K. Vicknasingam1, W-T. Chooi2, A.A. Rahim1, D. Ramachandran1, S. Ramanathan1, D. Singh1, H. Zainal3, M.C. Chawarski4. 1Centre for Drug Research, Universiti Sains Malaysia, Malaysia; 2School of Social Sciences, Universiti Sains Malaysia, Malaysia; 3School of Pharmaceutical Sciences, Universiti Sains Malaysia, Malaysia; 4Yale School of Medicine, United States
Background: Kratom tree has a long history of folk medicine use in Malaysia and the neighboring countries. Pain relieve is among many purported beneficial kratom effects. However, kratom effects have never been evaluated in rigorously controlled research. Methods: A double blind, placebo-controlled study, enrolling individuals regularly consuming kratom decoction was conducted to evaluate changes in pain tolerance using a cold pressor task. Participants stayed in an inpatient hospital ward for approximately 20 hours. They consumed a randomized sequence of kratom and placebo drinks, matched for taste and appearance, and completed a series of pain assessment tasks in addition to evaluations of their health status. Results: A total of 26 Malaysian male participants were enrolled. Their mean age was 24.3 (3.4) years and they reported the mean of 6.1 (3.2) years of daily kratom consumption. No discomforts, unusual symptoms, or signs of withdrawal symptoms were reported or observed during the study. Pain tolerance increased at one hour after ingestion of the active kratom drink from the mean of 11.2 (6.7) seconds immediately before consuming kratom to 24.9 (39.4) seconds at one hour after kratom consumption. In contrast, the mean duration of pain tolerance was unchanged: 10.3 (6.0) seconds immediately before, and 11.2 (6.7) seconds at one hour after consuming the placebo drink. Conclusion: Kratom decoction demonstrated potential pain-relieving properties in this first human laboratory placebo-controlled study. Small sample size and large data variability limit generalizability of the findings. Further extensive and rigorous research on kratom safety and pain efficacy is needed.