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Huestis MA, Brett MA, Bothmer J, Atallah R. Human Mitragynine and 7-Hydroxymitragynine Pharmacokinetics after Single and Multiple Daily Doses of Oral Encapsulated Dried Kratom Leaf Powder. Molecules 2024; 29:984. [PMID: 38474495 DOI: 10.3390/molecules29050984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 01/21/2024] [Accepted: 01/26/2024] [Indexed: 03/14/2024] Open
Abstract
Kratom leaves, consumed by millions worldwide as tea or ground leaf powder, contain multiple alkaloids, with mitragynine being the most abundant and responsible for most effects. Mitragynine is a partial µ-opioid receptor agonist and competitive antagonist at κ- and δ-opioid receptors; however, unlike morphine, it does not activate the β-arrestin-2 respiratory depression pathway. Due to few human mitragynine data, the largest randomized, between-subject, double-blind, placebo-controlled, dose-escalation study of 500-4000 mg dried kratom leaf powder (6.65-53.2 mg mitragynine) was conducted. LC-MS/MS mitragynine and 7-hydroxymitragynine plasma concentrations were obtained after single and 15 daily doses. Mitragynine and 7-hydroxymitragynine Cmax increased dose proportionally, and AUC was slightly more than dose proportional. The median mitragynine Tmax was 1.0-1.3 h after single and 1.0-1.7 h after multiple doses; for 7-hydroxymitragynine Tmax, it was 1.2-1.8 h and 1.3-2.0 h. Steady-state mitragynine concentrations were reached in 8-9 days and 7-hydroxymitragynine within 7 days. The highest mean mitragynine T1/2 was 43.4 h after one and 67.9 h after multiple doses, and, for 7-hydroxymitragynine, it was 4.7 and 24.7 h. The mean 7-hydroxy-mitragynine/mitragynine concentration ratios were 0.20-0.31 after a single dose and decreased (0.15-0.21) after multiple doses. These mitragynine and 7-hydroxymitragynine data provide guidance for future clinical kratom dosing studies and an interpretation of clinical and forensic mitragynine and 7-hydroxymitragynine concentrations.
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Affiliation(s)
- Marilyn A Huestis
- Institute of Emerging Health Professions, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | | | - John Bothmer
- JB Pharma Consulting, 6418PR Heerlen, The Netherlands
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McCurdy CR, Sharma A, Smith KE, Veltri CA, Weiss ST, White CM, Grundmann O. An update on the clinical pharmacology of kratom: uses, abuse potential, and future considerations. Expert Rev Clin Pharmacol 2024; 17:131-142. [PMID: 38217374 PMCID: PMC10846393 DOI: 10.1080/17512433.2024.2305798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 01/11/2024] [Indexed: 01/15/2024]
Abstract
INTRODUCTION Kratom (Mitragyna speciosa) has generated substantial clinical and scientific interest as a complex natural product. Its predominant alkaloid mitragynine and several stereoisomers have been studied for activity in opioid, adrenergic, and serotonin receptors. While awaiting clinical trial results, the pre-clinical evidence suggests a range of potential therapeutic applications for kratom with careful consideration of potential adverse effects. AREAS COVERED The focus of this review is on the pharmacology, pharmacokinetics, and potential drug-drug interactions of kratom and its individual alkaloids. A discussion on the clinical pharmacology and toxicology of kratom is followed by a summary of user surveys and the evolving concepts of tolerance, dependence, and withdrawal associated with kratom use disorder. EXPERT OPINION With the increasing use of kratom in clinical practice, clinicians should be aware of the potential benefits and adverse effects associated with kratom. While many patients may benefit from kratom use with few or no reported adverse effects, escalating dose and increased use frequency raise the risk for toxic events in the setting of polysubstance use or development of a use disorder.
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Affiliation(s)
- Christopher R McCurdy
- College of Pharmacy, Department of Pharmaceutics, University of Florida, FL, 32610, U.S.A
- College of Pharmacy, Department of Medicinal Chemistry, University of Florida, FL, 32610, U.S.A
| | - Abhisheak Sharma
- College of Pharmacy, Department of Pharmaceutics, University of Florida, FL, 32610, U.S.A
| | - Kirsten E. Smith
- School of Medicine, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, MD, 21205, U.S.A
| | - Charles A. Veltri
- Midwestern University, College of Pharmacy, Department of Pharmaceutical Sciences, Glendale, AZ, 85308, U.S.A
| | - Stephanie T. Weiss
- Translational Addiction Medicine Branch, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, U.S.A
| | - Charles M. White
- University of Connecticut School of Pharmacy, Storrs, CT, and Department of Pharmacy, Hartford Hospital, Hartford, CT, U.S.A
| | - Oliver Grundmann
- College of Pharmacy, Department of Medicinal Chemistry, University of Florida, FL, 32610, U.S.A
- Midwestern University, College of Pharmacy, Department of Pharmaceutical Sciences, Glendale, AZ, 85308, U.S.A
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