Kratom
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| Mitragyna speciosa Korth. |
Kratom (Mitragyna speciosa) is a medicinal leaf harvested from a large tree native to Southeast Asia in the Rubiaceae, first documented by Dutch colonial botanist Korthals. It is botanically related to the Corynanthe, Cinchona and Uncaria genii and shares some similar biochemistry. It is in the same family as coffee, and the psychoactive plant Psychotria viridis. Other species in the Mitragyna genus are used medicinally in Africa, and also used for their wood.
It is a well established psychoactive drug in its native region and there is some use elsewhere in the world. In Southeast Asia the fresh leaves are usually chewed, often continuously, by workers or manual laborers seeking a numbing, stimulating effect. Elsewhere, the leaves are often made into a tea or extracted into water and then evaporated into a tar that can be swallowed. Kratom is not often smoked, although this method does provide some effect.
Kratom contains many alkaloids including mitragynine, once thought to be the primary active, and 7-hydroxymitragynine, (7-OHM) which is currently the most likely candidate for the primary active chemical in the plant. Although structurally related to yohimbine and tryptamines, its pharmacology is quite different, acting as a potent mu-opioid receptor agonist. (7-hydroxymitragynine has antinociceptive effects with 17X the potency of morphine due entirely to its action on opioid receptors.) [1] Anectotal evidence supports that it may have some stimulant properties similar to yohimbine. Kratom users have described feeling alternatively stimulated then sedated over the course of several hours of use. Kratom also contains alkaloids found in uña de gato, which are powerful immune system enhancers and lower blood pressure, as well as epicatechin, a powerful antioxidant found in dark chocolate and closely related to the EGCG that gives green tea its beneficial effects. Other active chemicals in kratom include raubasine (best known from Rauwolfia serpentina) and some yohimbe alkakoids such as corynantheidine.
Kratom has many potential medicinal uses, including as a safer and cheaper replacement for methadone, and as a source of chemicals with a wide range of beneficial activities.
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[edit] Effects
Kratom's pharmacology shares some elements of the activity of other substances including opiates and yohimbine. The comparison to opiates is valid at doses high enough to produce these effects. Kratom has the ability to alleviate withdrawal in people dependent on opiates owing to the mu receptor agonism of mitragynine and 7-hydroxymitragynine. Kratom may cause constipation at these doses. It produces analgesia similar to weaker opiates such as codeine. Kratom also has a yohimbe-like stimulant activity, and uncaria-like immunostimulant activity. Kratom's effects are reported to be relatively short-lived, typically fading after two hours or less.
[edit] Addiction and Habituation
Kratom use is potentially habit-forming, and people who abuse it continuously may experience withdrawals upon cessation. Ethnological researchers conducting a surver of long-time kratom users in Southeast Asia reported a belief that users may develop dark patches of skin discoloration on their cheeks, however there seems no actual documentation of this occuring. No long term human studies have been done, so any assessment of long term consequences of kratom must be extrapolated from animal studies and the few reports from anthropologists.
The potential addictiveness of kratom's primary active component, 7-hydroxymitragynine has been demonstrated in a study by Matsumoto et al. [2] In an animal model, this study demonstrated tolerance, cross-tolerance with morphine, and naloxone-precipitated withdrawal from 7-hydroxymitragynine. The withdrawal symptoms were nearly identical to those from morphine, indicating that the drug might produce dependence in humans similar to other opiates. Anecdotal evidence would seem to lend credence to this theory; however, no human research has been done and many of those people reporting addiction are using kratom either as a home remedy for opiate addiction or in conjunction with an ongoing opiate dependence, which makes scientifically definitive claims impossible at this time.
[edit] Minor Alkaloids
It is interesting to note that whole Mitragyna speciosa leaf also contains a partial mu-opioid agonist (9-hydroxycorynantheidine), and a mu-opioid antagonist (corynantheidine). [3] The combination of a full agonist (such as 7-OHM and mitragynine) with an antagonist or partial agonist may be compared to the use of partial opioid-agonists to interrupt opiate addiction. Buprenorphine is one such example of a partial agonist/antagonist that is FDA approved to treat addiciton. It may be that ingesting whole kratom does not have the same addictive potential as 7-OHM alone.
Furthermore, kratom contains at least one alkaloid (rhynchophylline) that is a calcium channel blocker, and reduces NMDA-induced current. There is considerable research as to the role of NMDA receptor activity in the formation of dependence, and the symptoms of withdrawal. In 2005, Inturrisi demonstrated that co-administration of d-methadone (the isomer that lacks opioid activity, but is an NMDA antagonist) in small doses with morphine prevented the development of morphine tolerance in rats. [4] There is clinical evidence that administering low doses of NMDA antagonists, such as dextromethorphan can even partially alleviate symptoms of withdrawal, though the threshold for unwanted PCP-like effects in opiate-dependent patients is low. The presence of rhynchophylline in kratom should be investigated in order to determine its potential to modify the development of dependence.
[edit] Legal Status
Kratom is classified as an illegal Narcotic Level 5 drug in Thailand, but is still sold openly in markets in the rural south of the country. It is apparently legal in all other countries aside from Australia, Cambodia, Malaysia, and Myanmar (Burma). Thailand is rumored to be considering altering its legal status in light of recent discoveries of kratom's medicinal uses in treating drug addiction and as a possible safer natural alternative to illegal illicitly produced amphetamines. Similar research is also underway in Malaysia. Kratom is currently legal everywhere in the United States (the recently passed bill in Louisiana banning several entheobotanicals does not mention and/or include Kratom). It may be legally sold and taken in the UK.
