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.

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.

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.

US adults who use kratom extract products on a regular basis

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.

After the study has concluded or upon request.

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