Possible Interaction: 5-Hydroxytryptophan and Morphine

“The decrement in analgesic activity of morphine was reversed by pretreatment with 5-hydroxytryptophan.”

“GABA-stimulating agents (muscimol, depakine, aminohydroxyacetic acid), serotonin stimulants 5-hydroxytryptophan , fluoxetine), catecholaminergic stimulants (L-DOPA, apomorphine) and a cholinergic inhibitor (hemicholinium-3) of the brain were found to enhance the inhibitory effect of morphine and pentapeptide FK 33-824 on the cortical excitability of free-moving cats.”

“The combination of fluoxetine and 5-hydroxytryptophan (FLX/5-HTP) caused an initial increase in prolactin … with plasma values returning to basal levels by 4 h. When rats were pretreated with FLX/5-HTP instead of morphine, the prolactin … to an injection of morphine 4 h later … not attenuated.”

“ Morphine analgesia in mice was significantly potentiated by pretreatment with 5-hydroxytryptophan (5-HTP), especially with higher dose of morphine.”

“Accordingly, meperidine but not morphine potentiated the hyperpyrexia induced by the 5-HT precursor, 5-hydroxytryptophan.”

“2) Five-hydroxytryptophane , 5-hydroxytryptamine, tryptamine, amphetamine, mescaline and epinephrine prolong and enhance morphine analgesia whereas iproniazid and choline-p-tolyl-ether fail to do so. (”