The pharmacology and toxicology of kratom: from traditional herb to drug of abuse

Modulatory effects of Kratom extract on the gut microbiota of rats: implications for health

BACKGROUND

Kratom (Mitragyna speciosa), a plant native to Southeast Asia, is commonly used as a supplement for fatigue, pain relief, mood enhancement, and euphoria. Kratom extract exhibits diverse pharmacological properties, including antioxidant, anti-inflammatory, and gastrointestinal effects, with studies showing its ability to modulate gut microbiota and stimulate beneficial bacteria growth. Given these properties, kratom treatment may produce significant effects in a rat model, warranting further investigation.

METHODS

Male Wistar rats were administered kratom extract orally on a daily basis for 28 days. Fresh fecal samples were collected and analyzed for changes in gut microbiome composition using 16S rRNA sequencing. Hematological parameters and lipid profiles were also measured to evaluate any systemic effects.

RESULTS

The administration of kratom extract did not significantly affect hematological parameters or lipid profiles. However, notable changes were observed in gut microbiota composition, with significant increases in specific bacteria such as Candidatus Stoquefichus and Prevotellaceae UCG-001, and a decrease in Corynebacterium. LEfSe and cladogram analyses corroborated the higher prevalence of Candidatus Stoquefichus, Prevotellaceae UCG-001, and Erysipelatoclostridiaceae in the kratom treatment group compared to controls.

CONCLUSIONS

Kratom extract significantly alters gut microbiome composition in rats, promoting beneficial bacteria while also elevating certain taxa associated with negative health outcomes. These mixed effects highlight the need for further research on the long-term implications of kratom use for gut health and its broader health consequences, as well as potential therapeutic applications.

CLINICAL TRIAL NUMBER

Not applicable.

At least four groups of kratom consumers in the United States: latent-class analysis of motivations for kratom use

Background: Kratom is a plant with alkaloids acting at opioid, serotonergic, adrenergic, and other receptors. Consumers report numerous use motivations.Objectives: To distinguish subgroups of kratom consumers by kratom-use motivations using latent-class analysis.Methods: From July to November 2022, we utilized convenience sampling and surveyed regular kratom consumers (n = 395, 38.1 years (SD 11.2), 54.9% male, 81.3% White) regarding demographics, lifetime and past-year substance use and preferences, substance use disorder history, healthcare barriers, kratom-use motivations, and general health. We used latent-class analysis to identify subgroups by use motivation and calculated conditional probabilities (Pc) for variables in each class.Results: A four-class model best fit our data. The largest class (32.4%) was characterized by the use of kratom for self-treatment of chronic pain (Pc = .91). The smallest class (19.2%) also reported using kratom for self-treatment, but usually as a long-term replacement for other substances (Pc = .75). The other two classes (24.8% and 23.5%) reported using kratom for management of anxiety (Pc = .87-.95) and depressive symptoms (Pc = .61-.89) and for recreation (Pc = .56- .86). These were distinguished from one another by probability of at least moderate kratom use disorder (Pc = .17 vs. .53), with greater probability observed in the class with greater anxiety (Pc = .13 vs. .50) and depressive (Pc = .34 vs. .82) symptom severity and more likely recreational use motivation (Pc = .56 vs. .86).Conclusion: Kratom consumers can be classified by their use motivations. As with other psychoactive substances, the range of motivations is consistent with the range of likely effects. It is not yet clear whether some motivations might indicate the risk of problems.

Unveiling the Complexities of Medications, Substance Abuse, and Plants for Recreational and Narcotic Purposes: An In-Depth Analysis

The complexities surrounding the use of medications, substance abuse, and the recreational use of plants are multifaceted and warrant a comprehensive examination. This review highlights the complexities surrounding the consumption of chemical substances in excess or for non-medical purposes, obtained through legal prescriptions, over-the-counter purchases, or illicit means, with an emphasis on the predictive role of stressors and individual-level variables in the development of substance use disorders, as well as the influence of the regulatory environment on patterns of consumption. Additionally, the alarming escalation in the mortality rate associated with illicit drug and opioid overdoses is also underscored. The recreational use of prescription medications can lead to significant health risks, particularly when combined with other substances; therefore, the need for interventions and preventive measures to address substance abuse among various populations is imperative. Furthermore, novel insights on substance abuse addiction, exploring the neurobiological mechanisms underlying addiction, and discussing treatment approaches and interventions are elucidated. Advancements in technology for detecting substance abuse are also highlighted, displaying innovative tools for more effective identification and monitoring. In conclusion, the complexities of medications, substance abuse, and the recreational use of plants reveal a landscape marked by overlapping motivations and health implications. The distinction between medical and recreational use is critical for understanding user behavior and addressing public health concerns.

An exploratory study of the safety profile and neurocognitive function after single doses of mitragynine in humans

RATIONALE

Despite the growing scientific interest on mitragynine, the primary alkaloid in kratom (Mitragyna Speciosa), there is a lack of clinical trials in humans.

OBJECTIVES

This phase 1 study aimed to evaluate mitragynine's safety profile and acute effects on subjective drug experience, neurocognition, and pain tolerance.

METHODS

A placebo-controlled, single-blind, within-subjects study was conducted in two parts. In part A, eight healthy human volunteers received placebo and three doses of mitragynine (5, 10, and 20 mg) in a sequential dosing scheme, on separate days. In part B, a second group of seven volunteers received placebo and 40 mg of mitragynine. Vital signs, subjective drug experience, neurocognitive function, and pain tolerance were measured at regular intervals for 7 h after administration.

RESULTS

Overall, mitragynine did not affect most of the outcome measures at any dose. Yet, the lowest dose (5 mg) of mitragynine increased subjective ratings of arousal and attention, accuracy in a sustained attention task, and motor inhibition. The highest dose (40 mg) of mitragynine increased subjective ratings of amnesia and produced mild psychopathological symptoms. Mitragynine did not significantly affect vital signs, and only mild, transient side effects were reported.

CONCLUSION

The present study suggests that low doses (5-10 mg) of mitragynine may cause subjective feelings of stimulation and enhance attention, while the highest dose (40 mg) may cause inhibitory feelings of amnesia and distress. Mitragynine doses up to 40 mg were well tolerated in this group.

Mitragyna speciosa Korth toxicity: Experimental findings and future prospects

Mitragyna speciosa (Roxb.) Korth, locally known as kratom, is a traditional medicinal plant from Southeast Asia, with mitragynine as its principal alkaloid. Similar to other medicinal plants, kratom has side effects and toxicities, which have been documented in scientific studies and case reports. The mitragynine sale and possession of kratom are prohibited in Malaysia but legalized in Thailand. In the US, kratom is not lawfully marketed as a drug product, a dietary supplement, or a food additive in conventional food. Despite these restrictions, individuals continue to self-administer kratom to alleviate various health problems, often without a comprehensive understanding of the associated toxicities. Hence, the primary aim of this review is to provide a comprehensive overview of the toxicities associated with kratom, drawing from scientific studies, case reports, and other relevant sources. It also addresses the management of these toxicities, identifies gaps in existing studies, and discusses future perspectives. Therefore, a literature review search was conducted to gather essential information for this review. The in vitro studies focused on metabolizing enzymes, indirectly indicating kratom toxicity. By contrast, the in vivo results directly demonstrated kratom's toxic effects on the liver, kidneys, lungs, and brain. Case studies, primarily from Western countries, involved both single and combination use of kratom. Thus, by shedding light on these aspects, we aim to enhance awareness among healthcare professionals and the general public. Additionally, identifying existing gaps can guide future scientific studies. Since prevention is better than cure, this review holistically presents information about the toxicities associated with the use of kratom leaves, serving anyone seeking to understand and prevent kratom-related toxicities.

Binding characteristics of the major kratom alkaloid, mitragynine, towards serum albumin: Spectroscopic, calorimetric, microscopic, and computational investigations

Mitragynine (MTG) is a prominent indole alkaloid that is present abundantly in Mitragyna speciosa, commonly referred to as kratom. MTG has garnered significant attention due to its selective agonistic characteristics towards opioid receptors and related analgesic effects. In the circulatory system, the in vivo efficacy of MTG is dictated by its interaction with plasma proteins, primarily human serum albumin (HSA). In the present study, we utilized a broad methodology that included spectroscopic, calorimetric, microscopic, and in silico approaches to characterize the interaction between MTG and HSA. Alterations in the UV absorption spectrum of HSA by the presence of MTG demonstrated a ground-state complexation between the protein and the ligand. The Ka values obtained for the MTG-HSA interaction were in the range 103-104 M-1 based on analysis of fluorescence and ITC data, respectively, indicating an intermediate binding affinity. The binding reaction was thermodynamically favorable as revealed by ΔH, ΔS, and ΔG values of -16.42 kJ mol-1, 39.97 J mol-1 K-1, and -28.34 kJ mol-1, respectively. Furthermore, CD spectroscopy results suggested MTG binding induced minimal effects on the structural integrity of HSA, supported by computational methods. Changes in the dimensions of HSA particles due to aggregation, as observed using atomic force microscopy in the presence of MTG. Competitive drug displacement results seemingly suggested site III of HSA located at subdomain IB as the preferred binding site of MTG, but were in inconclusive. However, docking results showed the clear preference of MTG to bind to site III, facilitated by hydrophobic (alkyl and pi-alkyl) and van der Waals forces, together with carbon hydrogen bonds. Additionally, the MTG-HSA complexation was demonstrated to be stable based on molecular dynamics analysis. The outcomes of this study shed light on the therapeutic potential of MTG and can help in the design of more effective derivatives of the compound.

Kratom: A Narrative Review of the Possible Clinical Uses and Dangers of This Opioid-Like Plant

The term "kratom" refers to a plant species formally known as Mitragyna speciosa. Kratom is composed of over 40 alkaloids, a type of organic compound that contains nitrogen. These compounds work primarily via binding to opioid receptors expressed on neurons, where they stimulate signal transduction mechanisms involving the activation of G proteins. Kratom has been shown to cause both a stimulant-like effect and a sedative effect in humans. These studies have shown that use is highest among European-American, middle-class men living in suburban areas. Additionally, individuals who have a history of opioid misuse are also more likely to take kratom. Kratom is used by many different people in the US for numerous different reasons. Some of the most often cited reasons include treating chronic pain conditions, depression, and anxiety. Individuals who used kratom for these reasons typically consumed kratom daily at a dose of 1-3 grams, with the kratom extracted into a powder to be consumed in a capsule. Additionally, there have been reports of kratom being used to treat opioid withdrawal symptoms, as kratom can bind to some of the same receptors as opioids. This manuscript specifically describes trends regarding the use of kratom in the US, pharmacokinetic and pharmacodynamic properties of kratom, potential therapeutic uses of kratom, adverse events caused by kratom, and case studies in the literature regarding patients using kratom.

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.

Demographic and behavioral factors associated with kratom use among U.S. college students

Objective: Kratom use represents a growing risk for public health. The present study examined demographic and behavioral factors linked with kratom use. Participants: Participants were college students in the United States who participated in the 2019-2020 Healthy Minds Study. Methods: Participants completed survey-based assessment of kratom use and related demographic, behavioral, and mental health variables. Results: Kratom use was linked with being White, male or transgender/gender nonconforming, identifying as a sexual minority, use of alcohol or marijuana, and depressive symptoms. Kratom use was not uniquely linked to exercise or anxiety. Conclusions: The results of the present study can be used to inform initial targeting of efforts to reduce kratom use among college students.

Beneficial and adverse health effects of kratom (Mitragyna speciosa): A critical review of the literature

Used in Southeast Asia for generations, kratom gained popularity in the United States and elsewhere over the past several decades. Derived from Mitragyna speciosa, kratom preparations including leaves, teas, powders, capsules, and extracts may yield stimulant, analgesic, and opioid-like effects that occur dose-dependently based on concentrations of kratom's key alkaloids, mitragynine and 7-hydroxymitragynine. Such effects are responsible for kratom's potential as a reduced-harm alternative to opiates and as a withdrawal treatment. But these properties are also associated with tolerance development and addictive potential. Given mitragynine and 7-hydroxymitragynine activity on cytochrome P450 isoforms and opioid receptors, adverse effects among polysubstance users are a concern. Current literature on the toxicology of kratom is reviewed, including product alkaloid concentrations, in vitro and in vivo data, epidemiological evidence, and human case data. The potential harms and benefits of kratom products are discussed within an exposure assessment framework, and recommendations for industry are presented. Current evidence indicates that kratom may have therapeutic potential in some persons and that products present few risks with typical, non-polysubstance use. However, few studies identified alkaloid doses at which adverse effects were expected in humans or animals. Such research is needed to inform future assessments of kratom's risks and benefits.

Treatment of poppy seed tea misuse with buprenorphine in a telehealth practice: a case series

BACKGROUND

Poppy seed tea (PST) is a legally obtainable source of opiates made from the seeds of the opium poppy. Our large telehealth opioid use disorder (OUD) provider group has treated several patients with PST misuse.

METHODS

We retrospectively identified patients with primary PST use disorder treated with buprenorphine in a telehealth-only practice with first visits between January 2021 and December 2022. Patients were identified by having the word "poppy" in their enrollment note, and then charts were reviewed to determine which patients had primary PST misuse. Demographics, buprenorphine doses, and retention in treatment were recorded.

RESULTS

We identified 18 patients treated for PST use disorder. Fifteen (83.3%) identified as male, mean age was 40.4 (standard deviation 8.8) years, and patients resided in 10 different U.S. states. Median starting buprenorphine dose was 2 mg (interquartile range (IQR) 2-2.5 mg). Median stabilizing dose of buprenorphine was 16 mg daily (IQR 15-20.5 mg). As of June 2023, 5 patients (27.8%) were still in active treatment. Two patients (11.1%) had completed a planned, elective taper. Ten patients (55.6%) had unplanned discontinuation from treatment, and 3 patients (16.7%) discontinued for other reasons.

CONCLUSIONS

To our knowledge, this is the largest case series describing PST misuse in the U.S., and the first to demonstrate its treatment in the telehealth setting. PST use disorder is treatable with buprenorphine with doses similar to treatment of other opioid use disorders. Clinicians who treat patients with OUD should be aware of PST use disorder and its treatment.

Characterization of kratom use and knowledge at a rural, Oregon community health center

BACKGROUND

Kratom is an herbal supplement that has drawn attention for its use in the self-treatment of opioid withdrawal, and its widespread availability with minimal restrictions. Past Web-based research has attempted to determine patterns and trends of use, but generalizability to underserved populations is unclear.

OBJECTIVE

The purpose of this study was to characterize behavior related to kratom, attitudes toward kratom, and knowledge of kratom in a rural, underserved population.

METHODS

We developed, refined, and administered a cross-sectional, 36-item survey to examine use, attitudes, and knowledge of kratom. We recruited participants and administered the survey alongside medical office appointments between January and April 2023. Data were summarized using descriptive statistics.

RESULTS

A convenient sample of 186 patients (of the 907-patient clinic panel) were invited to participate and 150 returned the survey. Most patients were female (52.0%) and white (86.6%), and approximately half had an income below the federal poverty level (48.5%). Seventeen participants reported previous experience with kratom use, with one actively using kratom. The most commonly reported reasons for use were pain (47.1%) and mental health (41.2%). Kratom knowledge was low regardless of kratom use history, with most respondents correctly answering between 1 and 3 questions (n = 71 of 86; 82.3%) of the 5 knowledge-focused items.

CONCLUSION

Results suggest that although active kratom use is uncommon in this Oregon population, 1 in 10 surveyed had used kratom. Regardless of past use, respondents had limited knowledge of kratom. Future research should focus on understanding trends in kratom use behaviors in underserved populations, addressing patient knowledge gaps, and evaluating patient safety and health equity implications.

[Kratom-From natural remedy to addictive drug and back]

BACKGROUND

Kratom/ketum is a psychoactive herbal preparation that has been used for a long time as a remedy and performance-enhancing substance in Southeast Asia. The advancement of globalization is making kratom increasingly more available in the western world, where it is becoming increasingly more used.

OBJECTIVE

The current research on kratom and its ingredients is presented.

MATERIAL AND METHODS

An overview of the use and effects of kratom is exemplary given on the basis of reports. The instrumentalization of the drug and its consequences up to the development of addiction are discussed.

RESULTS

Consumption is accompanied by several instrumentalizeable effects so that kratom is used as a therapeutic substance in the self-management of pain, anxiety and depression as well as other substance addictions. Another benefit comes from the performance-enhancing effects on physical work and in a social context. Consumption is usually well controlled, rarely escalates and has few and mostly mild aversive side effects. The danger arises from consumption particularly when there is an escalation of the dose and from mixed consumption with other psychoactive substances. The main alkaloid mitragynine and the more potent 7‑hydroxy-mitragynine are considered mainly responsible for the effect. Both have a complex pharmacology that involves partial µ‑opioid receptor agonism.

DISCUSSION

Epidemiological, clinical and neurochemical studies have shown that kratom only has a limited addictive drug profile, which might suggest a medical use as a remedy or substitute in addiction treatment.

A review on Mitragyna speciosa (Rubiaceae) as a prominent medicinal plant based on ethnobotany, phytochemistry and pharmacological activities

Mitragyna speciosa Korth (kratom) is a tropical indigenous tree of Southeast Asia. It is commonly consumed by the people due to its various pharmacological properties. The leaves of this plant are traditionally used for the treatment of several diseases including pain, fever, cough, anxiety, depression, obesity, diarrhoea, wound healing, diabetes, hypertension as well as for the prevention of cancer and improvement of sexual performance. Phytochemical investigations have confirmed the presence of more than forty alkaloids along with the presence of other bioactive secondary metabolites. Among the alkaloids isolated, mitragynine and 7-hydroxymitragynine along with their derivatives have been widely evaluated and reported to possess various pharmacological effects. Hence, the aim of this review is to shed light on the traditional uses of kratom and the scientific studies to justify the folkloric claims and active principles responsible for the various medicinal effects associated with the leaves of this plant. This review highlights the potential benefits and toxicities associated with M. speciosa leaves along with the phytochemistry. Moreover, the existing gaps in the field of M. speciosa study have been identified along with the future directions to further avail the benefits of this plant species.

The prevalence of kratom use and association with co-occurring substance use among adolescents: a 2022 Bangkok behavioral surveillance survey, Thailand

Thailand removed kratom from the list of prohibited substances in 2021, possession and consumption of Kratom is now legal. It is prohibited from selling Kratom to anyone under the age of 18 and/or who is pregnant or breastfeeding. While there are benefits from kratom use with few 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. We utilized data from the Behavior Surveillance Survey in Bangkok (n = 5,740) to examine the use of kratom with other substances use in the 12 months before the survey. The prevalence of past-year kratom use among students was 9.3% (95%CI = 8.7-9.9), with higher proportions of males (12.4 versus 6.1%, p < 0.001). The factors associated with past 12-month kratom use were academic performance (Medium GPA; AOR = 2.41, 95% CI = 1.76-3.29; Low GPA; AOR = 4.15, 95% CI = 2.94-5.87), close friend use substance (AOR = 1.94, 95% CI = 1.44-2.59), cannabis use (AOR = 6.84, 95% CI = 4.61-10.15), consumed alcohol (AOR = 2.32, 95% CI = 1.77-3.02), smoked conventional cigarettes (AOR = 4.20, 95% CI = 3.16-5.58), used e-cigarettes (AOR = 4.37, 95% CI = 3.30-5.79) used illicit opioids (AOR = 8.13, 95% CI = 4.35-15.18), and other illicit drug use (AOR = 9.15, 95% CI = 3.78-22.14). These findings may be useful for the initial targeting of efforts to reduce adolescent consumption of kratom. Future studies should examine the effect of regulatory policies or other Thai FDA-related policies use of illicit drugs and e-cigarettes on kratom use.

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 as a potential substance use disorder harm reduction agent

Substance use disorders contribute to considerable U.S. morbidity and mortality. While effective pharmacotherapy options are available to treat opioid and alcohol use disorders, for a variety of reasons, many patients lack access to treatment or may be reluctant to seek care due to concerns such as perceived stigma or a current lack of desire to completely curtail their substance use. Furthermore, treatment options are limited for patients with stimulant or polysubstance use disorders. Thus, there is considerable need to expand the substance use disorder harm reduction armamentarium. Kratom (Mitragyna speciosa Korth.) is an herbal substance that can produce both opioid and stimulant-like effects, and its use in the US is growing. Though there are concerns regarding adverse effects, dependence risk, and limited regulation of its manufacturing and sale, the pharmacology of kratom and early preclinical studies suggest a potential role as a harm reduction agent for various substance use disorders, and it has historically been used in Southeast Asia for such purposes. The goal of this review is to describe kratom's history of use, pharmacology, and early pre-clinical and observational research regarding its therapeutic potential in opioid use disorder, as well as alcohol, stimulant, and polysubstance use disorders, while also highlighting current concerns around its use, existing gaps in the literature, and directions for future research.

The Complexities of Kratom: Insights on an Increasingly Frequent Clinical Encounter

Mitragyna speciosa (kratom) is a tropical tree native to Southeast Asia with dose-dependent stimulant and opioid properties. Kratom has garnered attention due to its increasing popularity and potential for dependence, tolerance, and withdrawal. We report the case of a 72-year-old man admitted to the hospital for a deep vein thrombosis and obstructive uropathy who began experiencing kratom withdrawal. He experienced less cravings and improvement in withdrawal symptoms with buprenorphine-naloxone 8 mg/2 mg daily. Notably, our case highlights kratom's contributions to a medically complex presentation and potential kratom-drug interactions due to its posited inhibitory effect on cytochrome P450 enzymes and P-glycoprotein. Our case adds to the growing literature which describes buprenorphine-naloxone as an effective treatment for kratom dependence and withdrawal.

Effects of Itraconazole on Pharmacokinetics of Mitragynine and 7-Hydroxymitragynine in Healthy Volunteers

CYP3A4-mediated metabolic conversion of mitragynine to 7-hydroxymitragynine (7OH) has been demonstrated in human liver microsomes, and in rodents. Pharmacokinetics (PK) of mitragynine and 7OH in humans is still limited. We aimed to examine the pharmacokinetics of mitragynine and the formation of 7OH in healthy volunteers. To elucidate involvement of CYP3A4 in 7OH formation, inhibition by itraconazole was implemented. Two study periods with PK study of mitragynine alone in period 1, followed by period 2 including itraconazole pretreatment was conducted. Freshly prepared kratom tea consisting of 23.6 mg of mitragynine was given to participants in both study periods. Serial blood samplings were performed for 72 hours, and analyzed using a validated LCMS in multiple reaction monitoring mode. The median Cmax for mitragynine of 159.12 ± 8.68 ng/mL was attained in 0.84 h. While median Cmax for 7OH of 12.81 ± 3.39 ng/mL was observed at 1.77 h. In period 1, Cmax and AUC 0-inf of 7OH accounted for 9% and 20 %, respectively, of those parameters for mitragynine. The geometric mean ratio of AUC0-72 for 7OH/mitragynine (metabolic ratio, MR) was 13.25 ± 1.07. Co-administration of itraconazole 200 mg per day orally for 4 days (period 2) decreased 7OH exposure by 56% for Cmax and 43% for AUC0-72 after a single oral dose of kratom tea. While the Cmax of mitragynine increased by 1.5 folds without a significant change in Tmax. The geometric mean metabolic ratio was 3.30 ± 1.23 (period 2), indicating the attenuation for the formation of 7OH by the pretreatment with itraconazole. This suggested the CYP3A4-mediated formation of 7OH from mitragynine in healthy volunteers. This study provides the first evidence of metabolic conversion of mitragynine to 7OH in humans.

Screening and confirmation of psilocin, mitragynine, phencyclidine, ketamine and ketamine metabolites by liquid chromatography-tandem mass spectrometry

A safe and productive workplace requires a sober workforce, free from substances that impair judgment and concentration. Although drug monitoring programs already exist, the scope and loopholes of standard workplace testing panels are well known, allowing other substances to remain a source of risk. Therefore, a high-throughput urine screening method for psilocin, mitragynine, phencyclidine, ketamine, norketamine and dehydronorketamine was developed and validated in conjunction with a urine and blood confirmation method. There are analytical challenges to overcome with psilocin and mitragynine, particularly when it comes to drug stability and unambiguous identification in authentic specimens. Screening and confirmation methods were validated according to the American National Standards Institute/Academy Standards Board (ANSI/ASB) Standard 036, Standard Practices for Method Validation in Forensic Toxicology. An automated liquid handling system equipped with dispersive pipette extraction tips was utilized for preparing screening samples, whereas an offline solid-phase extraction method was used for confirmation sample preparation. Both methods utilized liquid chromatography-tandem mass spectrometry to achieve limits of detection between 1-5 ng/mL for the screening method and 1 ng/mL for the confirmation method. Automation allows for faster throughput and enhanced quality assurance, which improves turnaround time. Compared to previous in-house methods, specimen volumes were substantially decreased for both blood and urine, which is an advantage when volume is limited. This screening technique is well suited for evaluating large numbers of specimens from those employed in safety-sensitive workforce positions. This method can be utilized by workplace drug testing, human performance and postmortem laboratories seeking robust qualitative screening and confirmation methods for analytes that have traditionally been challenging to routinely analyze.

Presence of kratom in opioid overdose deaths: findings from coroner postmortem toxicological report

Background

Kratom (Mitragyna speciosa) use in the United States is becoming increasingly popular and its legal status varies widely from state to state. Multiple reports of adverse events associated with kratom use have ranged from liver injury, seizures, psychiatric disturbance, and rarely death.

Methods

This study investigated coroner autopsy reports from Kern County in California for the year 2020 which included qualitative data on substances from blood toxicological reports. Of the 214 opioid-associated accidental overdoses reported, 4 subjects (1.9%) had mitragynine (kratom) exposure on the autopsy report and were included in the study. We reported available demographic information and comorbid substance findings from the associated autopsy reports.

Results

All 4 individuals with mitragynine (kratom) toxicology had accidental opioid overdose deaths noted in autopsy reports. Each subject also had toxicology positive for at least one other substance. Fentanyl was found in 3 (75%) of the cases and suspected to be the primary contributor to opioid-related deaths in those cases. However, one fatality was without fentanyl, but instead had tested positive for benzodiazepines, cannabis, and other psychiatric medications.

Discussion

The findings of this brief report provide insight into the role that mitragynine (kratom) may have in modulating risk of opioid-related deaths. The combined use of kratom with opioids such as fentanyl appears most likely to increase the risk of a fatal overdose, but it may also occur with other medications such as benzodiazepines and psychiatric medications. It is a serious concern that in the midst of the opioid overdose epidemic there is a growing presence of kratom use in the U.S. population with a largely unregulated status.

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.

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): a Psychoactive Plant with Opportunities and Risks]

Kratom is an evergreen tree that is native to Southeast Asia. Its leafs are traditionally used as a stimulant, a remedy for various health problems and for religious purposes. Especially in the US (in a lesser extent also in Europe) kratom use is significantly prevalent. In Western countries, kratom is used predominantly as an analgesic and stimulant, for the treatment of opioid use disorders, and for improving mental health (e. g., in depression, anxiety disorders). Main molecular constituents of kratom are alkaloids of which mitragynine and 7-hydroxymitragynine appear to be most important. Pharmacodynamics and -kinetics of kratom are complex and insufficiently studied. It is known that mitragynine and 7-hydroxymitragynine are partial agonist at human μ-opioid receptors and antagonists at κ- and δ-opioid receptors with additional effects at other central receptors. Tolerability of kratom is presumably better than that of classical opioids; this is probably due to missing effects of kratom on β-arrestin and discussed as a starting point for the development of opioids with improved tolerability. Some alkaloids of kratom are inhibitors of CYP26 and to a somewhat lesser degree of CYP2C19 and CYP3A4. The addictive potential of kratom appears to be lower than that of classical opioids; however, corresponding data is limited and kratom use disorders appear to occur primarily in Western countries. Several cases of severe health-related problems and deaths are known in the US; in these cases, however, polysubstance use was usually present. Kratom use is likely associated with hepatotoxicity and cardiotoxicity. Kratom-associated mortality and morbidity in Western countries are quantitatively significantly different from Southeast Asia, where kratom use is no public health problem. The reasons for this may be the combined use of substances (which is more prevalent in Western countries), higher dosages of consumed kratom, adulterations and contaminations of commercially available kratom in Western countries, pharmacokinetic interactions, and higher concentrations of 7-hydroxymitragynine in dried kratom leafs (that are typically consumed in Western countries) in comparison to fresh leafs (that are typically consumed in Southeast Asia).

A Critical Review of the Neuropharmacological Effects of Kratom: An Insight from the Functional Array of Identified Natural Compounds

Kratom (Mitragyna speciosa Korth. Havil) has been considered a narcotic drug for years, barred by the law in many parts of the world, while extensive research over the past few decades proves its several beneficial effects, some of which are still in ambiguity. In many countries, including Thailand, the indiscriminate use and abuse of kratom have led to the loss of life. Nonetheless, researchers have isolated almost fifty pure compounds from kratom, most of which are alkaloids. The most prevalent compounds, mitragynine and 7-hydroxy mitragynine, are reported to display agonist morphine-like effects on human μ-opioid receptors and antagonists at κ- and δ-opioid receptors with multimodal effects at other central receptors. Mitragynine is also credited to be one of the modulatory molecules for the Keap1-Nrf2 pathway and SOD, CAT, GST, and associated genes' upregulatory cascades, leading it to play a pivotal role in neuroprotective actions while evidently causing neuronal disorders at high doses. Additionally, its anti-inflammatory, antioxidative, antibacterial, and gastroprotective effects are well-cited. In this context, this review focuses on the research gap to resolve ambiguities about the neuronal effects of kratom and demonstrate its prospects as a therapeutic target for neurological disorders associated with other pharmacological effects.

The Great Imitator: A Case of Accidental Kratom Overdose

Kratom (Mitragyna speciosa) is an herb that is sold over the counter in both pill and liquid forms. It contains opioid and stimulant properties and is used for relaxation as well as for weaning off opioid addictions. While a few adverse effects of kratom have been already reported, mainly with concerns around its toxicity, very little is known about it. We report a case of a female in her 40s presenting with signs of hypoxia reversed with naloxone administration, initially suspected to be a case of opioid overdose. Upon becoming alert and oriented, the patient and her husband reported that she consumed a large amount of kratom bought from the local gas station, and he later noticed that her lips were turning blue and she was becoming increasingly altered. Her urine toxicology was noted to be negative for opioids or any other substance use. The patient survived this accidental overdose due to the quick action of her husband, who rushed her to the emergency department (ED) upon realizing she appeared altered and very ill. It is important for emergency medicine practitioners to be aware of kratom overdose as a possible item on the differential diagnosis. This paper focuses on kratom overdose presentation and treatment.

Translating Kratom-Drug Interactions: From Bedside to Bench and Back

Kratom is a botanical natural product belonging to the coffee family, with stimulant effects at low doses and opioid-like effects at higher doses. During the last two decades, kratom has been purported as a safer alternative to pharmaceutical and illicit drugs to self-manage pain and opioid withdrawal symptoms. Kratom alkaloids, typically mitragynine, have been detected in biologic samples from overdose deaths. These deaths are often observed in combination with other drugs and are suspected to result from polyintoxications. This review focuses on the potential for kratom to precipitate pharmacokinetic interactions with object drugs involved in these reported polyintoxications. The legal status, chemistry, pharmacology, and toxicology are also summarized. The aggregate in vitro and clinical data identified kratom and select kratom alkaloids as modulators of cytochrome P450 (P450) enzyme activity, notably as inhibitors of CYP2D6 and CYP3A, as well as P-glycoprotein-mediated efflux activity. These inhibitory effects could increase the systemic exposure to co-consumed object drugs, which may lead to adverse effects. Collectively, the evidence to date warrants further evaluation of potential kratom-drug interactions using an iterative approach involving additional mechanistic in vitro studies, well designed clinical studies, and physiologically based pharmacokinetic modeling and simulation. This critical information is needed to fill knowledge gaps regarding the safe and effective use of kratom, thereby addressing ongoing public health concerns. SIGNIFICANCE STATEMENT: The botanical kratom is increasingly used to self-manage pain and opioid withdrawal symptoms due to having opioid-like effects. The legal status, chemistry, pharmacology, toxicology, and drug interaction potential of kratom are reviewed. Kratom-associated polyintoxications and in vitro-in vivo extrapolations suggest that kratom can precipitate pharmacokinetic drug interactions by inhibiting CYP2D6, CYP3A, and P-glycoprotein. An iterative approach that includes clinical studies and physiologically based pharmacokinetic modeling and simulation is recommended for further evaluation of potential unwanted kratom-drug interactions.

Clinical Presentations and Treatment of Phenibut Toxicity and Withdrawal: A Systematic Literature Review

OBJECTIVES

This systematic review aimed to identify published articles that evaluated all phenibut toxicity and withdrawal cases to understand better their clinical presentations and treatments.

METHODS

A comprehensive literature search was conducted using Medline (Ovid), Embase (Ovid), and Cochrane Library databases to capture all published cases on the presentations and management of phenibut toxicity or withdrawal.

RESULTS

Sixty-two cases from 36 studies on presentation and management of phenibut toxicity or phenibut withdrawal were identified. Of all subjects, 80.7% were male. The average age was 30.9 years (SD, 13.2 years; range, 0-71 years). A total of 86.8% reported obtaining phenibut online, and 63.2% reported concomitant substance use with other addictive agents; benzodiazepines and alcohol were the most combined drugs. The average length of hospital stay was 5.0 days (n = 25; SD, 5.4 days; range, 1-25 days) for phenibut toxicity and 7.7 days (n = 20; SD, 7.8 days; range, 0-30 days) for phenibut withdrawals. The most common symptoms reported during phenibut toxicity were altered mental status, somnolence, psychosis, and movement disorders. Of the phenibut toxicity cases, 48.7% required intubation. Benzodiazepines and antipsychotics were most used to treat phenibut toxicity. For phenibut withdrawal cases, 95.7% reported daily use. The most common symptoms reported during phenibut withdrawals were anxiety, irritability or agitation, insomnia, and psychosis. Sixteen (69.6%) of phenibut withdrawal cases required multiple medications for treatment. Benzodiazepines, baclofen, atypical antipsychotics, gabapentanoids, and barbiturates were commonly used to treat phenibut withdrawals.

CONCLUSIONS

The seriousness of presentations, combined with the assortments of medications used for both syndromes, reflects the potential dangers of phenibut use and the need for systematized treatment protocols.

Pharmacokinetic and Pharmacodynamic Consequences of Cytochrome P450 3A Inhibition on Mitragynine Metabolism in Rats

Mitragynine, an opioidergic alkaloid present in Mitragyna speciosa (kratom), is metabolized by cytochrome P450 3A (CYP3A) to 7-hydroxymitragynine, a more potent opioid receptor agonist. The extent to which conversion to 7-hydroxymitragynine mediates the in vivo effects of mitragynine is unclear. The current study examined how CYP3A inhibition (ketoconazole) modifies the pharmacokinetics of mitragynine in rat liver microsomes in vitro. The study further examined how ketoconazole modifies the discriminative stimulus and antinociceptive effects of mitragynine in rats. Ketoconazole [30 mg/kg, oral gavage (o.g.)] increased systemic exposure to mitragynine (13.3 mg/kg, o.g.) by 120% and 7-hydroxymitragynine exposure by 130%. The unexpected increase in exposure to 7-hydroxymitragynine suggested that ketoconazole inhibits metabolism of both mitragynine and 7-hydroxymitragynine, a finding confirmed in rat liver microsomes. In rats discriminating 3.2 mg/kg morphine from vehicle under a fixed-ratio schedule of food delivery, ketoconazole pretreatment increased the potency of both mitragynine (4.7-fold) and 7-hydroxymitragynine (9.7-fold). Ketoconazole did not affect morphine's potency. Ketoconazole increased the antinociceptive potency of 7-hydroxymitragynine by 4.1-fold. Mitragynine (up to 56 mg/kg, i.p.) lacked antinociceptive effects both in the presence and absence of ketoconazole. These results suggest that both mitragynine and 7-hydroxymitragynine are cleared via CYP3A and that 7-hydroxymitragynine is formed as a metabolite of mitragynine by other routes. These results have implications for kratom use in combination with numerous medications and citrus juices that inhibit CYP3A. SIGNIFICANCE STATEMENT: Mitragynine is an abundant kratom alkaloid that exhibits low efficacy at the μ-opioid receptor (MOR). Its metabolite, 7-hydroxymitragynine, is also an MOR agonist but with higher affinity and efficacy than mitragynine. Our results in rats demonstrate that cytochrome P450 3A (CYP3A) inhibition can increase the systematic exposure of both mitragynine and 7-hydroxymitragynine and their potency to produce MOR-mediated behavioral effects. These data highlight potential interactions between kratom and CYP3A inhibitors, which include numerous medications and citrus juices.

Exploring adolescents' practice and perspective on the use and misuse of kratom in northwest Malaysia

Kratom is a plant homogenous to Southeast Asia with a long history of traditional use as medicinal herbs. However, recent years have witnessed its pervasive infiltration into international audience with growing public health concern. This cross-sectional study was conducted from 1 August 2017 till 31 August 2018 aiming to explore the practice and perspectives of kratom use and misuse among adolescents in northwest Malaysia. The study involved a self-administered questionnaire that was designed for the purpose of the study. The instrument had undergone prior validation process with a good overall internal reliability for the knowledge domain (Cronbach's alpha = 0.728) and attitude domain (Cronbach's alpha = 0.700). The questionnaire was distributed to 135 respondents involving adolescents aged 13 to 19 years old via convenience (non-kratom user) and snowball sampling (kratom users). There were 65 (47.8%) kratom users, while 70 (51.5%) were kratom-naïve. Among the kratom users, peer influence was the most common reason for them to be first involved with kratom, 26 (41.3%) whereas the reasons for kratom use quoted were to improve physical stamina, 10 (16.4%), as painkiller, 9 (14.8%), and to be accepted by peers, 7 (11.5%). Multiple logistic regression found that older age (95% CI: 0.13, 0.58; p = 0.001) and being active smokers (95% CI: 39.33, 980.63; p < 0.001) significantly predict kratom use among adolescents. The emerging trend of kratom abuse and misuse especially among the younger generation in Malaysia is raising concern and warrants social and governmental vigilance.

Narrative Review of Kratom, an Emerging Psychoactive Substance With Perianesthetic Implications

Opioid overprescribing, with resultant overdose and death, has led to a national focus on alternative treatments for pain. With the decline in legal access to opioids, kratom has gained popularity as a legal, "natural," and easily accessible nonprescription analgesic for consumers wishing to self-medicate for pain, opioid use disorder, and other mental health conditions. While implications of kratom use in patients with chronic pain and/or opioid use disorder have been published, information on perianesthetic implications is lacking. Anesthesiologists should be informed about kratom, including the potential for unexpected physiologic derangements and adverse drug interactions resulting from complex pharmacologic activity, cytochrome P450 interactions, and common adulterations of the drug that may result in unpredictable clinical effects. This article explores the relevance of kratom to perioperative anesthetic care, including suggestions for anesthesiologists extrapolated from published information in nonoperative settings that may improve patient safety in individuals using kratom.

Controversial usages of kratom (Mitragyna speciosa): For good or for evil

Kratom (Mitragyna speciosa) is a plant that grows well in tropical climates such as in Southeast Asia. Traditionally, people discovered it possessed a stimulating effect that relieved tiredness. Furthermore, it contains analgesic and medicinal properties for the treatment of pain, diarrhea, muscle discomfort, and blood pressure and to enhance stamina. Nevertheless, long term or regular consumption of kratom leads to addiction. This is because the main alkaloid of kratom, mitragynine, binds to opioid receptors and exerts a euphoric effect similar to that of morphine, which may lead to death. Due to this reason, kratom has been listed as a regulated substance in many countries including the United States, Thailand, Malaysia, Bhutan, Finland, Lithuania, Denmark, Poland, Sweden, Australia, and Myanmar. Usages of kratom carry two pharmacological effects depending on dosage. Low-dose kratom exerts a stimulating effect that refreshes the user. High-dose kratom exerts sedative effects that can lead to addiction similar to that of morphine. Despite the euphoric effect of kratom, the beneficial values of kratom to human health is indisputable. Therefore, a complete banning of kratom may cause a loss to pharmaceutical industry. Rather, a controlled or selective usage of kratom will be a better choice.

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.

A Multiple-Serotype Outbreak of Salmonella Infections Linked to Kratom, United States, 2017-2018

In early 2018, we investigated a large national multiple-serotype Salmonella outbreak linked to contaminated kratom, a raw minimally processed botanical substance. Kratom is a plant consumed for its stimulant effects and as an opioid substitute. A case was defined as a laboratory-confirmed Salmonella infection with one of the outbreak strains (serotypes I 4,[5],12:b:-, Heidelberg, Javiana, Okatie, Weltevreden, or Thompson) with illnesses onset during January 11, 2017-May 8, 2018. State and local officials collected detailed information on product consumption and sources. Suspected products were tested for Salmonella and traceback was conducted to determine product distribution chains and suppliers. We identified 199 cases from 41 states; 54 patients were hospitalized. Early interviews indicated kratom was an exposure of interest. Seventy-six (74%) of 103 people interviewed reported consuming kratom in pills, powders, or teas. Multiple serotypes of Salmonella were detected in samples of kratom collected from the homes of the patients and from retail locations. Several companies issued recalls of kratom products due to Salmonella contamination. To the authors' knowledge, this investigation is the first to establish kratom as a vehicle for Salmonella infection. Our findings underscore the serious safety concerns regarding minimally processed botanical substances intended for oral consumption and the challenges in investigating outbreaks linked to novel outbreak vehicles.

Public Health Implications and Possible Sources of Lead (Pb) as a Contaminant of Poorly Regulated Kratom Products in the United States

Kratom (Mitragyna speciosa) is a tropical tree that is indigenous to Southeast Asia. Kratom leaf products have been used in traditional folk medicine for their unique combination of stimulant and opioid-like effects. Kratom is being increasingly used in the West for its reputed benefits in the treatment of pain, depression, and opioid use disorder (OUD). Recent studies from the United States Food and Drug Administration (FDA, Silver Spring, MD, USA) and our laboratory have shown that many kratom products being sold in the United States are contaminated with potentially hazardous levels of lead (Pb). In this commentary, we discuss the public health implications of the presence of Pb in kratom products, particularly as they relate to the predicted levels of Pb exposure among kratom users. We also considered the specific toxic effects of Pb and how they might relate to the known physiologic and toxicologic effects of kratom. Finally, we consider the possible sources of Pb in kratom products and suggest several areas for research on this issue.

Exploring the self-reported motivations of kratom (Mitragyna speciosa Korth.) use: a cross-sectional investigation

Background: Kratom (Mitragyna speciosa Korth.) use outside of Southeast Asia has increased over the past decade. Objectives: This investigation clarifies kratom's role in perceived well-being, overall health, and temporal correlation with drug use to understand kratom's role in the self-treatment of substance use disorders (SUDs). Methods: Between July 2019 and July 2020 an anonymous, cross-sectional, online survey was taken by 7,381 people who use kratom (PWUK) recruited through social media and other online resources. This included an assessment of (a) the relationship between self-reported overall health, concomitant use of drugs of misuse, and demographics; (b) the perceived effectiveness of kratom in self-treating diagnosed health conditions or symptoms; (c) the profile of PWUK primarily for drug dependence, pain, and mood or mental health conditions based on demographics. Results: A total of 5,152 valid responses (45.9% females/53.7% males) were collected. Kratom was primarily used for self-treating pain (73.0%) and improving emotional or mental health conditions (42.2%) without clinical supervision. Those with a SUD (synthetic opioids, methadone, benzodiazepines, or heroin) used kratom after discontinuing illicit or other drugs (94.8%). The primary substances taken before or concomitantly with kratom were cannabis, cannabidiol, benzodiazepines, or kava. PWUKs report a dose-dependent benefit for alleviating pain and relieving negative moods. Adverse effects were primarily gastrointestinal, typically at high (>5 g/dose) and frequent (>22 doses/week) dosing. Conclusions: Kratom was primarily used as a harm-reduction agent for SUDs and self-treatment of chronic conditions. Healthcare professionals need better information about kratom, its potential adverse effects, and clinically significant drug interactions.

Kratom (Mitragyna speciosa)-Induced Hepatitis

Kratom is a plant with opioid-like properties known to produce stimulant and analgesic effects. Although there are numerous studies on the psychoactive components of kratom, less is known about the toxicity. Specifically, few reports describe kratom-induced hepatotoxicity and demonstrate histological features. We provide a case report detailing the clinicopathologic findings of drug-induced liver injury caused by kratom. The laboratory workup included significant elevation of total bilirubin and alkaline phosphatase. Liver biopsy demonstrated a prominent canalicular cholestatic pattern, mixed portal inflammation, and newly described perivenular necrosis. This report provides additional information on kratom toxicity because its use continues to rise.

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.

Current Understanding of the Effects and Potential Clinical Utility of Kratom: A Review

OBJECTIVE

The increasingly widespread use of kratom in the United States has raised concerns about its safety as well as spurring research into potential applications of its active ingredients in medical treatments.

METHODS

We reviewed the literature published over the past 20 years, including peer-reviewed publications and data released by United States government health agencies to provide an overview of this topic.

RESULTS

A variety of potentially beneficial and adverse effects of kratom use related to its opioid and stimulant properties have been documented, including addiction and withdrawal. Preliminary research in animals and case reports in humans have suggested medical utility for kratom in treating alcohol and opioid use disorders, pain, depression, and anxiety. However, the lack of controlled, standardized studies limits the clinical utility of this agent and is a barrier to safe consumption.

CONCLUSIONS

Historically, kratom has been used for medical purposes and for the treatment of alcohol and substance use disorders. The currently available literature suggests a potential for similar clinical applications. However, without controlled research studies or regulation, kratom poses numerous health risks to consumers.

Kratom Abuse Potential 2021: An Updated Eight Factor Analysis

Drugs are regulated in the United States (US) by the Controlled Substances Act (CSA) if assessment of their abuse potential, including public health risks, show such control is warranted. An evaluation via the 8 factors of the CSA provides the comprehensive assessment required for permanent listing of new chemical entities and previously uncontrolled substances. Such an assessment was published for two kratom alkaloids in 2018 that the Food and Drug Administration (FDA) have identified as candidates for CSA listing: mitragynine (MG) and 7-hydroxymitragynine (7-OH-MG) (Henningfield et al., 2018a). That assessment concluded the abuse potential of MG was within the range of many other uncontrolled substances, that there was not evidence of an imminent risk to public health, and that a Schedule I listing (the only option for substances that are not FDA approved for therapeutic use such as kratom) carried public health risks including drug overdoses by people using kratom to abstain from opioids. The purpose of this review is to provide an updated abuse potential assessment reviewing greater than 100 studies published since January 1, 2018. These include studies of abuse potential and physical dependence/withdrawal in animals; in-vitro receptor binding; assessments of potential efficacy treating pain and substance use disorders; pharmacokinetic/pharmacodynamic studies with safety-related findings; clinical studies of long-term users with various physiological endpoints; and surveys of patterns and reasons for use and associated effects including dependence and withdrawal. Findings from these studies suggest that public health is better served by assuring continued access to kratom products by consumers and researchers. Currently, Kratom alkaloids and derivatives are in development as safer and/or more effective medicines for treating pain, substances use disorders, and mood disorders. Placing kratom in the CSA via scheduling would criminalize consumers and possession, seriously impede research, and can be predicted to have serious adverse public health consequences, including potentially thousands of drug overdose deaths. Therefore, CSA listing is not recommended. Regulation to minimize risks of contaminated, adulterated, and inappropriately marketed products is recommended.

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.

Mitragynine improves cognitive performance in morphine-withdrawn rats

RATIONALE

The treatment of opiate addiction is an unmet medical need. Repeated exposure to opiates disrupts cognitive performance. Opioid substitution therapy, with, e.g., methadone, may further exacerbate the cognitive deficits. Growing evidence suggests that mitragynine, the primary alkaloid from the Kratom (Mitragyna speciosa) leaves, may serve as a promising alternative therapy for opiate addiction. However, the knowledge of its health consequences is still limited.

OBJECTIVES

We aimed to examine the cognitive effects of mitragynine substitution in morphine-withdrawn rats. Furthermore, we asked whether neuronal addiction markers like the brain-derived neurotrophic factor (BDNF) and Ca²⁺/calmodulin-dependent kinase II alpha (αCaMKII) might mediate the observed effects.

METHODS

Male Sprague-Dawley rats were given morphine at escalating doses before treatment was discontinued to induce a spontaneous morphine withdrawal. Then, vehicle or mitragynine (5 mg/kg, 15 mg/kg, or 30 mg/kg) substitution was given for 3 days. A vehicle-treated group was used as a control. Withdrawal signs were scored after 24 h, 48 h, and 72 h, while novel object recognition (NOR) and attentional set-shifting (ASST) were tested during the substitution period.

RESULTS

Discontinuation of morphine significantly induced morphine withdrawal signs and cognitive deficit in the ASST. The substitution with mitragynine was able to alleviate the withdrawal signs. Mitragynine did not affect the recognition memory in the NOR but significantly improved the reversal learning deficit in the morphine-withdrawn rats.

CONCLUSIONS

These data support the idea that mitragynine could be used as safe medication therapy to treat opiate addiction with beneficial effects on cognitive deficits.

In vitro and in vivo pharmacology of kratom

Kratom products have been historically and anecdotally used in south Asian countries for centuries to manage pain and opioid withdrawal. The use of kratom products has dramatically increased in the United States. More than 45 kratom alkaloids have been isolated, yet the overall pharmacology of the individual alkaloids is still not well characterized. The purpose of this chapter is to summarize in vitro and in vivo opioid activities of the primary kratom alkaloid mitragynine and its more potent metabolite 7-hydroxymitragynine. Following are experimental procedures described to characterize opioid receptor activity; receptor binding and functional assays, antinociceptive assays, operant conditioning assays, and respiratory plethysmography. The capacity of kratom alkaloids to confer tolerance and physical dependence as well as their pharmacokinetic properties are also summarized. The data reviewed here suggest that kratom products and mitragynine possess low efficacy agonist activity at the mu-opioid receptor in vivo. In addition, kratom products and mitragynine have been demonstrated to antagonize the effects of high efficacy mu-opioid agonists. The data further suggest that 7-hydroxymitragynine formed in vivo by metabolism of mitragynine may be minimally involved in the overall behavioral profile of mitragynine and kratom, whereas 7-hydroxymitragynine itself, at sufficiently high doses administered exogenously, shares many of the same abuse- and dependence-related behavioral effects associated with traditional opioid agonists. The apparent low efficacy of kratom products and mitragynine at mu-opioid receptors supports the development of these ligands as effective and potentially safe medications for opioid use disorder.

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.

Multiorgan Dysfunction Related to Kratom Ingestion

Consumption of herbal supplements has been linked to multiorgan toxicities. Kratom is an herbal extract that has gained popularity for its analgesic and psychotropic properties. Several cases of kratom-induced liver injury have been reported, but data on multiorgan involvement remain scarce. We present the case of a 37-year-old woman who developed a mixed hepatocellular and cholestatic pattern of acute liver injury, acute kidney injury, and pancolitis after prolonged use of kratom-containing herbal supplements.

Kratom use disorder: a primer for primary care physicians

Kratom is a substance similar to opioids that is often used for its euphoric effects, however it can be obtained legally in most of the United States. The substance is often not assessed on routine urine drug screen, however it is estimated that millions of people engage in kratom use each year and level of use is rising. Given the increasing prevalence of kratom use, and its potentially lethal consequences, it is imperative that primary care physicians be familiar with this substance and have a framework to approach identification and treatment of individuals with kratom use disorder. This manuscript offers a review of the epidemiology and pharmacology of kratom, along with guidance for care of individuals with kratom use disorder in the primary care setting.

Comprehensive overview of biased pharmacology at the opioid receptors: biased ligands and bias factors

One of the main challenges in contemporary medicinal chemistry is the development of safer analgesics, used in the treatment of pain. Currently, moderate to severe pain is still treated with the "gold standard" opioids whose long-term often leads to severe side effects. With the discovery of biased agonism, the importance of this area of pharmacology has grown exponentially over the past decade. Of these side effects, tolerance, opioid misuse, physical dependence and substance use disorder (SUD) stand out, since these have led to many deaths over the past decades in both USA and Europe. New therapeutic molecules that induce a biased response at the opioid receptors (MOR, DOR, KOR and NOP receptor) are able to circumvent these side effects and, consequently, serve as more advantageous therapies with great promise. The concept of biased signaling extends far beyond the already sizeable field of GPCR pharmacology and covering everything would be vastly outside the scope of this review which consequently covers the biased ligands acting at the opioid family of receptors. The limitation of quantifying bias, however, makes this a controversial subject, where it is dependent on the reference ligand, the equation or the assay used for the quantification. Hence, the major issue in the field of biased ligands remains the translation of the in vitro profiles of biased signaling, with corresponding bias factors to in vivo profiles showing the presence or the lack of specific side effects. This review comprises a comprehensive overview of biased ligands in addition to their bias factors at individual members of the opioid family of receptors, as well as bifunctional ligands.