Preliminary Characterization of Commercial Kratom Extract Products

August 11, 2026 updated by: Johns Hopkins University
To understand the acute subjective, physiological, and cognitive effects of commercial kratom extract products among US adults who consume these products regularly, and to understand how these products are metabolized by the human body.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Terminated

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

Kratom products, made from the botanical Mitragyna speciosa, have proliferated in the United States since 2006 and now include a variety of brands and formulations. Kratom whole-leaf products and kratom leaf-derived extract products are the two major types of products within the marketplace. To date, most studies have examined kratom whole-leaf products, both in terms of self-report from consumers and in terms of two US-based, small lab-based pharmacokinetic/pharmacodynamic (PK/PD) studies. In order to follow-up on the investigators' prior work examining the acute effects of kratom in adults (age 21 or older) who regularly use whole-leaf kratom products, the investigators propose a pilot study (N=16) that purposefully samples US adults who use popular kratom extract products sold legally in most of US, including the state of Maryland. Despite the widespread use of kratom extract products, particularly among the best-selling brands, the investigators have no independently collected and published data derived from human laboratory studies on the PK/PD associated with these products. The investigators will conduct a within-person, single-dose pilot study wherein 16 adult consumers of kratom extract products will self-administer a single oral dose of the participant's kratom extract. As this is an exploratory pilot study, the investigators are not making a priori hypothesis. Rather, this is a proof-of-concept pilot study needed to first measure the basic PK and PD (physiological, subjective, cognitive) responses to extract product servings taken by adults who consumed the extracts regularly. There is immediate public health need to better understand kratom extract consumer experiences given that these products are unregulated but widely used. Such data have ecological validity and can inform next steps for funding and research.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Kirsten E Smith, MSW, PhD
  • Phone Number: 865-418-8177
  • Email: ksmit398@jh.edu

Study Contact Backup

  • Name: Carlos Austin Zamarripa, PhD
  • Phone Number: 410-550-6969
  • Email: czamarr2@jhmi.edu

Study Locations

  • United States
    • Maryland
      • Baltimore, Maryland, United States, 21224
        • Johns Hopkins University
      • Baltimore, Maryland, United States, 21224
        • Johns Hopkins University Behavioral Pharmacology Research Unit

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

US adults who use kratom extract products on a regular basis

Description

Inclusion Criteria:

  • 1) >21 years old;
  • 2) Experienced kratom extract product consumer of one of the leading US brands listed in the study protocol;
  • 3) Reports a specific kratom extract product brand and specific dose amount (or range of typical dose amount) on the online screener;
  • 4) English language proficient;
  • 5) Willingness to provide requested samples of the kratom extract product currently being taken.

Exclusion Criteria:

  • 1) Reports any acute adverse or unexpected or otherwise sudden health event related to their typical kratom product dose that occurred within 30 days of screening;
  • 2) Having ever sought medical attention for an acute adverse health event as a result of taking any kratom product;
  • 3) Cannot or will not provide their kratom extract product samples in the form of an unopened package that is clearly labeled with at least the product and vendor name;
  • 4)The kratom extract product used by the participant has any semi-synthetic or fully synthetic ingredient listed or is known by the study team to have such an ingredient;
  • 5) Currently breastfeeding or pregnant;
  • 6) history or current diagnosis of psychotic disorder;
  • 7) current untreated bipolar disorder; 8) current untreated major depressive disorder;
  • 8) Current physical dependence on alcohol, benzodiazepines, or opioids (self-reported or otherwise evidenced) requiring medical intervention;
  • 9) Reports use of fentanyl within the past month and/or has a fentanyl positive drug screen;
  • 10) Discordance between self-reported substance use and drug screen results obtained during screening;
  • 11)Any physical, psychiatric, environmental, situational, or kratom product-related condition considered by the study team to increase risk or undue burden.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
US Adult Kratom Extract Consumers
Participants who regularly consume commercial kratom extracts will orally self-administer a single serving of their commercial kratom extract product under direct observation in order to evaluate acute physiological, subjective, and cognitive effects and determine pharmacokinetics. Participants will undergo direct observation and assessment for acute self-administration and for a period following the peak effects (i.e., a period of short abstinence). Physiological, subjective, and cognitive effects will be measured in an inpatient unit where the participant will reside for 2 days and 1 night (consecutive).

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Drug Effects Questionnaire
Time Frame: Administered at 7 timepoints on Study Days 1-2
Drug Effects Questionnaire (DEQ) visual analogue scale (0-100) rating for DEQ item "feeling" effects and "liking" effects. 0 is the measure of least impactful 'effect'.
Administered at 7 timepoints on Study Days 1-2
Cognitive Effects as assessed by the Digit Symbol Substitution Task
Time Frame: Administered at 7 time points on Study Days 1-2
The 2-minute computerized Digit Symbol Substitution Task (DSST) outcome of total number of correct responses (accuracy) within the 2-minute test window. This will evaluate cognitive performance and impairment.
Administered at 7 time points on Study Days 1-2
Pupil size
Time Frame: Measured at 7 timepoints on Study Days 1-2
Pupil diameter in mm under stable light conditions using a pupilometer.
Measured at 7 timepoints on Study Days 1-2
Resting Heart Rate
Time Frame: Measured at 7 timepoints on Study Days 1-2
Resting heart rate in beats per minute.
Measured at 7 timepoints on Study Days 1-2

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Qualitative Interview
Time Frame: Study Day 2
Qualitative interview of participants' experience with kratom products and how use has changed over time. Will take approximately 1.5 - 2 hours to complete.
Study Day 2

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Johns Hopkins University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
University of Florida

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Kirsten E Smith, MSW, PhD, Johns Hopkins University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 11, 2024

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 23, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 23, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 9, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 10, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 15, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 13, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 11, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IRB00440647

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Data sharing agreements/materials will be implemented to share biospecimen data and limited datasets with deidentified participant information to collaborators for bioanalytics. No protected health information or personally identifiable information will be shared and all data will be coded with unique participant Identification.

IPD Sharing Time Frame

After the study has concluded or upon request.

IPD Sharing Access Criteria

Researchers and scientists university/academic or government settings (non-commercial, non-industry settings) can make a request to the PI.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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