Kratom Use Within the Context of the Evolving Opioid Crisis and the COVID-19 Pandemic in the United States

Discovery of procyanidin condensed tannins of (-)-epicatechin from Kratom, Mitragyna speciosa, as virucidal agents against SARS-CoV-2

Kratom, Mitragyna speciosa, is one of the most popular herbs in the West and Southeast Asia. A number of previous works have focused on bioactive alkaloids in this plant; however, non-alkaloids have never been investigated for their biological activities. Antiviral and virucidal assays of a methanol leaf extract of Kratom, M. speciosa, revealed that a crude extract displayed virucidal activity against the SARS-CoV-2. Activity-guided isolation of a methanol leaf extract of Kratom led to the identification of B-type procyanidin condensed tannins of (-)-epicatechin as virucidal compounds against SARS-CoV-2. The fraction containing condensed tannins exhibited virucidal activity with an EC50 value of 8.38 μg/mL and a selectivity index (SI) value >23.86. LC-MS/MS analysis and MALDI-TOF MS identified the structure of the virucidal compounds in Kratom as B-type procyanidin condensed tannins, while gel permeation chromatograph (GPC) revealed weight average molecular weight of 238,946 Da for high molecular-weight condensed tannins. In addition to alkaloids, (-)-epicatechin was found as a major component in the leaves of M. speciosa, but it did not have virucidal activity. Macromolecules of (-)-epicatechin, i.e., procyanidin condensed tannins, showed potent virucidal activity against SARS-CoV-2, suggesting that the high molecular weights of these polyphenols are important for virucidal activity.

Kratom safety and toxicology in the public health context: research needs to better inform regulation

Although kratom use has been part of life for centuries in Southeast Asia, the availability and use of kratom in the United States (US) increased substantially since the early 2000s when there was little information on kratom pharmacology, use patterns, and effects, all critical to guiding regulation and policy. Here we provide a synthesis of research with several hundred English-language papers published in the past 5 years drawing from basic research, epidemiological and surveillance data, and recent clinical research. This review of available literature aims to provide an integrated update regarding our current understanding of kratom's benefits, risks, pharmacology, and epidemiology, which may inform United States-based kratom regulation. Recent surveillance indicates there are likely several million past-year kratom consumers, though estimates vary widely. Even without precise prevalence data, kratom use is no longer a niche, with millions of United States adults using it for myriad reasons. Despite its botanical origins in the coffee tree family and its polypharmacy, kratom is popularly characterized as an opioid with presumed opioid-system-based risks for addiction or overdose. Neuropharmacology, toxicology, and epidemiology studies show that kratom is more accurately characterized as a substance with diverse and complex pharmacology. Taken together the work reviewed here provides a foundation for future scientific studies, as well as a guide for ongoing efforts to regulate kratom. This work also informs much-needed federal oversight, including by the United States Food and Drug Administration. We conclude with recommendations for kratom regulation and research priorities needed to address current policy and knowledge gaps around this increasingly used botanical product.

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.

Kratom availability in California vape shops

Kratom products are derived from trees native to Southeast Asia and have dose-dependent stimulant and opioid-like effects. Despite being on the Drug Enforcement Administration "Drugs and Chemicals of Concern List," kratom is legal for sale in most US states. However, there are scarce data on its availability. The goal of this study was to examine kratom availability in vape shops across the state of California and assess shop compliance with a local kratom sales ban (enacted in 2016) in San Diego City. As part of a larger study about retail tobacco marketing near colleges, availability of kratom was assessed in summer 2019 in a random sample of 614 vape shops that was stratified to compare stores near (≤ 3 miles) and distant (>3 miles) from colleges. Logistic regression examined kratom availability as a function of store type (stores that sold vape products only vs. stores selling other tobacco), nearness to college, and tract-level demographics. Kratom was available in 62.4% of observed stores and more often in vape-and-smoke (81.1%) than vape-only shops (11.5%, AOR = 40.4, 95% CI = 23.3-74.1). Kratom availability did not differ by nearness to colleges. In San Diego City, 46.2% of observed stores (95% CI = 28.8-64.5) sold kratom products. Findings indicate that kratom was available in the majority of vape shops and most commonly in vape-and-smoke shops. Widespread availability in tobacco specialty shops suggests the need for research on dual use with tobacco, kratom advertising and cross-product promotion, and the potential of state and local tobacco retail licensing to prohibit sales.

Cannabinoid mechanisms contribute to the therapeutic efficacy of the kratom alkaloid mitragynine against neuropathic, but not inflammatory pain

AIMS

Mitragynine (MG) is an alkaloid found in Mitragyna speciosa (kratom), a plant used to self-treat symptoms of opioid withdrawal and pain. Kratom products are commonly used in combination with cannabis, with the self-treatment of pain being a primary motivator of use. Both cannabinoids and kratom alkaloids have been characterized to alleviate symptoms in preclinical models of neuropathic pain such as chemotherapy-induced peripheral neuropathy (CIPN). However, the potential involvement of cannabinoid mechanisms in MG's efficacy in a rodent model of CIPN have yet to be explored.

MAIN METHODS

Prevention of oxaliplatin-induced mechanical hypersensitivity and formalin-induced nociception were assessed following intraperitoneal administration of MG and CB1, CB2, or TRPV1 antagonists in wildtype and cannabinoid receptor knockout mice. The effects of oxaliplatin and MG exposure on the spinal cord endocannabinoid lipidome was assessed by HPLC-MS/MS.

KEY FINDINGS

The efficacy of MG on oxaliplatin-induced mechanical hypersensitivity was partially attenuated upon genetic deletion of cannabinoid receptors, and completely blocked upon pharmacological inhibition of CB1, CB2, and TRPV1 channels. This cannabinoid involvement was found to be selective to a model of neuropathic pain, with minimal effects on MG-induced antinociception in a model of formalin-induced pain. Oxaliplatin was found to selectively disrupt the endocannabinoid lipidome in the spinal cord, which was prevented by repeated MG exposure.

SIGNIFICANCE

Our findings suggest that cannabinoid mechanisms contribute to the therapeutic efficacy of the kratom alkaloid MG in a model of CIPN, which may result in increased therapeutic efficacy when co-administered with cannabinoids.

Kratom Alkaloids, Cannabinoids, and Chronic Pain: Basis of Potential Utility and Role in Therapy

Introduction: Chronic neuropathic pain is as a severe detriment to overall quality of life for millions of Americans. Current pharmacological treatment options for chronic neuropathic pain are generally limited in efficacy and may pose serious adverse effects such as risk of abuse, nausea, dizziness, and cardiovascular events. Therefore, many individuals have resorted to methods of pharmacological self-treatment. This narrative review summarizes the existing literature on the utilization of two novel approaches for the treatment of chronic pain, cannabinoid constituents of Cannabis sativa and alkaloid constituents of Mitragyna speciosa (kratom), and speculates on the potential therapeutic benefits of co-administration of these two classes of compounds. Methods: We conducted a narrative review summarizing the primary motivations for use of both kratom and cannabis products based on epidemiological data and summarize the pre-clinical evidence supporting the application of both kratom alkaloids and cannabinoids for the treatment of chronic pain. Data collection was performed using the PubMed electronic database. The following word combinations were used: kratom and cannabis, kratom and pain, cannabis and pain, kratom and chronic pain, and cannabis and chronic pain. Results: Epidemiological evidence reports that the self-treatment of pain is a primary motivator for use of both kratom and cannabinoid products among adult Americans. Further evidence shows that use of cannabinoid products may precede kratom use, and that a subset of individuals concurrently uses both kratom and cannabinoid products. Despite its growing popularity as a form of self-treatment of pain, there remains an immense gap in knowledge of the therapeutic efficacy of kratom alkaloids for chronic pain in comparison to that of cannabis-based products, with only three pre-clinical studies having been conducted to date. Conclusion: There is sufficient epidemiological evidence to suggest that both kratom and cannabis products are used to self-treat pain, and that some individuals actively use both drugs, which may produce potential additive or synergistic therapeutic benefits that have not yet been characterized. Given the lack of pre-clinical investigation into the potential therapeutic benefits of kratom alkaloids against forms of chronic pain, further research is warranted to better understand its application as a treatment alternative.

Endogenous opiates and behavior: 2021

This paper is the forty-fourth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2021 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonizts and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Drug testing for mitragynine and kratom: Analytical challenges and medico-legal considerations

Mitragyna speciosa, known as kratom, is a tropical tree native to Southeast Asia that has long been used to increase energy and in traditional medicine. Kratom leaves contain several indole alkaloids including mitragynine, mitraciliatine, speciogynine, and speciociliatine, which have the same molecular formula and connectivity, but different spatial arrangements (i.e., diastereomers). A routine liquid-chromatographic-high-resolution mass-spectrometric (LC-HRMS) multi-analyte method for addictive and herbal drugs in urine did not separate mitragynine from speciogynine and speciociliatine. Separation and individual measurement of the four diastereomers was possible with an improved LC method. All diastereomers were detected in 29 patient urine samples who tested positive for mitragynine with the routine method, albeit at variable absolute amounts and relative proportions. The presence of all diastereomers rather than individual substances indicated that they originated from the intake of kratom (i.e., plant material). Speciociliatine dominated in most samples (66%), whereas mitragynine and mitraciliatine were the highest in 17% each. A kratom product (powdered plant material) marketed in Sweden contained all diastereomers with mitragynine showing the highest level. In Sweden, there are signs of an increasing use of kratom in society, based on the results from drug testing, the number of poisons center consultations on intoxications, and customs seizure statistics. Because there may be health risks associated with kratom use, including dependence, serious adverse reactions, and death, analytical methods should be able to identify and quantify all diastereomers. In Sweden, this is important from a legal perspective, as only mitragynine is classified, whereas the other three diastereomers, and kratom (plant material), are not.

Kratom use categories and their associations with co-occurring substance use and mental health disorder symptoms during the COVID-19 pandemic

BACKGROUND

Kratom, a psychoactive substance, use is an evolving research area that needs more studies to augment the limited literature. Our study examines the association between kratom use categories and mental health and substance use disorders in the U.S.

METHODS

We used the 2020 National Survey on Drug Use and Health data (N = 32,893), a cross-sectional survey data, on the U.S. population aged 12 years or older. We used STATA/SE version 16 to perform a multinomial logistic regression analysis to assess our study aims.

RESULTS

Bisexuals, compared to heterosexuals, had higher risks of kratom use within the past 30 days (relative risk ratio [RRR]= 2.47, 95% CI= 1.07, 5.71). Major depressive episode was positively associated with kratom use more than 30 days ago (RRR= 2.04, 95% CI= 1.24, 3.34). This association was also observed for mild (RRR= 2.04, 95% CI= 1.38, 3.02), moderate (RRR= 2.25, 95% CI= 1.13, 4.51), or severe alcohol use disorder (RRR= 1.88, 95% CI= 1.05, 3.36); and mild (RRR= 1.98, 95% CI= 1.27, 3.11), moderate (RRR= 2.38, 95% CI= 1.27, 4.45), or severe marijuana use disorder (RRR= 2.13, 95% CI= 1.02, 4.47). Illicit drug other than marijuana use disorder was associated positively with kratom use more than 30 days ago (RRR= 2.81, 95% CI= 1.85, 4.26) and kratom use within the past 30 days (RRR= 5.48, 95% CI= 1.50, 20.02).

CONCLUSIONS

Our findings suggested that identifying as bisexual, experiencing depression, alcohol use disorder, or illicit drug use disorder increased the risks of kratom use. There is a need to consider mental health and substance use disorders and sexual identity in kratom use interventions and policies geared toward reducing or preventing kratom use.

Kratom: History, pharmacology, current user trends, adverse health effects and potential benefits

Kratom (Mitragyna speciosa Korth.) is a tree native to Southeast Asia with dose-dependent stimulant and opioid-like effects. Dried, powdered leaf material is among the kratom products most commonly consumed in the US and Europe, but other formulations also exist including enriched extracts, resins, tinctures, and edibles. Its prevalence in the US remains debated and the use pattern includes self-treatment of mood disorders, pain, and substance use disorders. Most of the adverse effects of kratom and its alkaloid mitragynine have been reported in the literature as case reports or part of surveys necessitating confirmation by clinical trials. Toxicities associated with kratom consumption have focused on hepatic, cardiac, and CNS effects with the potential to cause fatalities primarily as part of polydrug exposures. Kratom may also present with drug-drug interactions primarily through CYP 3A4 and 2D6 inhibition, although the clinical significance remains unknown to date. The variability in composition of commercially available kratom products complicates generalization of findings and requires further investigation by employing clinical trials. Healthcare professionals should remain cautious in counseling patients on the use of kratom in a therapeutic setting.

Health Effects Associated With Kratom (Mitragyna speciosa) and Polysubstance Use: A Narrative Review

Background

Kratom (Mitragyna speciosa) consumption and associated health effects have raised debates in the United States. Although most people using this herb do not experience adverse health effects associated with kratom use, medical providers should be knowledgeable of emerging substances and concurrent, sequential, or simultaneous use of other drugs which may impact healthcare recommendations and prescribing practices.

Methods

The objective of this narrative review was to elucidate selected health effects associated with using kratom-either alone or with other substances. Since scientifically controlled human subjects research on kratom use is still limited, relevant case reports were also described.

Results

Cardiovascular, gastrointestinal, neurological, and psychiatric effects associated with kratom use were especially notable, and in-utero exposure accompanied concern regarding a neonate's risk for developing neonatal abstinence syndrome. Our ability to identify and understand the role of this herb in kratom-associated fatalities is complicated since kratom is not routinely screened for in standard forensic toxicology. If a screening is performed, it is usually for the major alkaloid, mitragynine, as a surrogate for kratom use. In addition to lacking a standard practice of screening decedents for kratom alkaloids, the association between mortality and kratom use may be confounded by polysubstance use, adulteration of kratom products, and drug-herb interactions.

Conclusions

Increasing medical awareness of this herb is vital to ensuring prompt administration of best-practice medical advice or treatment for people seeking information related to kratom use or for patients experiencing an adverse health effect that may be associated with using or withdrawing from kratom. Knowledge gained from continued surveillance and study of kratom and its associated health effects may assist in guiding clinical decision-making and preventing development of adverse health effects among people using kratom.

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.

Respiratory effects of oral mitragynine and oxycodone in a rodent model

RATIONALE

Kratom derives from Mitragyna speciosa (Korth.), a tropical tree in the genus Mitragyna (Rubiaceae) that also includes the coffee tree. Kratom leaf powders, tea-like decoctions, and commercial extracts are taken orally, primarily for health and well-being by millions of people globally. Others take kratom to eliminate opioid use for analgesia and manage opioid withdrawal and use disorder. There is debate over the possible respiratory depressant overdose risk of the primary active alkaloid, mitragynine, a partial μ-opioid receptor agonist, that does not signal through ß-arrestin, the primary opioid respiratory depressant pathway.

OBJECTIVES

Compare the respiratory effects of oral mitragynine to oral oxycodone in rats with the study design previously published by US Food and Drug Administration (FDA) scientists for evaluating the respiratory effects of opioids (Xu et al., Toxicol Rep 7:188-197, 2020).

METHODS

Blood gases, observable signs, and mitragynine pharmacokinetics were assessed for 12 h after 20, 40, 80, 240, and 400 mg/kg oral mitragynine isolate and 6.75, 60, and 150 mg/kg oral oxycodone hydrochloride.

FINDINGS

Oxycodone administration produced significant dose-related respiratory depressant effects and pronounced sedation with one death each at 60 and 150 mg/kg. Mitragynine did not yield significant dose-related respiratory depressant or life-threatening effects. Sedative-like effects, milder than produced by oxycodone, were evident at the highest mitragynine dose. Maximum oxycodone and mitragynine plasma concentrations were dose related.

CONCLUSIONS

Consistent with mitragynine's pharmacology that includes partial µ-opioid receptor agonism with little recruitment of the respiratory depressant activating β-arrestin pathway, mitragynine produced no evidence of respiratory depression at doses many times higher than known to be taken by humans.