What does ADME stand for?

ADME stands for Absorption, Distribution, Metabolism, Excretion, the four processes that pharmacokinetics describes. They cover, respectively: how the compound enters the bloodstream, how it is distributed across tissues, how it is chemically modified (typically in the liver), and how it is eliminated (typically through urine, feces, or breath).

What is the difference between pharmacokinetics and pharmacodynamics?

Pharmacokinetics is what the body does to the compound - exposure over time. Pharmacodynamics is what the compound does to the body - effects at receptors and on physiology. Both are needed for a complete pharmacological characterization.

Cmax is the peak plasma concentration of a compound achieved after dosing. It is measured in concentration units (e.g., ng/mL) and is one of the principal pharmacokinetic exposure metrics.

What is the half-life of 7-OH?

Reported half-life values for 7-hydroxymitragynine come from animal-model pharmacokinetic studies and should be interpreted strictly in research context. Human PK data are limited. See the dedicated Half-Life glossary entry for more detail.

What is bioavailability?

Bioavailability (F) is the fraction of an administered dose that reaches systemic circulation in active form. For oral dosing, F depends on absorption from the gut and on first-pass metabolism in the liver. Compounds heavily metabolized by CYP3A4 typically have lower oral bioavailability than compounds not subject to substantial first-pass metabolism.

Where do PK studies for kratom alkaloids appear?

Published peer-reviewed pharmacokinetic studies are indexed in PubMed and summarized in research-context reviews. The 7-OH Research Library pillar surfaces specific study summaries.

Pharmacology Concepts

Pharmacokinetics

At-a-glance comparison

Spec	Value
Acronym	PK
Defining framework	ADME - Absorption, Distribution, Metabolism, Excretion
Key parameters	Cmax (peak plasma concentration); Tmax (time to peak); AUC (area under curve); t½ (half-life); CL (clearance); Vd (volume of distribution); F (bioavailability)
Distinguished from pharmacodynamics	Pharmacokinetics: what the body does to the compound. Pharmacodynamics: what the compound does to the body.
Standards reference	U.S. FDA Guidance for Industry: Bioanalytical Method Validation; ICH guidelines for clinical PK studies
7-OH PK context	Animal-model studies have characterized PK parameters for both mitragynine and 7-OH; published human PK data are limited

What is pharmacokinetics?

Pharmacokinetics is the quantitative study of how the body handles a compound over time after exposure. It is conventionally summarized by the acronym ADME, standing for Absorption (how the compound enters the bloodstream), Distribution (how it is distributed across tissues), Metabolism (how it is chemically modified, typically in the liver), and Excretion (how it is eliminated, typically through urine, feces, or breath).

Pharmacokinetics is distinguished from pharmacodynamics, which is the study of what the compound does to the body, its effects at receptors, on physiological systems, and on overall function. Pharmacokinetics describes exposure; pharmacodynamics describes response. Both are needed for a complete pharmacological characterization.

Key pharmacokinetic parameters

Several parameters quantify aspects of pharmacokinetics. Cmax is the peak plasma concentration achieved after dosing. Tmax is the time at which Cmax occurs. AUC, the area under the plasma concentration-time curve, integrates total exposure over time. The half-life t½ is the time required for plasma concentration to decrease by half during the elimination phase. Clearance (CL) measures the volume of plasma cleared of the compound per unit time. Volume of distribution (Vd) describes how widely the compound distributes across tissues. Bioavailability (F) measures the fraction of an administered dose that reaches systemic circulation in active form.

These parameters are estimated from concentration-time data in plasma (or other matrices) following compound administration in animal-model or human studies. The estimation typically uses non-compartmental analysis or compartmental modeling depending on the study design.

Pharmacokinetics of kratom alkaloids

Animal-model pharmacokinetic studies have characterized PK parameters for both mitragynine and 7-hydroxymitragynine. These studies describe absorption from oral or other routes, hepatic metabolism (notably the CYP3A4-mediated conversion of mitragynine to 7-OH), distribution across tissues, and elimination. Published human pharmacokinetic data on kratom alkaloids are more limited than animal-model data and are summarized in research-context reviews; results vary with dose form, individual variability, and analytical method.

These pharmacokinetic findings come from research-context studies and are reported in peer-reviewed publications. They describe time-course exposure in research models and should not be interpreted as evidence of safety, efficacy, or any clinical or therapeutic effect in humans.

Common questions about pharmacokinetics

What does ADME stand for?: ADME stands for Absorption, Distribution, Metabolism, Excretion, the four processes that pharmacokinetics describes. They cover, respectively: how the compound enters the bloodstream, how it is distributed across tissues, how it is chemically modified (typically in the liver), and how it is eliminated (typically through urine, feces, or breath).
What is the difference between pharmacokinetics and pharmacodynamics?: Pharmacokinetics is what the body does to the compound - exposure over time. Pharmacodynamics is what the compound does to the body - effects at receptors and on physiology. Both are needed for a complete pharmacological characterization.
What is Cmax?: Cmax is the peak plasma concentration of a compound achieved after dosing. It is measured in concentration units (e.g., ng/mL) and is one of the principal pharmacokinetic exposure metrics.
What is the half-life of 7-OH?: Reported half-life values for 7-hydroxymitragynine come from animal-model pharmacokinetic studies and should be interpreted strictly in research context. Human PK data are limited. See the dedicated Half-Life glossary entry for more detail.
What is bioavailability?: Bioavailability (F) is the fraction of an administered dose that reaches systemic circulation in active form. For oral dosing, F depends on absorption from the gut and on first-pass metabolism in the liver. Compounds heavily metabolized by CYP3A4 typically have lower oral bioavailability than compounds not subject to substantial first-pass metabolism.
Where do PK studies for kratom alkaloids appear?: Published peer-reviewed pharmacokinetic studies are indexed in PubMed and summarized in research-context reviews. The 7-OH Research Library pillar surfaces specific study summaries.

References

U.S. Food and Drug Administration. (2018). Bioanalytical Method Validation: Guidance for Industry.
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.
Rowland M, Tozer TN. (2010). Clinical Pharmacokinetics and Pharmacodynamics: Concepts and Applications (4th ed.).

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.