Interaction of Intrathecal Morphine with Bupivacaine and Lidocaine in the Rat

摘要: The interaction in the rat between intrathecal morphine and local anesthetics (bupivacaine lidocaine) on nociception (52.5 degrees C hot plate paw pressure), motor function, autonomic function (blood pressure [BP] heart rate [HR]) was examined over a range of doses for both anesthetics. High bupivacaine (75 micrograms) or lidocaine (500 produced block hypotension (150 micrograms bupivacaine) lasting approximately 15 7 min, respectively, whereas low (25 (100 only transient weakness 2 min less. Alone, neither agent altered response at doses, times, where agents had no effect upon function. In contrast, dose either anesthetic, after resolution weakness, these resulted significant leftward shift dose-response curves pressure, as measured by maximum observed peak area under time-effect curve. Thus, example, ED50 (95% confidence intervals) morphine/saline 1.7 (0.7-1.9) 1.1 (0.8-1.4) versus morphine/bupivacaine micrograms): 0.25 (0.21-0.42) 0.28 (0.2-0.4). Intrathecal not to have any dose-dependent effects blockade. Comparable results were also with found spinal cord clearance). We conclude that bupivacaine, which alone antinociceptive effect, times when clearly unimpaired, are able significantly augment activity tests. This prominent selective potentiation appears occur via non-pharmacokinetic mechanism probably reflects concentrations systems dorsal horn process acute high threshold afferent input.