7-Hydroxymitragynine (mitragynine hydroxyindolenine) is a terpenoid indole alkaloid in the plant Mitragyna speciosa, commonly known as Kratom. It has opioid agonistic activity. “The potency, calculated using pD (2) values, was 30-fold higher than that of mitragynine and 17-fold higher than that of morphine, respectively. Antagonism of naloxone on concentration-response curves for 7-hydroxymitragynine confirmed its opioid effect. These results suggest that the opioid effect of M. speciosa is mostly based on the activity of 7-hydroxymitragynine.” One notable distinction between 7-hydroxymitragynine and traditional opioids is that 7-hydroxymitragynine does not cause hypoventilation (respiratory depression) and therefore does not carry the primary safety risk associated with traditional opioids. 7-Hydroxymitragynine is orally active in animals as an analgesic, and produces normal opioid side effects including constipation, though significantly less than morphine, development of tolerance and withdrawal syndrome upon abstinence. The O-acetyl ester (Acetoxy), 7-acetoxymitragynine has also been reported and found to be an active μ-opioid agonist.