FDA-Sponsored Phase 1 Clinical Trial: Single Ascending Doses of Kratom Show Safety Profile in Healthy Volunteers

Why it matters

This completed Phase 1 clinical trial represents the first FDA-approved human pharmacokinetics and pharmacodynamics study of kratom across ascending doses (1–12g) in adult recreational polydrug users with opioid experience. Results provide baseline safety data on mitragynine absorption and peak effects.

The big picture

Altasciences conducted a randomized, double-blind, placebo-controlled study enrolling 40 healthy, nondependent adult recreational polydrug users with opioid experience. Five cohorts received single doses of kratom ranging from 1g to 12g, with measurements of pharmacokinetics (what the body does to the drug) and pharmacodynamics (what the drug does to the body). The study was completed in January 2024, with full results posted in September 2025.

Key findings

• 40 subjects enrolled across 5 cohorts (6 active, 2 placebo per cohort)
• Doses tested: 1g, 3g, 8g, 10g, and 12g of kratom
• Study measured pharmacokinetics of mitragynine, 7-hydroxymitragynine, and related alkaloids
• Secondary outcomes tracked drug liking, high ratings, and willingness to take again
• Results examined liver function, kidney function, cardiovascular effects, and respiratory measures

What they say

The study protocol states: "This is a phase I, single-dose, randomized, adaptive, double-blind, placebo-controlled, single ascending dose (SAD), sequential group study... to learn about safety, pharmacokinetics and pharmacodynamics of Kratom in adult recreational polydrug users with opioid experience." Results were posted on ClinicalTrials.gov in September 2025.

Bottom line

**FDA-regulated Phase 1 clinical trial of kratom at multiple doses completed with safety and pharmacokinetic data now available; implications for understanding dose-response effects and alkaloid absorption pending peer-reviewed publication.**