Herbal medicines for the management of opioid addiction: safe and effective alternatives to conventional pharmacotherapy?

Kratom: a primer for pain physicians

PURPOSE OF REVIEW

Kratom is used commonly in the United States, usually to mitigate pain, opioid withdrawal, or fatigue. A comprehensive discussion on kratom, tailored to pain management physicians, is needed, given its associated risks and potential interactions.

RECENT FINDINGS

Kratom and its main metabolites, mitragynine and 7-OH-mitragynine, bind to a variety of receptors including mu opioid receptors. Still, kratom cannot be described as a classic opioid. Kratom has been utilized without FDA approval as an alternative to traditional medications for opioid use disorder and opioid withdrawal. Lower doses of kratom typically cause opioid-like effects while higher doses can have sedating effects. Tolerance, dependence and withdrawal still occur, although kratom withdrawal appears to be more moderate than opioid withdrawal. Contamination with heavy metals and biological toxins is concerning and there is potential for serious complications, including seizures and death.

SUMMARY

The use of kratom as an opioid-sparing alternative as a part of a multimodal pain regimen is not without significant risks. It is of utmost importance for pain physicians to be aware of the risks and adverse effects associated with kratom use.

Endogenous Opioid Activity as the Mechanism of Action for Mitragyna speciosa (Kratom): The Current State of the Evidence

Kratom (Mitragyna speciosa) is a substance derived from botanical compounds native to Southeast Asia. This substance has been cultivated predominantly in Thailand, Malaysia, Vietnam, and Myanmar, where it has historically been used in traditional medicine as a near panacea for several health problems. Such ritualistic use of kratom has been present for centuries; however, recreational use appears to have increased globally, especially in the United States. Pharmacodynamic and pharmacokinetic studies have found that kratom demonstrates a unique parabolic, dose-dependent pattern of effects ranging from stimulation to opioid and analgesic effects. Pharmacological research indicates that kratom is both a mu opioid receptor (μ-OR; MOR) and a kappa opioid receptor (κ-OR; KOR) agonist, which mediates its analgesic effects. Other research suggests that kratom may simultaneously act on dopaminergic and serotonergic receptors, which mediate its stimulant effects. This chapter reviews the literature related to the structural, functional, and cultural characteristics of kratom use. We begin with an overview of current and historical patterns of kratom, followed by a review of data on the pharmacodynamics and pharmacokinetics of kratom thus far.

Kratom (Mitragyna speciosa) Validation: Quantitative Analysis of Indole and Oxindole Alkaloids Reveals Chemotypes of Plants and Products

Many consumers are turning to kratom (Mitragyna speciosa) to self-manage pain and opioid addiction. In the United States, an array of capsules, powders, and loose-leaf kratom products are readily available. Additionally, several online sites supply live kratom plants. A prerequisite to establishing quality control and quality assurance standards for the kratom industry, or understanding how alkaloid levels effect clinical outcomes, is the identification and quantitation of major and minor alkaloid constituents within available products and preparations. To this end, an ultra-high performance liquid chromatography-high resolution mass spectrometry method was developed for the analysis of 8 indole alkaloids (7-hydroxymitragynine, ajmalicine, paynantheine, mitragynine, speciogynine, isopaynantheine, speciociliatine, and mitraciliatine) and 6 oxindole alkaloids (isomitraphylline, isospeciofoleine, speciofoline, corynoxine A, corynoxeine, and rhynchophylline) in US-grown kratom plants and commercial products. These commercial products shared a qualitatively similar alkaloid profile, with 12 - 13 detected alkaloids and high levels of the indole alkaloid mitragynine (13.9 ± 1.1 - 270 ± 24 mg/g). The levels of the other major alkaloids (paynantheine, speciociliatine, speciogynine, mitraciliatine, and isopaynantheine) and the minor alkaloids varied in concentration from product to product. The alkaloid profile of US-grown M. speciosa "Rifat" showed high levels of the indole alkaloid speciogynine (7.94 ± 0.83 - 11.55 ± 0.18 mg/g) and quantifiable levels of isomitraphylline (0.943 ± 0.033 - 1.47 ± 0.18 mg/g). Notably, the alkaloid profile of a US-grown M. speciosa seedling was comparable to the commercial products with a high level of mitragynine (15.01 ± 0.20 mg/g). This work suggests that there are several M. speciosa chemotypes.

Thymol Nanopolymer Synthesis and Its Effects on Morphine Withdrawal Syndrome in Comparison With Clonidine in Rats

The drug delivery system is valuable in the treatment of the disease. A nanopolymer as a thymol and Thymbra spicata release system was synthesized and its effects on morphine withdrawal syndrome in comparison with clonidine in rats were studied. The nanopolymer was characterized by different methods, namely, IR, HNMR, CNMR, GPC, DLS, and AFM. Thymol in T. spicata extract was assessed. The loading and release rate of thymol and T. spicata extract on the nanopolymer were evaluated by HPLC. The median lethal dose (LD50) of the T. spicata extract, thymol, extract nanopolymer, and thymol nanopolymer was studied. The frequency of jumping, rearing, and teeth chattering in naloxone-induced morphine withdrawal syndrome was studied. Synthesized nanopolymer was desirable as a carrier for the drug. The loaded amount of extract and thymol on nanopolymer was estimated 55 ± 3.2% and 48 ± 2.6% and the drug released was 71 and 68%, respectively. LD50 of the T. spicata extract, thymol, extract nanopolymer, and thymol nanopolymer was 975, 580, 1,250, and 650 mg/kg, respectively. This study showed that thymol nanopolymer was more effective than clonidine to reduce the frequency of morphine withdrawal symptoms. Our results suggest that T. spicata extract, thymol, extract nanopolymer, and thymol nanopolymer are mighty in reducing the narcotic withdrawal signs. The mechanism of action and therapeutic potential is maybe similar to clonidine.

Understanding Kratom Use: A Guide for Healthcare Providers

Kratom (Mitragyna speciosa Korth., Rubiaceae) is a plant native to Southeast Asia, where it has been used for centuries as a mild stimulant and as medicine for various ailments. More recently, as kratom has gained popularity in the West, United States federal agencies have raised concerns over its safety leading to criminalization in some states and cities. Some of these safety concerns have echoed across media and broad-based health websites and, in the absence of clinical trials to test kratom’s efficacy and safety, considerable confusion has arisen among healthcare providers. There is, however, a growing literature of peer-reviewed science that can inform healthcare providers so that they are better equipped to discuss kratom use with consumers and people considering kratom use within the context of their overall health and safety, while recognizing that neither kratom nor any of its constituent substances or metabolites have been approved as safe and effective for any disease. An especially important gap in safety-related science is the use of kratom in combination with physiologically active substances and medicines. With these caveats in mind we provide a comprehensive overview of the available science on kratom that has the potential to i clarity for healthcare providers and patients. We conclude by making recommendations for best practices in working with people who use kratom.

Pentylenetetrazol-like stimulus is not produced following naloxone-precipitated mitragynine withdrawal in rats

RATIONALE

Kratom (Mitragyna speciosa Korth), a native medicinal plant of Southeast Asia, is proposed to exhibit potential therapeutic value as an opioid substitute. However, studies of its negative emotional states resulting from withdrawal particularly of its main psychoactive compound, mitragynine (MG), are limited.

OBJECTIVES

Using the pentylenetetrazol (PTZ) discrimination assay, this study aims to investigate the effects of MG in responding to the PTZ stimulus and to assess the generalisation effects of withdrawal from MG to the PTZ stimulus.

METHODS

Rats (n = 20) were trained on a tandem (FR-10, VI-15) schedule of food reinforcement to press one lever after administration of the anxiogenic compound PTZ (16 mg/kg, i.p.) and an alternate lever after vehicle. Following acute tests, training was suspended, and rats were chronically treated with MG or morphine at 8-h intervals for 9 days and withdrawal was precipitated on the tenth day using naloxone (1 mg/kg, i.p.). The rats were tested for generalisation to PTZ at 2, 8 and 24 h after the last dose of MG or morphine administration.

RESULTS

Unlike morphine that produced dose-related PTZ-like stimulus, MG at 3, 10, 30 and 45 mg/kg doses showed no substitution to the PTZ discriminative stimulus. In contrast to morphine which produced a time-dependent generalisation to the PTZ stimulus, naloxone did not precipitate withdrawal effects in MG-treated rats as they selected the vehicle lever at three withdrawal time points.

CONCLUSION

These results demonstrate that MG produces a very different response to morphine withdrawal that is not associated with anxiogenic-like subjective symptoms. These characteristics of MG may provide further support for use as a novel pharmacotherapeutic intervention for managing opioid use disorder.

Kratom-induced transaminitis with subsequent precipitated opioid withdrawal following naltrexone

Kratom is an herbal supplement that has gained popularity for recreational use within the United States. Kratom exerts opioid-like effects and, although not US FDA approved, is commonly used for self-treatment of pain, withdrawal management from opioids, and euphoria. Drug-related hepatic injury has been associated with kratom use. All of this raises concern for patient safety and monitoring. The potential for additive liver toxicity must be considered when kratom is used concurrently with hepatotoxic, over-the-counter, herbal, and prescription medications. This case report describes a case of kratom-induced liver inflammation complicated by opioid withdrawal that was precipitated by initiation of IM naltrexone. To our knowledge, there are no published case reports related to opioid withdrawal following naltrexone administration in patients using kratom (without other opioids). The purpose of this case report is to demonstrate potential complications that may arise with kratom use and considerations that should be taken prior to initiation of naltrexone in kratom users.

Oral Pharmacokinetics in Beagle Dogs of the Mitragynine Metabolite, 7-Hydroxymitragynine

BACKGROUND AND OBJECTIVES

7-Hydroxymitragynine (7-HMG) is an oxidative metabolite of mitragynine, the most abundant alkaloid in the leaves of Mitragyna speciosa (otherwise known as kratom). While mitragynine is a weak partial µ-opioid receptor (MOR) agonist, 7-HMG is a potent and full MOR agonist. It is produced from mitragynine by cytochrome P450 (CYP) 3A, a drug-metabolizing CYP isoform predominate in the liver that is also highly expressed in the intestine. Given the opioidergic potency of 7-HMG, a single oral dose pharmacokinetic and safety study of 7-HMG was performed in beagle dogs.

METHODS

Following a single oral dose (1 mg/kg) of 7-HMG, plasma samples were obtained from healthy female beagle dogs. Concentrations of 7-HMG were determined using ultra-performance liquid chromatography coupled with a tandem mass spectrometer (UPLC-MS/MS). Pharmacokinetic parameters were calculated using a model-independent non-compartmental analysis of plasma concentration-time data.

RESULTS

Absorption of 7-HMG was rapid, with a peak plasma concentration (C_max, 56.4 ± 1.6 ng/ml) observed within 15 min post-dose. In contrast, 7-HMG elimination was slow, exhibiting a mono-exponential distribution and mean elimination half-life of 3.6 ± 0.5 h. Oral dosing of 1 mg/kg 7-HMG was well tolerated with no observed adverse events or significant changes to clinical laboratory tests.

CONCLUSIONS

These results provide the first pharmacokinetic and safety data for 7-HMG in the dog and therefore contribute to the understanding of the putative pharmacologic role of 7-HMG resulting from an oral delivery of mitragynine from kratom.

The Right to Use Kratom from the Psychiatric and Islamic Perspectives

This paper aimed to summarize kratom's psychological effects on users and the Islamic views on kratom use. A literature survey of published kratom studies, teachings based on the holy Qur'an, the Sunnah, and views of several Islamic scholars based on qualitative methodology through text analysis was conducted. The results demonstrated that despite its beneficial therapeutic effects, the harm induced by kratom outweighs its benefits. We concluded that kratom use for medicinal purposes is only warranted if useful constituent mitragynine can be extracted and used on its own, and if more rigorous human studies demonstrated good safety profile and efficacy of mitragynine for therapeutic purposes.

Breakthrough Seizure Associated With Kratom Use in Patients With Epilepsy

PURPOSE OF REVIEW

Kratom (mitragynine) is a commercially available herbal supplement that is gaining popularity in the United States. Kratom is associated with a variety of neurologic effects. This review will discuss kratom's association with seizure through 3 cases and highlight what neurologists should know about kratom's clinical effects and legal status.

RECENT FINDINGS

Kratom is currently commercially available, unscheduled by the US Drug Enforcement Administration, and a topic of regulatory debate in the United States. Large poison center reviews have suggested that kratom use is associated with seizure. There have been limited case studies to corroborate this finding. We present 3 cases in which seizures were associated with kratom use in patients treated for epilepsy.

SUMMARY

Since 2008, kratom use is rising in prevalence in the United States aided by lack of regulation. Neurologists need to be aware of its association with seizure and other neurologic side effects.

The citrus flavanone naringenin prevents the development of morphine analgesic tolerance and conditioned place preference in male rats

BACKGROUND

Opioids are effective analgesics in the management of chronic pain. However, their clinical use is hindered by adverse side effects such as addiction and analgesic tolerance. Naringenin is a common polyphenolic constituent of the citrus fruits and is one of the most commonly consumed flavonoids within our regular diet. However, its influences on opioid tolerance and addiction have not yet been clarified.

OBJECTIVES

To examine the effect of different doses of naringenin on analgesic tolerance, conditioned place preference and neuroinflammation in morphine-exposed rats.

METHODS

Analgesic tolerance was induced by the injection of 10 mg/kg morphine twice daily for 8 days in 70 male Wistar rats. To evaluate the effect of naringenin on the development of morphine tolerance, different doses (10, 25 and 50 mg/kg i.p.) were injected 15 min before morphine. The tail-flick test was used to assess nociceptive threshold. Conditioned place preference test was used to evaluate morphine-seeking behaviors. The lumbar spinal cord was assayed to determine glial fibrillary acidic protein (GFAP) and cyclooxygenase-2 (COX-2) levels by Western blotting.

RESULTS

The data showed that naringenin could significantly prevent morphine tolerance (p < .001) and conditioned place preference. In addition, chronic morphine-induced GFAP and COX-2 overexpression was significantly reversed by 50 mg/kg naringenin (p < .05 and p < .01, respectively).

CONCLUSION

Our results suggest that naringenin may have a potential anti-tolerant/anti-addiction property against chronic morphine misuse and that this preventive effect is associated with its anti-neuroinflammatory effects.

Plants with Anti-Addictive Potential

Drug addiction is prevalent among individuals of modern society, being a major cause of disability and premature loss of life. Although the drug addiction have profound social, economical and health impact in the world population, its management remains a challenge as available pharmacological treatments remains ineffective for most people. The limited efficacy and adverse effects have led to a search for alternative therapies to treat drug addiction. In this context, natural products are an important source for new chemical substances with a potential therapeutic applicability. Therefore, this chapter will present data obtained after an extensive literature search regarding the use of medicinal plants as a pharmacological alternative for drug addiction treatment.

Temperature and pH-Dependent Stability of Mitragyna Alkaloids

Mitragynine (MG) is the principal psychoactive alkaloid in kratom. The drug produces a variety of dose-dependent effects that appeal to recreational drug users and individuals seeking therapeutic benefits in the absence of medical supervision. In light of documented intoxications, hospitalizations and fatalities, MG and other alkaloids from Mitragyna speciosa are of growing importance to the forensic toxicology community. However, the chemical stability of these compounds has not been thoroughly described. In this report, the stability of MG, 7-hydroxymitragynine (MG-OH), speciociliatine (SC), speciogynine (SG) and paynantheine (PY) are investigated. Short-term stability of the Mitragyna alkaloids was determined over a range of pH (2-10) and temperature (4-80°C) over 8 hours. Liquid chromatography--quadrupole/time-of-flight mass spectrometry was used to estimate half-lives and identify degradation products where possible. The stability of MG and other alkaloids was highly dependent on pH and temperature. All of the Mitragyna alkaloids studied were acid labile. Under alkaline conditions, MG undergoes chemical hydrolysis of the methyl ester to produce 16-carboxymitragynine. MG-OH was the most unstable alkaloid studied, with significant drug loss at 8 hours experienced at temperatures of 40°C and above. No significant drug losses were observed for MG in aqueous solution (pH 2-10) at 4, 20 or 40°C. Diastereoisomers of MG (SC and SG) demonstrated even greater stability. These findings are discussed within the context of the identification of Mitragyna alkaloids in toxicological specimens.

Pharmacologic and clinical assessment of kratom: An update

PURPOSE

This article presents updated information on kratom (Mitragyna speciosa), a natural opioid with stimulant properties that is currently sold in the United States without a prescription.

SUMMARY

Kratom exerts opioid and alpha-2 agonistic effects, as well as anti-inflammatory and mild stimulant effects. Respiratory depression has not been commonly reported, but kratom does cause a host of adverse effects. While kratom may have a role in patients who are in chronic pain or dependent on opioid painkillers or heroin, this needs to be established in clinical trials. Kratom may have drug interactions as both a cytochrome P-450 system substrate and inhibitor. Kratom does not appear in normal drug screens and, especially when ingested with other substances of abuse, may not be recognized as an agent of harm. There are numerous cases of death in kratom users, but many involved polypharmaceutical ingestions. There are assessments where people have been unable to stop using kratom therapy and withdrawal signs/symptoms occurred in patients or their newborn babies after kratom cessation. Both banning and failure to ban kratom places people at risk; a middle-ground alternative, placing it behind the pharmacy counter, might be useful.

CONCLUSION

Kratom has a unique pharmacologic profile that might offer advantages over other opioids, but its high abuse liability, potential for drug interactions and adverse events, and inadequate research into the balance of benefits to harm are concerning. There is mounting information on the adverse events associated with kratom use and potential treatments that can be useful to clinicians.

CYP450-Mediated Metabolism of Mitragynine and Investigation of Metabolites in Human Urine

Mitragyna speciosa (Kratom) has emerged as a recreational drug and a substance of medicinal intrigue. Although the drug was initially used recreationally for its sedating and euphoric effects, more recently its use has been associated with the non-medically supervised treatment of opioid abstinence syndrome. Mitragynine is the principal pharmacologically active alkaloid in kratom. Although metabolites of mitragynine have been identified, the cytochrome P450 (CYP450) enzymes responsible for its biotransformation are still under investigation. The goal of this study was to contribute further knowledge regarding CYP450 activity as it relates to mitragynine. Recombinant cytochrome P450 enzymes (rCYPs) were used to investigate the isoforms involved in its metabolism. Biotransformational products were identified using liquid chromatography-quadrupole/time of flight-mass spectrometry. Four rCYP enzymes (2C18, 2C19, 2D6 and 3A4) were found to contribute to the metabolism of mitragynine. 7-Hydroxymitragynine (which has an affinity for the mu-opioid receptor &gt;10-folds that of morphine) was produced exclusively by 3A4. 9-O-demethylmitragynine, the most abundant metabolite in vitro (and the most prevalent metabolite in urine among kratom users) was produced by 2C19, 3A4 and 2D6. 16-Carboxymitragynine was produced by rCYPs 2D6, 2C19 and 2C18. 2C19 was solely responsible for the formation of 9-O-demethyl-16-carboxymitragynine. In vitro rCYP studies were compared with phase I metabolites in urine from cases involving mitragynine.

DARK Classics in Chemical Neuroscience: Kratom

The psychoactive plant kratom is a native plant to Southeast Asia, and its major bioactive alkaloid is mitragynine. Mitragynine exerts its analgesic properties by acting on the opioid receptors. One of its active metabolites, 7-hydroxymytraginine, is found to be 40 times more potent than mitragynine and 10 times more potent than morphine. Interestingly, current research suggests that mitragynine behaves as an atypical opioid agonist, possessing analgesic activity with less severe side effects than those of typical opioids. Although Thailand and Malaysia have criminalized the use, possession, growing, or selling of kratom due to its abuse potential, kratom still remains unregulated in the United States. The U.S. Drug Enforcement Agency (DEA) listed kratom as a "drug of concern" in 2008 with the intent to temporarily place mitragynine and 7-hydroxymitragynine onto Schedule I of the Controlled Substances Act. However, responses from the general public, U.S. Congress, and Kratom Alliances had the DEA retract their intent. Kratom is currently marketed in the United States as a dietary or herbal supplement used to treat chronic pain, anxiety, and depression with over $207 million in annual sales in the United States alone. Here, we will review the traditional and medicinal uses of kratom along with the synthesis of its bioactive ingredients and their pharmacology, metabolism, and structure-activity relationships. The importance in society of this currently controversial substance will also be discussed.

Abuse liability and therapeutic potential of the Mitragyna speciosa (kratom) alkaloids mitragynine and 7-hydroxymitragynine

Kratom, derived from the plant Mitragyna speciosa, is receiving increased attention as an alternative to traditional opiates and as a replacement therapy for opiate dependence. Mitragynine (MG) and 7-hydroxymitragynine (7-HMG) are major psychoactive constituents of kratom. While MG and 7-HMG share behavioral and analgesic properties with morphine, their reinforcing effects have not been examined to date. 7-HMG, but not MG, substituted for morphine self-administration in a dose-dependent manner in the rat self-administration paradigm. Following the substitution procedure, re-assessment of morphine self-administration revealed a significant increase following 7-HMG and a significant decrease following MG substitution. In a separate cohort, 7-HMG, but not MG, engendered and maintained intravenous self-administration in a dose-dependent manner. The effects of pretreatment with nalxonaxine (NLXZ), a μ1 opiate receptor antagonist, and naltrindole (NTI), a δ opiate receptor antagonist, on 7-HMG and morphine self-administration were also examined. Both NLXZ and NTI reduced 7-HMG self-administration, whereas only NLXZ decreased morphine intake. The present results are the first to demonstrate that 7-HMG is readily self-administered, and the reinforcing effects of 7-HMG are mediated in part by μ and δ opiate receptors. In addition, prior exposure to 7-HMG increased subsequent morphine intake whereas prior exposure to MG decreased morphine intake. The present findings indicate that MG does not have abuse potential and reduces morphine intake, desired characteristics of candidate pharmacotherapies for opiate addiction and withdrawal, whereas 7-HMG should be considered a kratom constituent with high abuse potential that may also increase the intake of other opiates.

Kratom-Induced Cholestatic Liver Injury Mimicking Anti-Mitochondrial Antibody-Negative Primary Biliary Cholangitis: A Case Report and Review of Literature

Kratom is an herbal supplement used to relieve chronic pain or opioid withdrawal symptoms. Recent news articles covering adverse effects associated with kratom use have brought attention to its organ toxicities. Reports of kratom-induced hepatic toxicity are limited and only three case reports of kratom-induced liver injury with histopathologic examination of the liver biopsies are available. A 40-year-old female presented with symptoms of mixed cholestatic and hepatocellular liver injury without clear etiology. The laboratory and imaging workup suggested possibilities of autoimmune hepatitis, autoimmune hepatitis-primary biliary cholangitis (PBC) overlap syndrome, or drug-induced liver injury. Autoantibodies including anti-mitochondrial antibody (AMA) were negative. Liver biopsy showed granulomatous hepatitis with prominent duct injury, suggestive of AMA-negative PBC. She subsequently was referred to a hepatologist and a history of recent kratom use was finally revealed. Kratom was discontinued and the symptoms improved. Kratom-induced hepatic toxicity may manifest with variable biochemical and clinical abnormalities. Histologically, it may mimic AMA-negative PBC. Our case highlights the importance of thorough history taking, interdisciplinary approach and communication for optimal patient care.

Detection and Identification of Kratom (Mitragyna speciosa) and Marijuana (Cannabis sativa) by a Real-Time Polymerase Chain Reaction High-Resolution Melt Duplex Assay. J Forensic Sci 2019;65:52-60. [PMID: 31433500 DOI: 10.1111/1556-4029.14167]

Mitragyna speciosa (MS), a plant commonly known as kratom, is a widely used "legal high" opiate alternative for pain relief. DNA extracted from MS and 26 additional plant species was amplified by PCR using primers targeting the strictosidine beta-D-glucosidase (SGD) and secologanin synthase 2 (SLS2) genes and detected by high-resolution melt curves using three intercalating dyes. Amplicon sizes were confirmed using agarose gel electrophoresis. The observed melt temperatures for SGD and SLS2 were 77.08 ± 0.38°C and 77.61 ± 0.46°C, respectively, using SYBR^® Green I; 80.18 ± 0.27°C and 80.59 ± 0.08°C, respectively, using Radiant^™ Green; and 82.19 ± 0.04°C and 82.62 ± 0.13°C, respectively, using the LCGreen^® PLUS dye. The SLS2 primers demonstrated higher specificity and identified MS DNA at 0.05 ng/μL. In a duplex reaction, SLS2 and tetrahydrocannabinoic acid synthase gene primers detected and differentiated MS and Cannabis sativa (CS) by melt peaks at 82.63 ± 0.35°C and 85.58 ± 0.23°C, respectively, using LCGreen^® PLUS.

Kratom policy: The challenge of balancing therapeutic potential with public safety

Kratom (Mitragyna speciosa) is a tree-like plant indigenous to Southeast Asia. Its leaves, and the teas brewed from them have long been used by people in that region to stave off fatigue and to manage pain and opioid withdrawal. Evidence suggests kratom is being increasingly used by people in the United States and Europe for the self-management of opioid withdrawal and treatment of pain. Recent studies have confirmed that kratom and its chemical constituents have potentially useful pharmacological actions. However, there have also been increasing numbers of reports of adverse effects resulting from use of kratom products. In August 2016, the US Drug Enforcement Administration announced plans to classify kratom and its mitragynine constituents as Schedule I Controlled Substances, a move that triggered a massive response from pro-kratom advocates. The debate regarding the risks, and benefits and safety of kratom continues to intensify. Kratom proponents tout kratom as a safer and less addictive alternative to opioids for the management of pain and opioid addiction. The anti-kratom faction argues that kratom, itself, is a dangerous and addictive drug that ought to be banned. Given the widespread use of kratom and the extensive media attention it is receiving, it is important for physicians, scientists and policy makers to be knowledgeable about the subject. The purpose of this commentary is to update readers about recent developments and controversies in this rapidly evolving area. All of the authors are engaged in various aspects of kratom research and it is our intention to provide a fair and balanced overview that can form the basis for informed decisions on kratom policy. Our conclusions from these analyses are: (a) User reports and results of preclinical studies in animals strongly suggest that kratom and its main constituent alkaloid, mitragynine may have useful activity in alleviating pain and managing symptoms of opioid withdrawal, even though well-controlled clinical trials have yet to be done. (b) Even though kratom lacks many of the toxicities of classic opioids, there are legitimate concerns about the safety and lack of quality control of purported "kratom" products that are being sold in the US. (c) The issues regarding the safety and efficacy of kratom and its mitragynine constituent can only be resolved by additional research. Classification of the Mitragyna alkaloids as Schedule I controlled substances would substantially impede this important research on kratom.

Bifunctional opioid receptor ligands as novel analgesics

Prolonged treatment of chronic severe pain with opioid analgesics is frought with problematic adverse effects including tolerance, dependence, and life-threatening respiratory depression. Though these effects are mediated predominately through preferential activation of μ opioid peptide (μOP) receptors, there is an emerging appreciation that actions at κOP and δOP receptors contribute to the observed pharmacologic and behavioral profile of μOP receptor agonists and may be targeted simultaneously to afford improved analgesic effects. Recent developments have also identified the related nociceptin opioid peptide (NOP) receptor as a key modulator of the effects of μOP receptor signaling. We review here the available literature describing OP neurotransmitter systems and highlight recent drug and probe design strategies.

Mitragyna speciosa: Clinical, Toxicological Aspects and Analysis in Biological and Non-Biological Samples

The abuse of psychotropic substances is a well-known phenomenon, and many of them are usually associated with ancestral traditions and home remedies. This is the case of Mitragyna speciosa (kratom), a tropical tree used to improve work performance and to withstand great heat. According to several published studies, the main reasons for kratom consumption involve improving sexual performance and endurance, but also social and recreational uses for the feeling of happiness and euphoria; it is also used for medical purposes as a pain reliever, and in the treatment of diarrhea, fever, diabetes, and hypertension. However, this plant has gained more popularity amongst young people over the last years. Since it is available on the internet for purchase, its use is now widely as a drug of abuse, namely as a new psychoactive substance, being a cheaper alternative to opioids that does not require medical prescription in most countries. According to internet surveys by the European Monitoring Centre for Drugs and Drug Addiction in 2008 and 2011, kratom was one of the most widely supplied new psychoactive substances. The composition of kratom is complex; in fact, more than 40 different alkaloids have been identified in Mitragyna speciosa so far, the major constituent being mitragynine, which is exclusive to this plant. Besides mitragynine, alkaloids such as corynantheidine and 7-hydroxamitragynine also present pharmacological effects, a feature that may be attributed to the remaining constituents as well. The main goal of this review is not only to understand the origin, chemistry, consumption, and analytical methodologies for analysis and mechanism of action, but also the use of secondary metabolites of kratom as therapeutic drugs and the assessment of potential risks associated with its consumption, in order to aid health professionals, toxicologists, and police authorities in cases where this plant is present.

Attenuation of Morphine Withdrawal Syndrome by Prosopis Farcta Extract and Its Bioactive Component Luteolin in Comparison with Clonidine in Rats

Background

Today, the plant Prosopis farcta is frequently used for traditional medicinal purposes. The aim of this study was the identification of luteolin in P. farcta extract (PFE) and to evaluate its effect on morphine discontinuation syndrome in rats.

Material/Methods

Using high-performance liquid chromatography (HPCL), luteolin was evaluated in PFE. The frequency of behavioral symptoms of morphine withdrawal (jumping, rearing, and teeth chattering) induced by naloxone challenge were illustrated in morphine-dependent rats receiving PFE, luteolin, saline, or clonidine. LD50 of PFE and luteolin was 540 mg/kg and 150 mg/kg, respectively. Signs of behavioral morphine withdrawal in rats were significantly inhibited by chronic co-administration of PFE, luteolin, or clonidine with morphine.

Results

This study showed that PFE was less effective than clonidine at a dose of 100 mg/kg, and at doses of 200 mg/kg and 300 mg/kg it was comparable to clonidine, and did not show a significant difference in the reduction of morphine withdrawal symptoms. Luteolin was comparable in 30 mg/kg, 60 mg/kg, and 90 mg/kg with clonidine to reduce the frequency of morphine withdrawal symptoms. PFE can be used as a source of luteolin.

Conclusions

The study findings suggest that PFE and luteolin might reduce the signs of narcotic withdrawal. Due to a similar effect to clonidine, its mechanism of action might be through the protein kinase A pathway and might have human therapeutic potential.

Identification of five Mitragyna alkaloids in urine using liquid chromatography-quadrupole/time of flight mass spectrometry

Mitragyna speciosa (Kratom) is a psychoactive plant that has recently emerged as a recreational drug. Mitragyna alkaloids are not within the scope of traditional forensic toxicology screening methods, which may contribute to under-reporting. Solid phase extraction (SPE) and liquid chromatography-quadrupole/time of flight mass spectrometry (LC-Q/TOF-MS) were used to identify five alkaloids in urine. Target analytes included the two known psychoactive compounds, mitragynine and 7-hydroxymitragynine, in addition to speciociliatine, speciogynine, and paynantheine. Two deuterated internal standards (mitragynine-D₃ and 7-hydroxymitragynine-D₃) were employed. Using traditional reversed phase chromatography all compounds and isomers were separated in 10 min. The procedure was validated in accordance with the Scientific Working Group for Forensic Toxicology (SWGTOX) Standard Practices for Method Validation. Extraction efficiencies were 63-96% and limits of quantitation were 0.5-1 ng/mL. Precision, bias and matrix effects were all within acceptable thresholds, with the exception of 7-hydroxymitragynine, which is notably unstable and unsuitable for quantitative analysis. In this paper we present a simultaneous quantitative analytical method for mitragynine, speciociliatine, speciogynine and paynantheine, and a qualitative assay for 7-hydroxymitragynine in urine using high resolution mass spectrometry (HRMS).

Kratom use and mental health: A systematic review

BACKGROUND

Kratom (Mitragyna speciosa) is a psychoactive plant native to Southeastern Asia that is receiving increased international attention as a potential therapeutic agent. While much of the limited scientific research on kratom is focused on its analgesic potential, kratom use also has important risks and benefits in the domain of mental health.

METHODS

We conducted a comprehensive systematic review of all studies on kratom use and mental health published between January 1960 and July 2017.

RESULTS

Findings indicate kratom's potential as a harm reduction tool, most notably as a substitute for opioids among people who are addicted. Kratom also enhances mood and relieves anxiety among many users. For many, kratom's negative mental health effects - primarily withdrawal symptoms - appear to be mild relative to those of opioids. For some users, however, withdrawal is highly uncomfortable and maintaining abstinence becomes difficult.

CONCLUSION

Results inform clinicians working in the mental health and substance use fields, policy-makers, and researchers about the mental health effects of this plant.

The abuse potential of kratom according the 8 factors of the controlled substances act: implications for regulation and research

RATIONALE

Consideration by the US Drug Enforcement Administration and Food and Drug Administration of placing kratom into Schedule I of the Controlled Substances Act (CSA) requires its evaluation of abuse potential in the context of public health.

OBJECTIVE

The objective of the study is to provide a review of kratom abuse potential and its evaluation according to the 8 factors of the CSA.

RESULTS

Kratom leaves and extracts have been used for centuries in Southeast Asia and elsewhere to manage pain and other disorders and, by mid-twentieth century, to manage opioid withdrawal. Kratom has some opioid effects but low respiratory depression and abuse potential compared to opioids of abuse. This appears due to its non-opioid-derived and resembling molecular structure recently referred to as biased agonists. By the early 2000s, kratom was increasingly used in the US as a natural remedy to improve mood and quality of life and as substitutes for prescription and illicit opioids for managing pain and opioid withdrawal by people seeking abstinence from opioids. There has been no documented threat to public health that would appear to warrant emergency scheduling of the products and placement in Schedule I of the CSA carries risks of creating serious public health problems.

CONCLUSIONS

Although kratom appears to have pharmacological properties that support some level of scheduling, if it was an approved drug, placing it into Schedule I, thus banning it, risks creating public health problems that do not presently exist. Furthermore, appropriate regulation by FDA is vital to ensure appropriate and safe use.

Pharmacologic and clinical assessment of kratom

PURPOSE

This article reviews the pharmacology, clinical utility, adverse effects, and abuse potential of kratom.

SUMMARY

The leaves of Mitragyna speciosa contain the biologically active alkaloids of kratom. Kratom exerts opioid and α-2 receptor agonistic effects as well as antiinflammatory and parasympathetic-impeding effects. There are no published human pharmacologic, pharmacokinetic, or drug interaction studies on kratom or mitragynine, making it virtually impossible to fully understand kratom's therapeutic potential and risks and the populations most likely to benefit or experience harm from its use. Kratom has been used to ameliorate opioid withdrawal symptoms but also induces withdrawal. Human pharmacologic, pharmacokinetic, and clinical data are of low quality, precluding any firm conclusions regarding safety and efficacy. Respiratory depression has not been commonly reported, but kratom does cause a host of adverse effects without clear guidance for how they should be treated. There are numerous assessments where people have been unable to stop using kratom therapy, and withdrawal signs and symptoms are problematic. Kratom does not appear in normal drug screens and, when taken with other substances of abuse, may not be recognized. Thirty-six deaths have been attributed to kratom, and the Food and Drug Administration issued a public health warning about the substance in November 2017.

CONCLUSION

Kratom exerts opioid and α-2 receptor agonistic effects as well as antiinflammatory and parasympathetic-impeding effects. Human pharmacologic, pharmacokinetic, and clinical data are of low quality, precluding any firm conclusions regarding safety and efficacy.

Prevalence and motivations for kratom use in a sample of substance users enrolled in a residential treatment program

BACKGROUND

Kratom use in the West has increased recently, yet the prevalence and motives for use among individuals with a history of substance use disorder (SUD) have not been fully examined. Kratom has been documented as a means of treating chronic pain, mitigating drug dependence, and easing withdrawal symptoms, yet it is unclear if substance users are utilizing kratom as a self-medication. Abuse liability, side effects, and overall appeal of kratom remain uncertain.

METHODS

In April 2017, an anonymous survey regarding kratom use and motivations was completed by clients enrolled in a 12-Step-oriented residential program. 500 respondents with a self-reported history of SUD completed the survey.

RESULTS

20.8% of respondents endorsed lifetime kratom use and 10.2% reported past-12-month use. Kratom-users were younger (=32.1 vs. 35.9, p<0.001) and were more versatile substance users. A majority (68.9%) of kratom-users reported having used the drug as a means of reducing or abstaining from non-prescription opioids (NPO) and/or heroin, and 64.1% reported using kratom as a substitute for NPO/heroin. 18.4% of kratom-users reported using the drug due to a disability or chronic pain. One-third of kratom-users stated that kratom was a helpful substance and that they would try it again. However, kratom was not preferred and was indicated as having less appeal than NPO, heroin, amphetamines, and Suboxone.

CONCLUSIONS

Among substance users, kratom use may be initiated for a variety of reasons, including as a novel form of harm-reduction or drug substitution, particularly in the context of dependence and withdrawal from other substances.

Update on the Pharmacology and Legal Status of Kratom

Kratom (Mitragyna speciosa) is a plant indigenous to Southeast Asia. Its leaves and the teas brewed from them have long been used by people in that region to stave off fatigue and to manage pain and opioid withdrawal. In a comprehensive review published in 2012, Prozialeck et al presented evidence that kratom had been increasingly used for the self-management of opioid withdrawal and pain in the United States. At the time, kratom was classified as a legal herbal product by the US Drug Enforcement Administration. Recent studies have confirmed that kratom and its chemical constituents do have useful pharmacologic actions. However, there have also been increasing numbers of reports of adverse effects resulting from use of kratom products. In August 2016, the US Drug Enforcement Administration announced plans to classify kratom and its mitragynine constituents as Schedule 1 controlled substances, a move that triggered a massive response from kratom advocates. The purpose of this report is to highlight the current scientific and legal controversies regarding kratom.

New psychoactive substances of natural origin: A brief review

Plant-based drugs of abuse are as old as recorded human history. Although traditional addictive substances, such as opium, cannabis and coca, have been controlled by the United Nations anti-drug conventions, many, if not most, natural plants with addictive or abuse liability remain elusive. Therefore, the United Nations Office on Drugs and Crime (UNODC) has warned the emerging threat from new psychoactive substances (NPS), which are mostly derived or modified from the constituents of natural origin. For example, synthetic cannabinoids and synthetic cathinones are derived from the cannabis and khat plant, respectively. In this review, we briefly discussed the chemistry, pharmacology and toxicology of five common NPS of natural origin, i.e., khat, kratom, salvia, magic mushroom and mandrake. Through the review, we hope that professionals and general public alike can pay more attention to the potential problems caused by natural NPS, and suitable control measures will be taken.

The effects of kratom on restraint-stress-induced analgesia and its mechanisms of action

ETHNOPHARMACOLOGICAL RELEVANCE

Mitragyna speciosa and its extracts are called kratom (dried leaves, extract). They contain several alkaloids with an affinity for different opioid receptors. They are used in traditional medicine for the treatment of different diseases, as a substitute by opiate addicts, and to mitigate opioid withdrawal symptoms. Apart from their medical properties, they are used to enhance physical endurance and as a means of overcoming stress.

PURPOSE

The aim of this study was to determine the mechanisms underlying the effects of kratom on restraint-stress-induced analgesia which occurs during or following exposure to a stressful or fearful stimulus.

METHODS

To gain further insights into the action of kratom on stress, we conducted experiments using restraint stress as a test system and stress-induced analgesia as a test parameter. Using transgenic mu opioid-receptor (MOR) deficient mice, we studied the involvement of this receptor type. We used nor-binaltorphimine (BNT), an antagonist at kappa opioid receptors (KOR), to study functions of this type of receptor. Membrane potential assay was also employed to measure the intrinsic activity of kratom in comparison to U50,488, a highly selective kappa agonist.

RESULTS

Treatment with kratom diminished stress-induced analgesia in wildtype and MOR knockout animals. Pretreatment of MOR deficient mice with BNT resulted in similar effects. In comparison to U50,488, kratom exhibited negligible intrinsic activity at KOR alone.

CONCLUSIONS

The results suggest that the use of kratom as a pharmacological tool to mitigate withdrawal symptoms is related to its action on KOR.

A botanical, phytochemical and ethnomedicinal review of the genus Mitragyna korth: Implications for products sold as kratom

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Mitragyna (Rubiacaeae) has been traditionally used in parts of Africa, Asia and Oceania. In recent years, there has been increased interest in species of Mitragyna with the introduction of products to western markets and regulatory uncertainty.

AIM OF THE STUDY

This paper reviewed the traditional ethnomedicinal uses of leaves for species belonging to the genus Mitragyna with reference to the botany and known chemistry in order to highlight areas of interest for products currently being sold as kratom.

MATERIALS AND METHODS

A literature search was conducted using Web of Science, Google Scholar, the Royal Museum for Central Africa, Internet Archive, Hathi Trust, and Biodiversity Heritage Library search engines in the spring of 2015, fall of 2016 and winter of 2017 to document uses of bark, leaf and root material.

RESULTS

Leaves of M. speciosa (kratom) had the most common documented ethnomedicinal uses as an opium substitute or remedy for addiction. Other species of Mitragyna were reportedly used for treating pain, however the mode of preparation was most often cited as topical application. Other uses of Mitragyna included treatment of fever, skin infections, and as a mild anxiolytic.

CONCLUSIONS

Mitragyna species have been used medicinally in various parts of the world and that there is significant traditional evidence of use. Modern products that include formulations as topical application of liniments, balms or tinctures may provide effective alternatives for treatment of certain types of pains. Future research is required to establish safety and toxicology limits, medicinal chemistry parameters and the potential for different physiological responses among varying genetic populations to support regulatory requirements for Mitragyna spp.

Traditional Chinese Medicine (TCM) Therapy

Traditional Chinese Medicine(TCM) has been utilized in China for more than 2,000 years, and it has been practiced in treatment of substance addiction and non-substance addictions. TCM have efficacy in the rehabilitation of abnormal physical problems induced by chronic drug use, including improving immune function, increasing working memory, and protecting against neurological disorders. Given that TCM is potentially effective in the prevention of relapse, it has been suggested that TCM may be the ideal choice in the future for the treatment of opiate addiction. This review examines the significance of effective Chinese herbs and prescriptions for Drug Addiction, Alcohol addiction and food addiction.

Novel Psychoactive Substances-Recent Progress on Neuropharmacological Mechanisms of Action for Selected Drugs

A feature of human culture is that we can learn to consume chemical compounds, derived from natural plants or synthetic fabrication, for their psychoactive effects. These drugs change the mental state and/or the behavioral performance of an individual and can be instrumentalized for various purposes. After the emergence of a novel psychoactive substance (NPS) and a period of experimental consumption, personal and medical benefits and harm potential of the NPS can be estimated on evidence base. This may lead to a legal classification of the NPS, which may range from limited medical use, controlled availability up to a complete ban of the drug form publically accepted use. With these measures, however, a drug does not disappear, but frequently continues to be used, which eventually allows an even better estimate of the drug's properties. Thus, only in rare cases, there is a final verdict that is no more questioned. Instead, the view on a drug can change from tolerable to harmful but may also involve the new establishment of a desired medical application to a previously harmful drug. Here, we provide a summary review on a number of NPS for which the neuropharmacological evaluation has made important progress in recent years. They include mitragynine ("Kratom"), synthetic cannabinoids (e.g., "Spice"), dimethyltryptamine and novel serotonergic hallucinogens, the cathinones mephedrone and methylone, ketamine and novel dissociative drugs, γ-hydroxybutyrate, γ-butyrolactone, and 1,4-butanediol. This review shows not only emerging harm potentials but also some potential medical applications.

Loperamide, the "Poor Man's Methadone": Brief Review

Loperamide is widely available as an inexpensive, over-the-counter remedy commonly used for management of diarrhea. Although an opioid, at therapeutic doses it acts primarily on the gastrointestinal tissues; however, larger than recommended amounts facilitate central nervous system (CNS) penetration. Such high doses of loperamide have recently gained popularity among users of opioids to manage withdrawal symptomatology and, less frequently, to achieve psychoactive effects. Chronic loperamide use can result in development of tolerance and, upon abrupt cessation of use, withdrawal. With increasing prevalence of use, side-effects are noted, one particularly being life-threatening cardiac arrhythmias. Users are often not forthcoming and routine drug screens do not detect loperamide, so providers need to be alert to such practices in order to recognize intoxication, be able to screen for use, and facilitate entry into treatment.

Neurobiology of Kratom and its main alkaloid mitragynine

Kratom or its main alkaloid, mitragynine is derived from the plant Mitragyna speciosa Korth which is indigenous to Southeast Asian countries. This substance has become widely available in other countries like Europe and United States due to its opium- and coca-like effects. In this article, we have reviewed available reports on mitragynine and other M. speciosa extracts. M. speciosa has been proven to have a rewarding effect and is effective in alleviating the morphine and ethanol withdrawal effects. However, studies in human revealed that prolonged consumption of this plant led to dependence and tolerance while cessation caused a series of aversive withdrawal symptoms. Findings also showed that M. speciosa extracts possess antinociceptive, anti-inflammatory, anti-depressant, and muscle relaxant properties. Available evidence further supports the adverse effects of M. speciosa preparations, mitragynine on cognition. Pharmacological activities are mainly mediated via opioid receptors as well as neuronal Ca²⁺ channels, expression of cAMP and CREB protein and via descending monoaminergic system. Physicochemical properties of mitragynine have been documented which may further explain the variation in pharmacological responses. In summary, current researchs on its main indole alkaloid, mitragynine suggest both therapeutic and addictive potential but further research on its molecular effects is needed.

Abuse potential and adverse cognitive effects of mitragynine (kratom)

Mitragynine is the major psychoactive alkaloid of the plant kratom/ketum. Kratom is widely used in Southeast Asia as a recreational drug, and increasingly appears as a pure compound or a component of 'herbal high' preparations in the Western world. While mitragynine/kratom may have analgesic, muscle relaxant and anti-inflammatory effects, its addictive properties and effects on cognitive performance are unknown. We isolated mitragynine from the plant and performed a thorough investigation of its behavioural effects in rats and mice. Here we describe an addictive profile and cognitive impairments of acute and chronic mitragynine administration, which closely resembles that of morphine. Acute mitragynine has complex effects on locomotor activity. Repeated administration induces locomotor sensitization, anxiolysis and conditioned place preference, enhances expression of dopamine transporter- and dopamine receptor-regulating factor mRNA in the mesencephalon. While there was no increase in spontaneous locomotor activity during withdrawal, animals showed hypersensitivity towards small challenging doses for up to 14 days. Severe somatic withdrawal signs developed after 12 hours, and increased level of anxiety became evident after 24 hours of withdrawal. Acute mitragynine independently impaired passive avoidance learning, memory consolidation and retrieval, possibly mediated by a disruption of cortical oscillatory activity, including the suppression of low-frequency rhythms (delta and theta) in the electrocorticogram. Chronic mitragynine administration led to impaired passive avoidance and object recognition learning. Altogether, these findings provide evidence for an addiction potential with cognitive impairments for mitragynine, which suggest its classification as a harmful drug.

Social Functioning of Kratom (Mitragyna speciosa) Users in Malaysia

Kratom (Mitragyna speciosa) is an indigenous plant known for its traditional medicinal use, and for its addiction potential, in Southeast Asia. In recent years, kratom and its major alkaloid, mitragynine, spread worldwide with largely unknown effects on behavior and mental health. Recent studies show that kratom use can lead to dependence and that mitragynine works as an addictive drug in animal studies. Nevertheless, kratom preparations were also suggested as a less harmful substitute in opiate withdrawal. Potential side-effects of prolonged kratom use, however, are currently unclear. The aim of this study was to investigate the social functioning of regular kratom users in Malaysia. A cross-sectional survey was carried out in three northern states of Peninsular Malaysia investigating 293 regular kratom consumers using the Addiction Severity Index in a snowball sampling technique. Findings showed that regular kratom users do not experience major impairments in their social functioning, despite being dependent on kratom for prolonged periods. Our findings suggest that chronic kratom administration does not significantly impair social functioning of users in a natural context in Malaysia.

Discriminative stimulus properties of mitragynine (kratom) in rats

RATIONALE

Mitragynine (MG) is the primary active alkaloid extracted from the leaves of Mitragyna speciosa or kratom and exhibits pharmacological activities mediated by opioid receptors. The plant has been traditionally used for its opium and psychostimulant-like effects to increase work efficiency or as a substitute in the self-treatment of opiate addiction.

OBJECTIVES

The present study was performed to investigate the discriminative stimulus effects of MG in rats. The pharmacological mechanism of MG action and its derivative, 7-hydroxymitragynine (7-HMG) with a specific focus on opioid receptor involvement was examined in rats trained to discriminate morphine from vehicle. In order to study the dual actions of MG, the effect of cocaine substitution to the MG discriminative stimulus was also performed in MG-trained rats.

METHODS

Male Sprague Dawley rats were trained to discriminate MG from vehicle in a two-lever drug discrimination procedure under a tandem variable-interval (VI 60') fixed-ratio (FR 10) schedule of food reinforcement.

RESULTS

Rats acquired the MG discrimination (15.0 mg/kg, i.p.) which was similar to the acquisition of morphine discrimination (5.0 mg/kg, i.p.) in another group of rats. MG substituted fully to the morphine discriminative stimulus in a dose-dependent manner, suggesting pharmacological similarities between the two drugs. The administration of 7-HMG derivative in 3.0 mg/kg (i.p.) dose engendered full generalisation to the morphine discriminative stimulus. In addition, the MG stimulus also partially generalised to cocaine (10.0 mg/kg, i.p.) stimulus.

CONCLUSION

The present study demonstrates that the discriminative stimulus effect of MG possesses both opioid- and psychostimulant-like subjective effects.

Pharmacokinetics of mitragynine in man

BACKGROUND

Kratom, known botanically as Mitragyna speciosa (Korth.), is an indigenous tree in Southeast Asia. Kratom is currently easily available worldwide via special shops and the Internet to use as a drug of abuse, opioid alternative, or pain killer. So far, the pharmacokinetics of this plant has been studied only in animals, and there is no such study in humans. The major abundant active alkaloid in Kratom, mitragynine, is one of the promising new chemical substances to be developed as a new drug. The aim of this study was to examine the pharmacokinetics of mitragynine and assess the linearity in pharmacokinetics in chronic users.

METHODS

Since Kratom is illegal in Thailand, studies in healthy subjects would be unethical. We therefore conducted a prospective study by enrolling ten chronic, regular, healthy users. We adjusted the steady state in each subject by giving a known amount of Kratom tea for 7 days before commencement of the experiment. We admitted and gave different oral doses to subjects to confirm linearity in pharmacokinetics. The mitragynine blood concentrations at 17 times points and the urine concentrations during the 24-hour period were collected and measured by liquid chromatography-tandem mass spectrometry method.

RESULTS

Ten male subjects completed the study without adverse reactions. The median duration of abuse was 1.75 years. We analyzed one subject separately due to the abnormal behavior of blood concentration. From data of nine subjects, the pharmacokinetic parameters established were time to reach the maximum plasma concentration (0.83±0.35 hour), terminal half-life (23.24±16.07 hours), and the apparent volume of distribution (38.04±24.32 L/kg). The urine excretion of unchanged form was 0.14%. The pharmacokinetics were observed to be oral two-compartment model.

CONCLUSION

This was the first pharmacokinetic study in humans, which demonstrated linearity and was consistent with the oral two-compartment model with a terminal half-life of about 1 day. The pharmacokinetic linearity and parameters reported are necessary pharmacological information of Kratom, and there is a possibility for it to be developed medically as a pain killer or better opioid substitute in the future.

Kratom (Mitragyna speciosa) dependence, withdrawal symptoms and craving in regular users

BACKGROUND

Kratom (Mitragyna speciosa) preparations have been traditionally used in Southeast Asia for its medicinal properties. Lately, Kratom use has spread to Europe and the US, where abuse potential and health hazards increasingly emerge. This study is the first to measure systematically Kratom dependence, withdrawal symptoms, and drug craving in regular Kratom users in Malaysia.

METHODS

A cross-sectional survey of 293 regular Kratom users was conducted in the community across three northern peninsular states of Malaysia. The Leeds Dependence Questionnaire, Marijuana Withdrawal Checklist, and Marijuana Craving Questionnaire-Short Form were used to measure Kratom dependence, withdrawal and craving.

RESULTS

More than half of the regular users (>6 month of use) developed severe Kratom dependence problems, while 45% showed a moderate Kratom dependence. Physical withdrawal symptoms commonly experienced include muscle spasms and pain, sleeping difficulty, watery eyes/nose, hot flashes, fever, decreased appetite, and diarrhoea. Psychological withdrawal symptoms commonly reported were restlessness, tension, anger, sadness, and nervousness. The average amount of the psychoactive compound, mitragynine, in a single dose of a Kratom drink was 79mg, suggesting an average daily intake of 276.5mg. Regular users who consumed ≥3 glasses Kratom per day, had higher odds of developing severe Kratom dependence, withdrawal symptoms, and inability to control Kratom craving.

CONCLUSIONS

The findings from this study show that regular Kratom use is associated with drug dependency, development of withdrawal symptoms, and craving. These symptoms become more severe with prolonged use and suggest a stronger control of the drug.

Behavioral and neurochemical characterization of kratom (Mitragyna speciosa) extract

OBJECTIVE

Mitragyna speciosa and its extracts are named kratom (dried leaves, extract). It contains several alkaloids and is used in traditional medicine to alleviate musculoskeletal pain, hypertension, coughing, diarrhea, and as an opiate substitute for addicts. Abuse and addiction to kratom is described, and kratom has attracted increasing interest in Western countries. Individual effects of kratom on opioidergic, adrenergic, serotonergic, and dopaminergic receptors are known, but not all of the effects have been explained. Pharmacokinetic and pharmacodynamic data are needed.

METHODS

The effects of kratom extract on mice behavior were investigated following oral (po), intraperitoneal (ip), and intracerebroventricular (icv) application. Receptor-binding studies were performed.

RESULTS

In μ opioid receptor knockout mice (-/-) and wild type (+/+) animals, the extract reduced locomotor activity after ip and low po doses in +/+ animals, but not after icv administration. The ip effect was counteracted by 0.3 mg/kg of apomorphine sc, suggesting dopaminergic presynaptic activity. An analgesic effect was only found in -/- mice after icv application. Norbinaltorphimine abolished the analgesic effect, but not the inhibitory effect, on locomotor activity, indicating that the analgesic effect is mediated via κ opioid receptors. Oral doses, which did not diminish locomotor activity, impaired the acquisition of shuttle box avoidance learning. There was no effect on consolidation. Binding studies showed affinity of kratom to μ, δ, and κ opioid receptors and to dopamine D1 receptors.

CONCLUSIONS

The results obtained in drug-naïve mice demonstrate weak behavioral effects mediated via μ and κ opioid receptors.

From Kratom to mitragynine and its derivatives: physiological and behavioural effects related to use, abuse, and addiction

Kratom (or Ketum) is a psychoactive plant preparation used in Southeast Asia. It is derived from the plant Mitragyna speciosa Korth. Kratom as well as its main alkaloid, mitragynine, currently spreads around the world. Thus, addiction potential and adverse health consequences are becoming an important issue for health authorities. Here we reviewed the available evidence and identified future research needs. It was found that mitragynine and M. speciosa preparations are systematically consumed with rather well defined instrumentalization goals, e.g. to enhance tolerance for hard work or as a substitute in the self-treatment of opiate addiction. There is also evidence from experimental animal models supporting analgesic, muscle relaxant, anti-inflammatory as well as strong anorectic effects. In humans, regular consumption may escalate, lead to tolerance and may yield aversive withdrawal effects. Mitragynine and its derivatives actions in the central nervous system involve μ-opioid receptors, neuronal Ca²⁺ channels and descending monoaminergic projections. Altogether, available data currently suggest both, a therapeutic as well as an abuse potential.