Morphine-theophylline interaction: antagonism or facilitation?
1 Morphine-theophylline interactions were investigated in both acute and narcotic-dependent preparations, in vitro and in vivo, using four different experimental models: LD50 doses of morphine and naloxone in the mouse; naloxone-induced contractions in the electrically-stimulated and opiate-dependent isolated ileum of the guinea-pig; naloxone-induced jumps in the mouse; an calcium uptake in synaptosomal preparations. 2 The LD50 of morphine was significantly increased by theophylline. 3 The lethal effect of theophylline was potentiated by pretreatment of the animals with naloxone. 4 Theophylline displayed protective effects in the inhibitory response to morphine and antagonism to the withdrawal response induced by naloxone in the electrically-stimulated isolated ileum of the guinea-pig. 5 The number of jumps induced by naloxone in morphine-dependent mice was significantly diminished by theophylline. 6 The inhibitory effect of morphine on the synaptosomal uptake of calcium was decreased by theophylline. 7 The effects of both morphine and theophylline on the cyclic nucleotides and the possible role of calcium in these actions are discussed.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004347:Drug Interactions; D004558:Electric Stimulation; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D007928:Lethal Dose 50; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D013574:Synaptosomes / Q000378:metabolism; D013806:Theophylline / Q000494:pharmacology*
D009270:Naloxone; D009020:Morphine; D013806:Theophylline; D002118:Calcium