Self-reported prevalence and severity of opioid and kratom (Mitragyna speciosa korth.) side effects

Kratom (Mitragyna speciosa) Use and Mental Health: A Systematic Review and Multilevel Meta-Analysis

INTRODUCTION

Kratom (Mitragyna speciosa) is a medicinal tree native to Southeast Asia. The present multilevel meta-analysis describes the association between kratom use and the positive and negative indicators of mental health.

METHODS

A total of thirty-six articles were included in the meta-analysis to examine the associations, using a random-effects model.

RESULTS

The pooled effect size showed a very small positive association between kratom use and negative indicators of mental health {r = 0.092, 95% confidence interval (CI) = [0.020, 0.164], p < 0.05}, while no significant association was found with positive indicators of mental health (r = -0.031, 95% CI = [-0.149, 0.087], p > 0.05). Pooled effect sizes of specific mental health outcomes indicated that kratom use showed only a small positive correlation with externalizing disorders (r = 0.201, 95% CI = [0.107, 0.300], p < 0.001). No significant association was found between kratom use and quality of life (r = 0.069, 95% CI = [-0.104, 0.242], p > 0.05) and internalizing disorders (r = -0.001, 95% CI = [-0.115, 0.095], p > 0.05). Multilevel moderator analysis showed that the pooled effect size of the association between kratom use and substance use disorder was stronger in Malaysia (r = 0.347, 95% CI = [0.209, 0.516], p < 0.001), and with the mean age (β1 = -0.035, 95% CI = [-0.055, -0.014], p = 0.003), and the drug profile of those who were not co-using other drugs (r = 0.347, 95% CI = [0.209, 0.516], p < 0.001).

CONCLUSION

The meta-analysis supports the kratom instrumentalization concept, in that a positive gain from kratom consumption can be achieved without any significant adverse associations with mental health.

Kratom Retail Availability in Fort Worth, Texas

Kratom use is associated with cannabis use, so retail availability may also be related. Kratom and Delta-8 THC (a psychoactive cannabis product) are federally unregulated, marketed as "natural," and often used for pain relief and/or relaxation. Kratom may have greater retail availability in more socioeconomically deprived areas because harmful substances are frequently marketed to lower-income communities. This study examined kratom retail availability in Fort Worth, Texas. Locations with alcohol, tobacco, and/or CBD licenses were called in July 2022: 1,025/1,223 (84%) answered the phone. T-tests examined potential differences in socioeconomic deprivation scores surrounding outlets by whether they sold kratom. Cross-tabulations examined overlap in kratom and Delta-8 THC availability. Kratom was available in 6% of locations. Most kratom retailers had a tobacco license (92%). However, most stores with a tobacco license did not sell kratom (14%), whereas most stores with a CBD license did (55%). Kratom availability was not associated with area deprivation scores. Most kratom retailers (95%) sold Delta-8 THC and two-thirds (65%) of Delta-8 THC retailers sold kratom. This study was the first to examine retail availability of kratom. Findings indicate the presence of niche stores specializing in the retail of federally unregulated substances.

An update on the clinical pharmacology of kratom: uses, abuse potential, and future considerations

INTRODUCTION

Kratom (Mitragyna speciosa) has generated substantial clinical and scientific interest as a complex natural product. Its predominant alkaloid mitragynine and several stereoisomers have been studied for activity in opioid, adrenergic, and serotonin receptors. While awaiting clinical trial results, the pre-clinical evidence suggests a range of potential therapeutic applications for kratom with careful consideration of potential adverse effects.

AREAS COVERED

The focus of this review is on the pharmacology, pharmacokinetics, and potential drug-drug interactions of kratom and its individual alkaloids. A discussion on the clinical pharmacology and toxicology of kratom is followed by a summary of user surveys and the evolving concepts of tolerance, dependence, and withdrawal associated with kratom use disorder.

EXPERT OPINION

With the increasing use of kratom in clinical practice, clinicians should be aware of the potential benefits and adverse effects associated with kratom. While many patients may benefit from kratom use with few or no reported adverse effects, escalating dose and increased use frequency raise the risk for toxic events in the setting of polysubstance use or development of a use disorder.

Knowledge of Kratom among Alabama Pharmacists

Kratom (Mitragyna speciosa) is a botanical substance whose leaves produce stimulant- and opioid-like effects. Kratom use has increased precipitously in the United States (U.S.) over the last decade, yet, in our experience, many pharmacists are unfamiliar with this herb. The purpose of this study was to assess pharmacists' awareness and knowledge of kratom. This cross-sectional study used an online questionnaire to preferentially solicit community pharmacists' knowledge of kratom and collect demographic information. The survey was sent via email to approximately 10,000 pharmacists, targeting those in the state of Alabama, U.S. Data were analyzed using descriptive statistics, and the Chi Square test was used to compare nominal data. A total of 257 participants responded to the survey. Almost 50% of participants had heard of kratom, and 50% had not. Compared to females, males were more likely to have heard of kratom (64% vs. 42%; p = 0.0015), as were pharmacists who worked for an independent pharmacy vs. a chain (61% vs. 41%; p = 0.025). Of the participants who had heard of kratom, only 14% considered themselves knowledgeable or very knowledgeable about the herb, and only 44% knew it was illegal in Alabama. These data indicate a need to further kratom education among community pharmacists in Alabama.

Kratom (Mitragyna speciosa) use in a sample of drug-dependent adolescents in rehabilitation for drug use in Malaysia

BACKGROUND

Leaves derived from the Kratom (Mitragyna speciosa) tree have been traditionally ingested for their curative properties by diverse groups of the population including people who use drugs (PWUDs) in Southeast Asia. This study investigated the motives for using kratom among drug-dependent adolescents.

METHODS

Eighty adolescents who were undergoing mandatory drug rehabilitation volunteered to participate in this mixed-method, cross-sectional study. All respondents answered a semi-structured questionnaire while a few were interviewed in-depth.

RESULTS

The majority were males (70%, n = 56/80). The respondents' mean age at admission was 18.2 years (SD = 1.40), and 65% were between 14 and 18 years old. Sixty-three percent (n = 50/80) had used crystal methamphetamine alone, while the rest had co-used crystal methamphetamine with heroin. About three-fifths (60%, n = 48/80) had a history of kratom use. Kratom was commonly used for many perceived benefits such as increasing energy, reducing crystal methamphetamine intake, intensifying euphoria, easing heroin withdrawal, as a heroin substitute and reducing heroin use. In addition, the multivariate analysis indicated that higher odds of kratom use were associated with those who were employed, used only crystal methamphetamine, were recent drug users, and had no prior incarceration history.

CONCLUSION

While kratom was being used for its multifold perceived benefits, it also functions as a means to self-treat withdrawal from illicit drug use among drug-dependent adolescents.

Evaluation of toxicity profile of kratom (Mitragyna speciosa Korth) decoction in rats

Mitragyna speciosa Korth also known as kratom, is an herbal drug preparation for its therapeutic properties and opioid-replacement therapy. Kratom is consumed in a brewed decoction form in Malaysia and to date, no studies have characterized its chemical and toxicity profile. Thus, this study aims to evaluate kratom decoction's safety and toxicity profile after 28 days of treatment. Mitragynine content was quantified in kratom decoction and used as a marker to determine the concentration. Male and female Sprague Dawley rats were orally treated with vehicle or kratom decoction (10, 50 or 150 mg/kg) and two satellite groups were treated with vehicle and kratom decoction (150 mg/kg). Blood and organs were collected for hematology, biochemical and histopathology analysis at the end of treatment. No mortality was found after 28 days of treatment and no significant changes in body weight and hematology profile, except for low platelet count. High amounts of uric acid, AST, ALT and alkaline phosphatase were found in the biochemical analysis. Histological investigation of the heart and lungs detected no alterations except for the kidney, liver and brain tissues. In conclusion, repeated administration of kratom decoction provided some evidence of toxicity in the kidney and liver with no occurrence of mortality.

The Health Impact of Long-Term Kratom (Mitragyna Speciosa) Use in Southern Thailand

BACKGROUND

Mitragyna speciosa or Kratom has been used in Thailand traditionally for its medicinal value. Despite case reports of kratom consumption causing adverse effects, research on its long-term health impact is limited. This study examines the long-term health impact of kratom use among people in Southern Thailand.

METHODS

Three community-based surveys were conducted from 2011 to 2015. In the first and second surveys (2011 and 2012) a total of 1,118 male respondents comprising 355 regular kratom users, 171 occasional kratom users, 66 ex-users, and 592 non-users aged 25 or above, were recruited from 40 villages. All respondents were followed up in this study. However, not all respondents were successfully followed up throughout the entire set of studies.

RESULTS

Common health complaints were no more common among kratom users than ex- and non-users, but more regular than occasional users claimed kratom to be addictive. Those with high kratom dependence scores were more likely to experience intense withdrawal symptoms, which developed 1-12 h after the last kratom intake. Over half (57.9%) of regular users had experienced intoxication effects compared to only 29.3% of occasional users. Kratom users were less likely to have a history of chronic diseases such as diabetes, hypertension, dyslipidemia than ex- and non-users.

CONCLUSION

Regular long-term chewing of fresh kratom leaves was not related to an increase in common health complaints, but may pose a drug dependence risk. Severe kratom dependents were more likely to suffer from intense withdrawal symptoms. Medical records revealed no death due to traditional kratom use, but the high prevalence of tobacco or/and hand rolled cigarette smoking among kratom users should be of concern.

Clinical Implications of Kratom (Mitragyna speciosa) Use: a Literature Review

Purpose of Review

This work aims to provide an up-to-date review of the preclinical and clinical scientific literature on the therapeutic value of kratom to better understand the underlying mechanisms related to its use and inform future therapeutic applications.

Recent Findings

A growing number of studies, mainly of cross-sectional nature, describe the widespread use of kratom by individuals to self-treat pain, psychiatric symptoms, and substance use disorders (SUD) outside a controlled clinical setting. Preclinical evidence suggests kratom is effective as an analgesic agent and might decrease the self-administration of other drugs. A randomized controlled trial has further supported kratom's therapeutic value as an analgesic. Investigations in nonclinical samples of long-term kratom users also indicate its therapeutic benefit in managing SUD symptoms (e.g., craving) and long-term or acute symptoms (e.g., withdrawal) for alcohol, opioids, and other illicit drugs. However, episodes of kratom-related intoxications have also been reported, often due to the adulteration and the contamination of kratom products mainly sold online or mixed toxicities when consumed outside clinical and traditional settings.

Summary

Evidence on the clinical implications of kratom use is still limited and uncertain, with kratom research constantly evolving. Therefore, further randomized trials are needed.

Adolescent kratom exposure affects cognitive behaviours and brain metabolite profiles in Sprague-Dawley rats

Adolescence is a critical developmental period during which exposure to psychoactive substances like kratom (Mitragyna speciosa) can cause long-lasting deleterious effects. Here, we evaluated the effects of mitragynine, the main alkaloid of kratom, and lyophilised kratom decoction (LKD) on cognitive behaviours and brain metabolite profiles in adolescent rats. Male Sprague-Dawley rats (Postnatal day, PND31) were given vehicle, morphine (5 mg/kg), mitragynine (3, 10, or 30 mg/kg), or LKD (equivalent dose of 30 mg/kg mitragynine) for 15 consecutive days. Later, a battery of behavioural testing was conducted, brain was extracted and metabolomic analysis was performed using LCMS-QTOF. The results showed that mitragynine did not affect the recognition memory in the novel object recognition task. In the social interaction task, morphine, mitragynine, and LKD caused a marked deficit in social behaviour, while in Morris water maze task, mitragynine and LKD only affected reference memory. Metabolomic analysis revealed distinct metabolite profiles of animals with different treatments. Several pathways that may be involved in the effects of kratom exposure include arachidonic acid, pantothenate and CoA, and tryptophan pathways, with several potential biomarkers identified. These findings suggest that adolescent kratom exposure can cause cognitive behavioural deficits that may be associated with changes in the brain metabolite profiles.

Qualitative content analysis of public responses to an FDA inquiry on the impact of scheduling changes to kratom

BACKGROUND

The legal status of kratom in the United States is complex and varies by state. The U.S. Food and Drug Administration (FDA) and the U.S. Drug Enforcement Administration have repeatedly subjected kratom to regulatory review. However, there hasn't been a systematic review of the public's perception of kratom. The present study analyzed open-ended responses from the public to an FDA solicitation for information regarding kratom with the goal of providing a comprehensive assessment of motives for kratom use.

METHODS

To guide decisions regarding kratom regulation, the FDA solicited comments regarding kratom abuse potential, medical usefulness, and impact of scheduling changes from July through August 2021 and posted them to the Federal Register website. We analyzed comments posted during the first 6 weeks of comment solicitation (6,353) using an inductive approach via qualitative content analysis.

RESULTS

Respondents reported 106 independent health-related reasons for kratom use, with most categorized as mental health, pain management, substance use disorder, or miscellaneous purposes that included increasing focus, treating insomnia, and decreasing fatigue. Neurological diseases and digestive disorders were also reported. Relatively few (< 2%) responses reported recreational use, abuse potential, or adverse effects of kratom.

CONCLUSIONS

Although kratom is not approved as a safe and effective therapy for any indication, individuals use kratom for a broad spectrum of health-related purposes. Limitations of this study include potential bias for respondents with perceived positive experiences using kratom, lack of demographics data, and lack of independent verification of claims made by respondents. Regardless, this study reflects perceptions regarding the therapeutic uses of kratom and provides insight into potential individual-level consequences of regulating kratom in the U.S. It is important to study the public's perception of kratom use, which can aid regulatory purposes and provide clinically important information on individuals' use and valuation of kratom.

A Case of Severe Kratom Addiction Contributing to a Suicide Attempt

Kratom is a plant product native to Southeast Asia that is surging in popularity in the United States as consumers look for natural remedies for ailments like chronic pain, anxiety, and even opioid addiction. Kratom's risks are largely unknown, and the market is poorly regulated. Americans typically get advice from online forums and purchase powder formulations from tobacco shops or obscure websites. These risks are highlighted in this case of a 38-year-old woman with a history of major depressive disorder and opioid use disorder who switched from Suboxone to kratom and became addicted, eventually consuming large quantities per day. Amplified by other stressors, she reached a breaking point and overdosed on her regular medications for depression. At the psychiatric hospital, she exhibited classic kratom withdrawal symptoms, including vague abdominal pain and restlessness. After eight days of treatment, her symptoms eventually abated, and she was discharged on Suboxone.

Kratom as an opioid alternative: harm, or harm reduction? A systematic review of literature

Background: Kratom (Mitragyna speciosa Korth.) products are increasingly endorsed for self-management of multiple ailments, including as opioid substitution. The FDA has expressed that there is no evidence to indicate that this botanical is safe or effective for any medical use.Objective: We systematically review the current state of the literature concerning the impact of kratom and its alkaloids in all paradigms that involve opioids.Methods: A keyword search of online literature databases identified 16 preclinical studies, 25 case reports, and 10 observational studies meeting our pre-selected criteria.Results: All rodent models support alkaloids' action on opioid receptors, translating in their ability to mitigate opioid withdrawal. Some studies found mitragynine (MG) to have less reinforcing properties than morphine, and possessing tolerance-sparing properties when coadministered with morphine. Two studies that assessed 7-hydroxymitragynine (7OHMG) found it to substitute for morphine with potential for tolerance and dependence. Aside from addiction development, case reports outline a variety of confounding toxicities. Ten surveys of users, some conducted with assistance from pro-kratom lobbying organizations, find a high self-reported efficacy as an opioid substitute, with minimal reported adverse effects.Conclusion: With no reported controlled human clinical trials, in the light of rising concerns surrounding kratom's liabilities, there is insufficient evidence to allow any conclusions to be drawn. Case reports and observational studies carry significant bias toward harm and efficacy, respectively. Existing animal studies are heterogeneous in methodology and ultimately findings, with concern for interspecies variability and human translatability. Further research should investigate the safety and efficacy of using kratom alkaloids as opioid substitutes.

Kratom: Substance of Abuse or Therapeutic Plant?

Kratom is the common term for Mitragyna speciosa and its products. Its major active compounds are mitragynine and 7-hydroxymitragynine. An estimated 2.1 million US residents used kratom in 2020, as a "legal high" and self-medication for pain, opioid withdrawal, and other conditions. Up to 20% of US kratom users report symptoms consistent with kratom use disorder. Kratom use is associated with medical toxicity and death. Causality is difficult to prove as almost all cases involve other psychoactive substances. Daily, high-dose use may result in kratom use disorder and opioid-like withdrawal on cessation of use. These are best treated with buprenorphine.

The Prevalence and Psychosocial Correlates of Ketum (Mitragyna speciosa) Use among Individuals on Methadone Maintenance Therapy Programme in Hospital Taiping, Malaysia

Ketum use is significantly prevalent amongst individuals in the northern states of Peninsular Malaysia. This study aims to investigate the prevalence and psychosocial correlates of Ketum use in individuals who are in the Methadone Maintenance Therapy (MMT) Programme at the Hospital Taiping. This is a cross-sectional study conducted in the methadone clinic at the Hospital Taiping. The study instruments used were Subjective Opiate Withdrawal Scale (SOWS), Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) questionnaire, and Kratom Dependence Scale (KDS). A total of 215 subjects were recruited for this study. The prevalence of ketum users was 49.3% (n = 106). Chinese and Indian ethnicity had a lower tendency to use ketum compared to Malay ethnicity, with OR = 0.386 (95% CI 0.134, 1.113) and 0.119 (95% CI 0.035, 0.408), respectively. Individuals who used other illicit drugs had a higher tendency to use ketum with the adjusted OR = 9.914 (95% CI: 1.109, 88.602). Every one unit increase in SOWS increased the odds of being a ketum user by 1.340 (95% CI: 1.070, 1.677), whereas every one unit increase in duration in the MMT programme reduced the odds of being a ketum user by 0.990 (95% CI: 0.982, 0.998). Ketum use is prevalent amongst those in the MMT programme in this study. The high prevalence of ketum use is of concern and further interventions should be carried out to address this.

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.

Searching for a Signal: Self-Reported Kratom Dose-Effect Relationships Among a Sample of US Adults With Regular Kratom Use Histories

There is limited understanding regarding kratom use among US adults. Although motivations for use are increasingly understood, typical kratom doses, threshold of (low and high) doses for perceived effectiveness, and effects produced during cessation are not well documented. We aimed to extend prior survey work by recruiting adults with current and past kratom exposure. Our goal was to better understand kratom dosing, changes in routines, and perception of effects, including time to onset, duration, and variability of beneficial and adverse outcomes from use and cessation. Among respondents who reported experiencing acute kratom effects, we also sought to determine if effects were perceived as helpful or unhelpful in meeting daily obligations. Finally, we attempted to detect any signal of a relationship between the amount of kratom consumed weekly and weeks of regular use with ratings of beneficial effects from use and ratings of adverse effects from cessation. We conducted an online survey between April-May 2021 by re-recruiting participants from a separate study who reported lifetime kratom use. A total of 129 evaluable surveys were collected. Most (59.7%) had used kratom >100 times and reported currently or having previously used kratom >4 times per week (62 weeks on average). Under half (41.9%) reported that they considered themselves to be a current "regular kratom user." A majority (79.8%) reported experiencing acute effects from their typical kratom dose and that onset of effects began in minutes but dissipated within hours. Over a quarter reported that they had increased their kratom dose since use initiation, whereas 18.6% had decreased. Greater severity of unwanted effects from ≥1 day of kratom cessation was predicted by more weeks of regular kratom use (β = 6.74, p = 0.02). Acute kratom effects were largely reported as compatible with, and sometimes helpful in, meeting daily obligations. In the absence of human laboratory studies, survey methods must be refined to more precisely assess dose-effect relationships. These can help inform the development of controlled observational and experimental studies needed to advance the public health understanding of kratom product use.

Ameliorative effects of alkaloid extract from Mitragyna speciosa (Korth.) Havil. Leaves on methamphetamine conditioned place preference in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Mitragyna speciosa (Korth.) Havil., popularly known as Kratom (KT), is a medicinal plant used for pain suppression in Southeast Asia. It has been claimed to assist drug users withdraw from methamphetamine (METH) dependence. However, its use was controversial and not approved yet.

AIM OF THE STUDY

This study was conducted to characterize local field potential (LFP) patterns in the nucleus accumbens (NAc) and the hippocampus (HP) in mice with METH conditioned place preference (CPP) that were treated with KT alkaloid extract.

MATERIALS AND METHODS

Male Swiss albino ICR mice were implanted with intracraneal electrodes into the NAc and HP. To induce METH CPP, animals were injected intraperitoneally once a day with METH (1 mg/kg) and saline (0.9% w/v) alternately and put into METH/saline compartments to experience the associations between drug/saline injection and the unique environmental contexts for 10 sessions. Control group received saline injection paired with both saline/saline compartments. On post-conditioning day, effects of 40 (KT40), 80 (KT80) mg/kg KT alkaloid extract and 20 mg/kg bupropion (BP) on CPP scores and LFP powers and NAc-HP coherence were tested.

RESULTS

Two-way ANOVA revealed significant induction of CPP by METH sessions (P < 0.01). Multiple comparisons indicated that METH CPP was completely abolished by KT80 (P < 0.001). NAc gamma I (30.0-44.9 Hz) and HP delta (1.0-3.9 Hz) powers were significantly increased in mice with METH CPP (P < 0.01). The elevated NAc gamma I was significantly suppressed by KT80 (P < 0.05) and the increased HP delta was significantly reversed by KT40 (P < 0.01) and KT80 (P < 0.001). In addition, NAc-HP coherence was also significantly increased in gamma I (30.0-44.9 Hz) frequency range (P < 0.05) but it was reversed by KT80 (P < 0.05). Treatment with BP did not produce significant effect on these parameters.

CONCLUSIONS

These findings demonstrated that KT alkaloid extract significantly reversed CPP scores and LFP patterns induced by METH administration. The ameliorative effects of the extract might be beneficial for treatment of METH craving and addiction.

Mitragyna Species as Pharmacological Agents: From Abuse to Promising Pharmaceutical Products

Mitragyna is a genus belonging to the Rubiaceae family and is a plant endemic to Asia and Africa. Traditionally, the plants of this genus were used by local people to treat some diseases from generation to generation. Mitragyna speciosa (Korth.) Havil. is a controversial plant from this genus, known under the trading name “kratom”, and contains more than 40 different types of alkaloids. Mitragynine and 7-hydroxymitragynine have agonist morphine-like effects on opioid receptors. Globally, Mitragyna plants have high economic value. However, regulations regarding the circulation and use of these commodities vary in several countries around the world. This review article aims to comprehensively examine Mitragyna plants (mainly M. speciosa) as potential pharmacological agents by looking at various aspects of the plants. A literature search was performed and information collected using electronic databases including Scopus, ScienceDirect, PubMed, directory open access journal (DOAJ), and Google Scholar in early 2020 to mid-2021. This narrative review highlights some aspects of this genus, including historical background and botanical origins, habitat, cultivation, its use in traditional medicine, phytochemistry, pharmacology and toxicity, abuse and addiction, legal issues, and the potential of Mitragyna species as pharmaceutical products.

A systematic review of (pre)clinical studies on the therapeutic potential and safety profile of kratom in humans

INTRODUCTION

Kratom (Mitragyna speciosa) is a tropical plant traditionally used as an ethnomedicinal remedy for several conditions in South East Asia. Despite the increased interest in its therapeutical benefits in Western countries, little scientific evidence is available to support such claims, and existing data remain limited to kratom's chronic consumption.

OBJECTIVE

Our study aims to investigate (pre)clinical evidence on the efficacy of kratom as a therapeutic aid and its safety profile in humans.

METHODS

A systematic literature search using PubMed and the Medline database was conducted between April and November 2020.

RESULTS

Both preclinical (N = 57) and clinical (N = 18) studies emerged from our search. Preclinical data indicated a therapeutic value in terms of acute/chronic pain (N = 23), morphine/ethanol withdrawal, and dependence (N = 14), among other medical conditions (N = 26). Clinical data included interventional studies (N = 2) reporting reduced pain sensitivity, and observational studies (N = 9) describing the association between kratom's chronic (daily/frequent) use and safety issues, in terms of health consequences (e.g., learning impairment, high cholesterol level, dependence/withdrawal).

CONCLUSIONS

Although the initial (pre)clinical evidence on kratom's therapeutic potential and its safety profile in humans is encouraging, further validation in large, controlled clinical trials is required.

Evaluation of Kratom Opioid Derivatives as Potential Treatment Option for Alcohol Use Disorder

Background and Purpose:Mitragyna speciosa extract and kratom alkaloids decrease alcohol consumption in mice at least in part through actions at the δ-opioid receptor (δOR). However, the most potent opioidergic kratom alkaloid, 7-hydroxymitragynine, exhibits rewarding properties and hyperlocomotion presumably due to preferred affinity for the mu opioid receptor (µOR). We hypothesized that opioidergic kratom alkaloids like paynantheine and speciogynine with reduced µOR potency could provide a starting point for developing opioids with an improved therapeutic window to treat alcohol use disorder.

Experimental Approach: We characterized paynantheine, speciociliatine, and four novel kratom-derived analogs for their ability to bind and activate δOR, µOR, and κOR. Select opioids were assessed in behavioral assays in male C57BL/6N WT and δOR knockout mice.

Key Results: Paynantheine (10 mg∙kg⁻¹, i.p.) produced aversion in a limited conditioned place preference (CPP) paradigm but did not produce CPP with additional conditioning sessions. Paynantheine did not produce robust antinociception but did block morphine-induced antinociception and hyperlocomotion. Yet, at 10 and 30 mg∙kg⁻¹ doses (i.p.), paynantheine did not counteract morphine CPP. 7-hydroxypaynantheine and 7-hydroxyspeciogynine displayed potency at δOR but limited µOR potency relative to 7-hydroxymitragynine in vitro, and dose-dependently decreased voluntary alcohol consumption in WT but not δOR in KO mice. 7-hydroxyspeciogynine has a maximally tolerated dose of at least 10 mg∙kg⁻¹ (s.c.) at which it did not produce significant CPP neither alter general locomotion nor induce noticeable seizures.

Conclusion and Implications: Derivatizing kratom alkaloids with the goal of enhancing δOR potency and reducing off-target effects could provide a pathway to develop novel lead compounds to treat alcohol use disorder with an improved therapeutic window.

Clinical Pharmacology of the Dietary Supplement, Kratom (Mitragyna speciosa)

Kratom (Mitragyna speciosa) consists of over 40 alkaloids with two of them, mitragynine (MG) and 7-OH-mitragynine (7-OH-MG) being the main psychoactive compounds. MG and 7-OH-MG each target opioid receptors and have been referred to as atypical opioids. They exert their pharmacologic effects on the μ, δ, and κ opioid receptors. In addition, they affect adrenergic, serotonergic, and dopaminergic pathways. Kratom has been touted as an inexpensive, legal alternative to standard opioid replacement therapy such as methadone and buprenorphine. Other uses for kratom include chronic pain, attaining a "legal high," and numerous CNS disorders including anxiety depression and post-traumatic stress disorder (PTSD). Kratom induces analgesia and mild euphoria with a lower risk of respiratory depression or adverse central nervous system effects compared to traditional opioid medications. Nonetheless, kratom has been associated with both physical and psychological dependence with some individuals experiencing classic opioid withdrawal symptoms upon abrupt cessation. Kratom use has been linked to serious adverse effects including liver toxicity, seizures, and death. These risks are often compounded by poly-substance abuse. Further, kratom may potentiate the toxicity of coadministered medications through modulation of cytochrome P450, P-glycoprotein, and uridine diphosphate glucuronosyltransferase enzymes (UGDT). In 2016 the U.S. Drug Enforcement Administration (DEA) took steps to classify kratom as a federal schedule 1 medication; however, due to public resistance, this plan was set aside. Until studies are conducted that define kratom's role in treating opioid withdrawal and/or other CNS conditions, kratom will likely remain available as a dietary supplement for the foreseeable future. This article is protected by copyright. All rights reserved.

Combinations of indole based alkaloids from Mitragyna speciosa (Kratom) and cisplatin inhibit cell proliferation and migration of nasopharyngeal carcinoma cell lines

ETHNOPHARMACOLOGICAL RELEVANCE

Mitragyna speciosa (Korth.) or kratom is a medicinal plant indigenous to Southeast Asia. The leaf of M. speciosa is used as a remedy in pain management including cancer related pain, in a similar way as opioids and cannabis. Despite its well-known analgesic effect, there is a scarce of information on the cancer-suppressing potential of M. speciosa and its active constituents.

AIM OF THE STUDY

To assess the potential applicability of M. speciosa alkaloids (mitragynine, speciociliatine or paynantheine) as chemosensitizers for cisplatin in Nasopharyngeal carcinoma (NPC) cell lines.

MATERIALS AND METHODS

The cytotoxic effects of the extracts, fractions and compounds were determined by conducting in vitro cytotoxicity assays. Based on the cytotoxic screening, the alkaloid extract of M. speciosa exhibited potent inhibitory effect on the NPC cell line NPC/HK1, and therefore, was chosen for further fractionation and purification. NPC cell lines NPC/HK1 and C666-1 were treated with combinations of cisplatin and M. speciosa alkaloids combinations in 2D monolayer culture. The effect of cisplatin and mitragynine as a combination on cell migration was tested using in vitro wound healing and spheroid invasion assays.

RESULTS

In our bioassay guided isolation, both methanolic and alkaloid extracts showed mild to moderate cytotoxic effect against the NPC/HK1 cell line. Both NPC cell lines (NPC/HK1 and C666-1) were insensitive to single agent and combination treatments of the M. speciosa alkaloids. However, mitragynine and speciociliatine sensitized the NPC/HK1 and C666-1 cells to cisplatin at ~4- and >5-fold, respectively in 2D monolayer culture. The combination of mitragynine and cisplatin also significantly inhibited cell migration of the NPC cell lines. Similarly, the combination also of mitragynine and cisplatin inhibited growth and invasion of NPC/HK1 spheroids in a dose-dependent manner. In addition, the spheroids did not rapidly develop resistance to the drug combinations at higher concentrations over 10 days.

CONCLUSION

Our data indicate that both mitragynine and speciociliatine could be potential chemosensitizers for cisplatin. Further elucidation focusing on the drug mechanistic studies and in vivo studies are necessary to support delineate the therapeutic applicability of M. speciosa alkaloids for NPC treatment.

Comparative Toxicity Assessment of Kratom Decoction, Mitragynine and Speciociliatine Versus Morphine on Zebrafish (Danio rerio) Embryos

Background: Kratom (Mitragyna speciosa Korth), a popular opioid-like plant holds its therapeutic potential in pain management and opioid dependence. However, there are growing concerns about the safety or potential toxicity risk of kratom after prolonged use.

Aim of the study: The study aimed to assess the possible toxic effects of kratom decoction and its major alkaloids, mitragynine, and speciociliatine in comparison to morphine in an embryonic zebrafish model.

Methods: The zebrafish embryos were exposed to kratom decoction (1,000–62.5 μg/ml), mitragynine, speciociliatine, and morphine (100–3.125 μg/ml) for 96 h post-fertilization (hpf). The toxicity parameters, namely mortality, hatching rate, heart rate, and morphological malformations were examined at 24, 48, 72, and 96 hpf, respectively.

Results: Kratom decoction at a concentration range of ≥500 μg/ml caused 100% mortality of zebrafish embryos and decreased the hatching rate in a concentration-dependent manner. Meanwhile, mitragynine and speciociliatine exposure resulted in 100% mortality of zebrafish embryos at 100 μg/ml. Both alkaloids caused significant alterations in the morphological development of zebrafish embryos including hatching inhibition and spinal curvature (scoliosis) at the highest concentration. While exposure to morphine induced significant morphological malformations such as pericardial oedema, spinal curvature (lordosis), and yolk edema in zebrafish embryos.

Conclusion: Our findings provide evidence for embryonic developmental toxicity of kratom decoction and its alkaloids both mitragynine and speciociliatine at the highest concentration, hence suggesting that kratom consumption may have potential teratogenicity risk during pregnancy and thereby warrants further investigations.

Therapeutic benefit with caveats?: Analyzing social media data to understand the complexities of kratom use

BACKGROUND

Mitragyna speciosa, referred to as "kratom", is increasingly used in the United States for self-treating pain, psychiatric, and substance use disorder symptoms. It is used by some to attenuate opioid withdrawal and as a longer-term drug substitute. Most self-report data have come from online surveys, small in-person surveys, and case reports. These may not be representative of the broader kratom-using population.

PURPOSE

Analyze user-generated social media posts to determine if independent, descriptive accounts are generally consistent with prior U.S. kratom survey findings and gain a more nuanced understanding of kratom use patterns.

METHODS

Reddit posts mentioning kratom from 42 subreddits between June 2019-July 2020 were coded by two independent raters.

FINDINGS

Relevant posts (number of comments, upvotes, and downvotes) from 1274 posts comprised the final sample (n = 280). Of the 1521 codes applied, 1273 (83.69%) were concordant. Desirable kratom effects were described among a majority, but so too were adverse effects. Reports of kratom as acute self-treatment for opioid withdrawal were more prominent compared to longer-term opioid substitution. Quantitative analysis found higher kratom doses associated (p < .001) with greater odds of reported kratom addiction (OR = 3.56) or withdrawal (OR = 5.88), with slightly lower odds of desirable effects (OR = 0.53, p = .014). Despite perceived therapeutic benefits, kratom was characterized by some in terms of addiction that, in some cases, appeared dose-dependent. Polydrug use was also prominently discussed.

CONCLUSIONS

Results validated many prior survey findings while illustrating complexities of kratom use that are not being fully captured and require continued investigation.

Site selective C-H functionalization of Mitragyna alkaloids reveals a molecular switch for tuning opioid receptor signaling efficacy

Mitragynine (MG) is the most abundant alkaloid component of the psychoactive plant material "kratom", which according to numerous anecdotal reports shows efficacy in self-medication for pain syndromes, depression, anxiety, and substance use disorders. We have developed a synthetic method for selective functionalization of the unexplored C11 position of the MG scaffold (C6 position in indole numbering) via the use of an indole-ethylene glycol adduct and subsequent iridium-catalyzed borylation. Through this work we discover that C11 represents a key locant for fine-tuning opioid receptor signaling efficacy. 7-Hydroxymitragynine (7OH), the parent compound with low efficacy on par with buprenorphine, is transformed to an even lower efficacy agonist by introducing a fluorine substituent in this position (11-F-7OH), as demonstrated in vitro at both mouse and human mu opioid receptors (mMOR/hMOR) and in vivo in mouse analgesia tests. Low efficacy opioid agonists are of high interest as candidates for generating safer opioid medications with mitigated adverse effects.

Kratom exposures among older adults reported to U.S. poison centers, 2014-2019

BACKGROUND

In recent years, use of the herbal supplement kratom has increased in the United States. The reasons for use include pain relief, particularly as a substitute for opioids.

OBJECTIVES

To describe epidemiologic trends in kratom-related exposures among older adults reported to U.S. poison centers.

DESIGN

Retrospective analysis of American Association of Poison Control Center's National Poison Data System (NPDS).

SETTING

Data from all U.S. poison centers from 2014 to 2019 were examined.

PARTICIPANTS

Kratom exposure cases involving adults aged 18 and older. Kratom cases were identified by product and NPDS generic codes. Non-human and information-only calls were excluded. Data were examined for all calls for exposures among adults, with a focus on older adults aged 60-69 years and above 70 years.

MEASUREMENTS

Descriptive analyses were used to characterize individual demographic, exposure information, clinical effects, and medical outcomes associated with kratom exposures among older adults. Comparisons across age groups (18-59, 60-69, and 70+ years) were made using Fisher's exact tests.

RESULTS

Among 3484 kratom-related exposures reported between 2014 and 2019, 4.6% (n = 162) were among adults over 60 years. The number of kratom-related exposures increased over time. Most cases originated with calls from healthcare facilities (81.1%) and involved kratom as a single ingestant (63.0%). The reason for most ingestions was intentional (74.5%). One in five exposures among adults aged 70 and older involved an adverse reaction (e.g., drug interaction; 21.9%), compared with 12.3% among ages 60-69 and 9.6% among ages 18-59 years. Neurological and cardiovascular clinical effects were observed. Twenty-three deaths were observed among older adults.

CONCLUSION

Healthcare providers and older adult patients should be aware of the potential risks of kratom use, including medication interactions and falls. When reviewing medication lists, providers should query this population for all medications and substances being used, especially in people being treated for pain.

Kratom pharmacology: Clues from planarians exposed to mitragynine

Mitragynine (MG), the most prevalent bioactive alkaloid in kratom, displays nanomolar affinity for µ, κ and δ opioid receptors and produces opioid-dependent antinociception and dependence in rats. Here, using a battery of behavioral assays, we investigated MG effects in planarians. Acute MG exposure (< 100 μM) did not affect planarian motility or environmental preference, but reduced motility was detected during abstinence from chronic MG (1, 10 μM). MG (10 μM) produced place conditioning effects that were reduced by naltrexone (10  μΜ). These results suggest that MG produces opioid-sensitive reinforcing effects in planarians and MG pharmacology is conserved across different species.

Outcomes of mothers and newborns to prenatal exposure to kratom: a systematic review

Kratom is a legal, widely available substance that contains opioid agonist alkaloids. Due to the marketing of kratom as an opioid alternative for treatment of pain, anxiety, depression, or to reduce opioid withdrawal symptoms, the use of kratom has increased among persons in the USA including pregnant women. This systematic review of the peer-reviewed literature regarding kratom in relation to maternal and infant outcomes resulted in analysis of six case reports of prenatal kratom exposure. Maternal and infant withdrawal from kratom exposure was described in each case, resulting in pharmacologic treatment for both mothers and infants.

Kratom use for depression/anxiety self-management: challenges during the COVID-19 pandemic - A case report

Background

Kratom is a psychoactive plant preparation originating from Southeast Asia. It has been used as a recreational and performance drug in Southeast Asia, and is now increasingly used in Europe and the U.S.

Case report

We describe the case of a 63-year-old man who presented for treatment after his long-term Kratom use failed as a self-management for persistent major depression (ICD 10: F33.2) and a generalized anxiety disorder (ICD-10: F41.1). The failure coincided with emerging stress at the beginning of the COVID-19 pandemic. The patient suffered from childhood on from ruminative thinking and depressive mood, which was treated in several settings during his life. He started to use alcohol to control his depression, but developed an alcohol addiction. This was successfully treated and the patient remained abstinent for more than 25 years afterwards. About 7 years ago, he started to use Kratom 3–4 times daily on a regular, but constant rate. Kratom use worked efficiently as a self-management of his depression with no escalation of dosing. It was also very effective in reducing Morbus Menière symptoms of tinnitus and sudden hearing loss, which eventually allowed regular performance as a caregiver in a demanding job on shift-work. During recently increased stress load in the work environment and the COVID-19 pandemic, the established Kratom doses failed to control hyperarousal and mental nervousness. The patient was treatment seeking and subsequently detoxified from Kratom. Anxiety- and depression management was shifted to treatment attempts with Lorazepam, Venlafaxine, Opipramol, Mirtazapine and psychotherapy.

Conclusion

Kratom instrumentalization for self-management of depression and anxiety may effectively work without causing escalation of drug use and addiction, but may be limited by a temporary increase in psychological stress load and a relapse into major depression and generalized anxiety disorder.

Lyophilized Kratom Tea as a Therapeutic Option for Opioid Dependence

BACKGROUND

Made as a tea, the Thai traditional drug "kratom" reportedly possesses pharmacological actions that include both a coca-like stimulant effect and opium-like depressant effect. Kratom has been used as a substitute for opium in physically-dependent subjects. The objective of this study was to evaluate the antinociception, somatic and physical dependence produced by kratom tea, and then assess if the tea ameliorated withdrawal in opioid physically-dependent subjects.

METHODS

Lyophilized kratom tea (LKT) was evaluated in C57BL/6J and opioid receptor knockout mice after oral administration. Antinociceptive activity was measured in the 55 °C warm-water tail-withdrawal assay. Potential locomotor impairment, respiratory depression and locomotor hyperlocomotion, and place preference induced by oral LKT were assessed in the rotarod, Comprehensive Lab Animal Monitoring System, and conditioned place preference assays, respectively. Naloxone-precipitated withdrawal was used to determine potential physical dependence in mice repeatedly treated with saline or escalating doses of morphine or LKT, and LKT amelioration of morphine withdrawal. Data were analyzed using one- and two-way ANOVA.

RESULTS

Oral administration of LKT resulted in dose-dependent antinociception (≥1 g/kg, p.o.) absent in mice lacking the mu-opioid receptor (MOR) and reduced in mice lacking the kappa-opioid receptor. These doses of LKT did not alter coordinated locomotion or induce conditioned place preference, and only briefly reduced respiration. Repeated administration of LKT did not produce physical dependence, but significantly decreased naloxone-precipitated withdrawal in morphine dependent mice.

CONCLUSIONS

The present study confirms the MOR agonist activity and therapeutic effect of LKT for the treatment of pain and opioid physical dependence.

Pharmacology of Herbal Sexual Enhancers: A Review of Psychiatric and Neurological Adverse Effects

Sexual enhancers increase sexual potency, sexual pleasure, or libido. Substances increasing libido alter the concentrations of specific neurotransmitters or sex hormones in the central nervous system. Interestingly, the same pathways are involved in the mechanisms underlying many psychiatric and neurological disorders, and adverse reactions associated with the use of aphrodisiacs are strongly expected. However, sexual enhancers of plant origin have gained popularity over recent years, as natural substances are often regarded as a safer alternative to modern medications and are easily acquired without prescription. We reviewed the psychiatric and neurological adverse effects associated with the consumption of herbal aphrodisiacs Areca catechu L., Argemone Mexicana L., Citrus aurantium L., Eurycoma longifolia Jack., Lepidium meyenii Walp., Mitragyna speciosa Korth., Panax ginseng C. A. Mey, Panax quinquefolius L., Pausinystalia johimbe (K. Schum.) Pierre ex Beille, Piper methysticum G. Forst., Ptychopetalum olacoides Benth., Sceletium tortuosum (L.) N. E. Brown, Turnera diffusa Willd. ex. Schult., Voacanga africana Stapf ex Scott-Elliot, and Withania somnifera (L.) Dunal. A literature search was conducted on the PubMed, Scopus, and Web of Science databases with the aim of identifying all the relevant articles published on the issue up to June 2020. Most of the selected sexual enhancers appeared to be safe at therapeutic doses, although mild to severe adverse effects may occur in cases of overdosing or self-medication with unstandardized products. Drug interactions are more concerning, considering that herbal aphrodisiacs are likely used together with other plant extracts and/or pharmaceuticals. However, few data are available on the side effects of several plants included in this review, and more clinical studies with controlled administrations should be conducted to address this issue.

Kratom (Mitragyna speciosa): worldwide issues

PURPOSE OF REVIEW

To inform readers about the increasingly popular Western dietary supplement, kratom (Mitragyna speciosa) and how the products are available in the Western world compared with traditional Southeast Asian use. Kratom has been traditionally used for increasing stamina of outdoor laborers (farmers), mood enhancement, pain, and opium addiction. Interestingly, kratom has been reported to have a paradoxical effect in that stimulant feelings, and sedative feelings can be obtained depending on the amount utilized. There are several biologically active alkaloids present in kratom.

RECENT FINDINGS

Recent studies have been focused on the interactions of mitragynine, the most abundant alkaloid, and opioid-like effects. This has been driven by the harm that kratom products have produced in the Western world, in stark contrast to the lack of harm in Southeast Asian traditional use over centuries. Many users in the Western world ingest kratom for mood enhancement and/or to ween themselves from prescription or illicit opioids. Highly concentrated products and recreational use and misuse have resulted in individuals pushing doses to levels that have not been imagined or ever studied in animal, let alone humans.

SUMMARY

Kratom, as a preparation and how it is utilized is different around the world.

Patterns and reasons for kratom (Mitragyna speciosa) use among current and former opioid poly-drug users

ETHNOPHARMACOLOGICAL RELEVANCE

Kratom (Mitragyna speciosa) is a native medicinal plant of Southeast Asia widely reported to be used to reduce opioid dependence and mitigate withdrawal symptoms. There is also evidence to suggest that opioid poly-drug users were using kratom to abstain from opioids.

AIM OF THE STUDY

To determine the patterns and reasons for kratom use among current and former opioid poly-drug users in Malaysia.

MATERIALS AND METHODS

A total of 204 opioid poly-drug users (142 current users vs. 62 former users) with current kratom use history were enrolled into this cross-sectional study. A validated UPLC-MS/MS method was used to evaluate the alkaloid content of a kratom street sample.

RESULTS

Results from Chi-square analysis showed that there were no significant differences in demographic characteristics between current and former opioid poly-drug users except with respect to marital status. Current users had higher odds of being single (OR: 2.2: 95%CI: 1.21-4.11; p < 0.009). Similarly, there were no significant differences in the duration (OR: 1.1: 0.62-2.03; p < 0.708), daily quantity (OR: 1.5: 0.85-2.82; p < 0.154) or frequency of kratom use between current and former opioid poly-drug users (OR: 1.1: 0.62-2.06; p < 0.680). While both current and former opioid users reported using kratom to ameliorate opioid withdrawal, current users had significantly higher likelihood of using kratom for that purpose (OR: 5.4: 95%CI: 2.81-10.18; p < 0.0001). In contrast, former opioid users were more likely to be using kratom for its euphoric (mood elevating) effects (OR: 1.9: 95%CI: 1.04-3.50; p < 0.035). Results from the UPLC-MS/MS analysis indicated the major alkaloids present in the representative kratom street sample (of approximately 300 mL of brewed kratom) were mitragynine, followed by paynantheine, speciociliatine and speciogynine, as well as low levels of 7-hydroxymitragynine.

CONCLUSIONS

Both current and former opioid poly-drug users regularly used kratom (three glasses or about 900 mL daily or the equivalent of 170.19 mg of mitragynine) to overcome opioid poly-drug use problems.

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.

Can Kratom (Mitragyna speciosa) Alleviate COVID-19 Pain? A Case Study

Among the symptoms of COVID-19 fever, general malaise, pain and aches, myalgia, fatigue, and headache can affect the quality of life of patients, even after the end of the acute phase of the infection and can be long lasting. The current treatment of these symptoms, also because COVID-19 patients have been asked not to use non-steroidal anti-inflammatory drugs (NSAIDs), in particular ibuprofen are often unsatisfactory. Among the above mentioned symptoms malaise and fatigue seem the most difficult to treat. In this case report we describe the use of kratom (Mitragyna speciosa) by a patient with confirmed COVID-19 infection. What we observed was a fast and sustained relieve of the above mentioned symptoms.

Self-Report Data on Regular Consumption of Illicit Drugs and HIV Risk Behaviors after Kratom (Mitragyna Speciosa korth.) Initiation among Illicit Drug Users in Malaysia

This study sought to determine the relationship between kratom (Mitragyna speciosa) initiation and regular consumption of illicit drugs and HIV risk behaviors in a cohort of illicit drug users in Malaysia. 260 illicit drug users with current kratom use were recruited through convenience sampling for this cross-sectional study. All were male, with the majority being Malays (95%, n = 246/260). Results suggest that kratom initiation was associated with significant decrease in the regular use of heroin (odds ratio (OR) = 0.50, 95% confidence interval (CI): 0.40- 0.72; p = .0001), methamphetamine (OR = 0.23, CI: 0.16- 0.35; p < .0001), and amphetamine (OR = 0.17, CI: 0.09- 0.34; p < .0001). Kratom initiation was also associated with reduction in regular HIV risk behaviors such as having sex with sex workers (OR = 0.20, CI: 0.12-0.32; p < .0001), using drugs before sexual intercourse (OR = 0.20, CI: 0.13- 0.31; p < .0001), injecting behaviors (OR = 0.10, CI: 0.04- 0.25; p < .0001), sharing of injection equipment (OR = 0.13, CI: 0.04- 0.43; p < .0001), and injecting with other injection drug users (IDUs) (OR = 0.07, CI: 0.02- 0.24; p < .0001).