Preliminary Characterization of Commercial Kratom Extract Products

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: Recruiting
• Conditions: Kratom Pharmacokinetics; Kratom Pharmacodynamics

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: Observational
• Enrollment (Estimated): 16

Contacts and Locations

• Study Contact: 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
      • Recruiting
      • Johns Hopkins University
    • Baltimore, Maryland, United States, 21224
      • Not yet recruiting
      • Johns Hopkins University Behavioral Pharmacology Research Unit
      • Contact: Kirsten E Smith, MSW, PhD; Phone Number: 865-418-8177; Email: ksmit398@jh.edu
      • Principal Investigator: Kirsten E Smith, MSW, PhD

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

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

Outcome Measure	Measure Description	Time Frame
Drug Effects Questionnaire	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	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	Pupil diameter in mm under stable light conditions using a pupilometer.	Measured at 7 timepoints on Study Days 1-2
Resting Heart Rate	Resting heart rate in beats per minute.	Measured at 7 timepoints on Study Days 1-2

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Qualitative Interview	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

• Sponsor: Johns Hopkins University
• Collaborators: University of Florida
• Investigators: Principal Investigator: Kirsten E Smith, MSW, PhD, Johns Hopkins University

Study record dates

Study Major Dates

• Study Start (Actual): November 11, 2024
• Primary Completion (Estimated): November 11, 2027
• Study Completion (Estimated): November 1, 2028

Study Registration Dates

• First Submitted: October 9, 2024
• First Submitted That Met QC Criteria: October 10, 2024
• First Posted (Actual): October 15, 2024

Study Record Updates

• Last Update Posted (Actual): November 17, 2025
• Last Update Submitted That Met QC Criteria: November 13, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: pharmacokinetics; behavioral pharmacology; kratom; kratom extracts; Mitragyna speciosa
• Other Study ID 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