations, measured in 12 patients, were lower, although not significantly so, in the adrenaline group and mean time to peak concentration markedly delayed.”

“The admixture of adrenaline with the extradural morphine increased the individual variability in CSF and plasma concentrations.”

“Following intracerebral administration of a minimal effective dose of adrenaline , a marked decrease of the analgesic ED_(50) of subcutaneous injection of morphine was noticed.”

“Such synergism and crosstolerance would suggest that the analgesic action of morphine might be related to that of adrenaline.”

“Combinations of epinephrine with methionine enkephalin or morphine increased the binding of both by about half a log unit.”