Effects of Kratom and Mitragynine

"The present study aimed to evaluate the safety (i.e. vital signs and adverse events) and impact on neurocognitive performance of single acute doses of mitragynine. Mitragynine did not have a significant effect on the majority of outcome measures at any dosage level and was well-tolerated. Still, the lowest dose (5 mg) increased subjective ratings of amphetamine-like arousal and attention. Further, the 5 mg dose increased accuracy in a sustained attention task and increased errors in the stop-signal task as compared to placebo. The highest dose (40 mg) of mitragynine increased subjective ratings of amnesia and produced some mild symptoms of psychological distress. Moreover, vital signs were not significantly affected by mitragynine, and only mild, transient side effects were reported."