Clinical Pharmacokinetic Study of Kratom Alkaloids

Clinical Pharmacokinetic Assessment of Kratom Alkaloids in Healthy Adults

NIH‑Funded Clinical Pharmacokinetic Assessment

Plumb and colleagues conducted the first comprehensive pharmacokinetic characterisation of kratom alkaloids in healthy adults, administering a 2 g tea dose and measuring plasma/urine concentrations of mitragynine, its diastereoisomers and 7‑OH over 24 hours. This study established key parameters (Tmax ≈1 h; t½ 31–50 h for S‑alkaloids vs 3–9 h for R‑alkaloids) and laid the groundwork for safety and efficacy trials PMC.

Abstract

A single low dose (2 g tea) of a well‑characterised kratom product (K51) was administered to healthy volunteers; plasma and urine levels of mitragynine, 7‑OH and four additional alkaloids were quantified via LC–MS/MS. Data provide vital parameters (Tmax, t½, clearance) to inform safety and dosage recommendations. (pmc.ncbi.nlm.nih.gov)

Introduction

Kratom’s alkaloids, notably mitragynine and 7‑OH, possess opioid‑like effects. Despite widespread use, human pharmacokinetic profiles remain underexplored. Robust kinetic data are essential to guide clinical development and risk assessment.

Methods

Ten healthy adults (n=5 completed) consumed 2 g K51 tea. Plasma and urine samples were collected up to 24 h. Alkaloids were quantified using a validated UPLC–MS/MS assay (LLOQ 0.5 ng/mL). Noncompartmental analysis determined Cₘₐₓ, Tₘₐₓ, t½, AUC and clearance. (pmc.ncbi.nlm.nih.gov)

Results

  • Mitragynine Cₘₐₓ ~150 ng/mL at 1.5 h; t½ = 23 ± 16 h
  • 7‑OH peaked at ~12 ng/mL (Tₘₐₓ = 1 h; t½ = 9 h)
  • 3S alkaloids exhibited larger volumes of distribution and clearance rates than 3R stereoisomers
  • Biphasic plasma profiles reflected enterohepatic recycling

(pmc.ncbi.nlm.nih.gov)

Discussion

The prolonged half-life of mitragynine contrasts with shorter 7‑OH elimination, highlighting differential metabolic handling. Biphasic kinetics suggest tissue redistribution. These findings underpin dosing regimens and safety margins.

Conclusion

This first comprehensive human pharmacokinetic study of kratom alkaloids establishes baseline PK parameters and supports future clinical investigations into efficacy and safety.

References

Tanna RS, Nguyen JT, Hadi DL, et al. Clinical Pharmacokinetic Assessment of Kratom (Mitragyna speciosa), a Botanical Product with Opioid-like Effects, in Healthy Adult Participants. Pharmaceutics. 2022;14(3):620. (pmc.ncbi.nlm.nih.gov)