How is half-life calculated?

From the rate of decline of plasma concentration during the terminal elimination phase, derived from the relationship t½ = (0.693 × Vd) / CL where Vd is volume of distribution and CL is clearance. The natural log of 2 (≈0.693) appears because half-life describes a 50% decrease in concentration.

What is the half-life of 7-OH?

Reported half-life values for 7-hydroxymitragynine come from animal-model pharmacokinetic studies and a smaller number of human studies. Specific values vary across publications and depend on study design, dose form, and analytical method. Half-life is a research-context PK parameter, not consumer-use guidance.

How long does it take to reach steady state on regular dosing?

Approximately four to five half-lives. This applies in research-pharmacokinetic terms; it is not dosing guidance for any consumer product.

Why is human half-life data for 7-OH limited?

Limited human PK data on 7-OH reflects the regulatory status of the compound (no FDA approval; FDA recommended Schedule I status in July 2025) and the resulting limits on clinical research. Animal-model PK studies are more extensive.

Pharmacology Concepts

Half-Life

At-a-glance comparison

Spec	Value
Symbol	t½ (often written as t1/2 or t-half)
Defining equation	t½ = (0.693 × Vd) / CL - half-life equals the natural log of 2 times volume of distribution divided by clearance
What it describes	Time for plasma concentration to fall by 50% during elimination
Number of half-lives to ~steady state on regular dosing	Approximately 4-5
Where it appears in pharmacokinetic data	Reported alongside Cmax, Tmax, AUC, and clearance
7-OH animal-model context	Reported half-life values vary with species, route of administration, and dose form; reference the dedicated study summaries on 7oh.com for specific values
Important caveat	Half-life is a research-context PK parameter, not consumer-use guidance

What is half-life?

In pharmacokinetics, half-life - denoted t½ - is the time required for the plasma concentration of a compound to decrease by half during the elimination phase, after absorption and distribution have completed. The half-life is a derived parameter, calculated from two more fundamental parameters: clearance (CL, the volume of plasma cleared of the compound per unit time) and volume of distribution (Vd, the apparent volume across which the compound is distributed). The relationship is t½ = (0.693 × Vd) / CL, where 0.693 is the natural logarithm of 2.

Half-life describes elimination kinetics. After approximately four to five half-lives of regular dosing at a constant interval, plasma concentration reaches steady state - meaning the amount eliminated per dosing interval equals the amount administered. After dosing stops, approximately four to five half-lives are required for plasma concentration to fall to negligible levels.

How is half-life determined?

Half-life is estimated from concentration-time data in plasma (or other matrices) following compound administration. Plasma samples are drawn at multiple time points after dosing, and the concentration of the parent compound (and often metabolites) is measured by a validated analytical method - typically LC-MS or LC-MS/MS for kratom alkaloid studies. The terminal elimination phase of the concentration-time curve is identified, and half-life is calculated from the rate of decline in that phase.

Several factors influence reported half-life values: the analytical method's sensitivity, the duration of post-dose sampling, individual variability, dose form (single-dose vs steady-state), and species (animal model vs human). Published half-life values for the same compound can therefore differ across studies, and any specific value should be interpreted in the context of the study design that produced it.

Half-life of 7-hydroxymitragynine and mitragynine in research models

Reported half-life values for mitragynine and 7-hydroxymitragynine come predominantly from animal-model pharmacokinetic studies (for example, in rats and dogs) and from a smaller number of human pharmacokinetic studies. Specific reported values vary across publications and depend on the study design, dose form, and analytical method. The dedicated study summaries in the 7-OH Research Library pillar surface specific values from individual published studies; we do not repeat numerical values here in glossary form because such values are sensitive to interpretation and we want to direct readers to the original research.

Importantly, half-life is a pharmacokinetic research parameter, not consumer-use guidance. This page does not provide dosing instructions or recommendations for any product. Verify any specific half-life value in the cited primary research before relying on it.

Common questions about half-life

What does t½ mean?: t½ is the symbol for half-life - the time required for plasma concentration of a compound to decrease by half during the elimination phase. It is one of the principal pharmacokinetic parameters.
How is half-life calculated?: From the rate of decline of plasma concentration during the terminal elimination phase, derived from the relationship t½ = (0.693 × Vd) / CL where Vd is volume of distribution and CL is clearance. The natural log of 2 (≈0.693) appears because half-life describes a 50% decrease in concentration.
What is the half-life of 7-OH?: Reported half-life values for 7-hydroxymitragynine come from animal-model pharmacokinetic studies and a smaller number of human studies. Specific values vary across publications and depend on study design, dose form, and analytical method. Half-life is a research-context PK parameter, not consumer-use guidance.
How long does it take to reach steady state on regular dosing?: Approximately four to five half-lives. This applies in research-pharmacokinetic terms; it is not dosing guidance for any consumer product.
Why is human half-life data for 7-OH limited?: Limited human PK data on 7-OH reflects the regulatory status of the compound (no FDA approval; FDA recommended Schedule I status in July 2025) and the resulting limits on clinical research. Animal-model PK studies are more extensive.

References

Rowland M, Tozer TN. (2010). Clinical Pharmacokinetics and Pharmacodynamics: Concepts and Applications (4th ed.).
Kamble SH, Sharma A, King TI, et al. (2020). Exploration of cytochrome P450 inhibition mediated drug-drug interaction potential of kratom alkaloids. Toxicology Letters.
Trakulsrichai S, Sathirakul K, Auparakkitanon S, et al. (2015). Pharmacokinetics of mitragynine in man. Drug Design, Development and Therapy.
Wilson LL, Harris HM, Eans SO, et al. (2020). Lyophilized kratom tea as a therapeutic option for opioid dependence. Drug and Alcohol Dependence.

Important safety information:

Products containing 7-hydroxymitragynine (7-OH) are sold for adult use only (21+). These statements have not been evaluated by the U.S. Food and Drug Administration. Products are not intended to diagnose, treat, cure, or prevent any disease. The FDA has raised safety concerns regarding concentrated 7-OH products; consult a qualified healthcare professional before use. Do not operate vehicles or machinery after use. Keep out of reach of children and pets. Laws vary by state, buyers are responsible for knowing applicable law.

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