|Mitragyna speciosa, กระท่อม (Thai), ketum, kratom or kratum
mitragyna speciosa (also known as kratom) is a tropical tree of the coffee family indigenous to south east asia. the leaves of m. speciosa contain various psychoactive alkaloids that produce mild stimulant and opioid effects. the pharmacology of kratom is complex, although it produces its major effects through action at opioid receptors in the brain.
m. speciosa is indigenous to thailand, indonesia, malaysia, myanmar, and papua new guinea, where it has been used in traditional medicines for centuries. traditionally, fresh or dried kratom leaves are chewed or made into tea. starting in the 2000s, kratom began to receive significant attention due to increased use in western cultures as an alternative medicine. it is readily available for purchase from a large number of internet vendors, most commonly as dried and powdered leaves.
user reports indicate that the effects of kratom vary depending on the dose used. lower doses are reported to produce a caffeine-like stimulant effect. higher doses produce opioid effects like pain relief, sedation, and euphoria. many users claim kratom is useful in treating opioid addiction as a weaning agent, particularly during the initial withdrawal phase. kratom exists in a variety of strains with different characteristics, some more opioid-like than others.
kratom’s mood-elevating effects have raised concerns about the plant’s potential for dependence and abuse. in some jurisdictions, its sale and importation have been restricted, and several public health authorities have raised alerts. strong evidence for its claimed benefits are lacking. it is highly advised to use harm reduction practices if using this substance.
the leaves of m. speciosa contain more than 40 compounds, including many indole alkaloids such as mitragynine, mitraphylline, and 7-hydroxymitragynine (which is currently the most likely candidate for the primary active chemical in the plant). other active compounds in m. speciosa include raubasine, rhynchophylline, and corynantheidine, among many others.
the amount of active alkaloids in the leaves highly depends on many factors. one major factor is the location of the tree. when trees are grown in southeast asia, the levels tend to be higher but when grown elsewhere (even in greenhouses) the levels tend to be low or non-existent. one analysis of products marketed as kratom leaf found mitragynine at levels of 1–6% and 7-hydroxymitragynine at levels of 0.01–0.04%.
kratom behaves as an opioid receptor agonist similar in function to morphine and other opiates, although its pharmacological action and subjective effects differ significantly from those of traditional opiates.
opioids exert their effects by binding to and activating the opioid receptors. they structurally mimic endogenous endorphins which are naturally found within the body and also work upon the opioid receptor system. the way in which opioids structurally mimic these natural endorphins results in their euphoric, pain-relieving and anxiolytic effects. this is because endorphins are responsible for reducing pain, causing sedation, and feelings of pleasure. they can be released in response to pain, strenuous exercise, orgasm, or general excitement.
mitragynine and 7-hydroxymitragynine bind as partial agonists to the μ-opioid receptors and antagonistic to the κ- and δ-opioid receptors. they have high binding affinities to the µ- and κ-receptors. the binding affinity to the δ-receptors is high for 7-hydroxymitragynine, but weak for mitragynine.
unlike most other opioids, kratom also presents affinity for the norepinephrine and serotonin receptor systems where it functions as an agonist. its action on norepinephrine and serotonin also likely contributes to kratom’s stimulating properties.
additionally, kratom contains alkaloids (rhynchophylline and mitraphylline) which function as nmda receptor antagonists. this may be responsible for the mild dissociating effects which occur at heavy doses.