Herbal InteractionEarly Phase 1NCT05846451
Evaluating a Potential Pharmacokinetic Kratom-oxycodone Interaction Concurrent With Clinical Endpoints
A Early Phase 1 study testing Kratom and Oxycodone in people with Herbal Interaction, run by Washington State University at 1 site in United States.
Trial summary
The goal of this study is to investigate whether the botanical product kratom affects how the body processes the opioid drug oxycodone. The main research questions to be answered are two-fold: 1. How does kratom affect the manner in which oxycodone is metabolized (broken down and removed) by the body? 2. Read more about this study
- Who is it for?
- Ages 21 to 45 yearsHealthy volunteers can take part
- Conditions the study is for
- Herbal Interaction
- What is being tested?
- Kratom and Oxycodone
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 16 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Jun 2023to 1 Dec 2026
- Phase
- Early Phase 1
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 to 45 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Males and females, aged from 21-45 years and healthy
- Body weight between 130 and 250 pounds (60-115 kg) and body mass index between 19 and 30
- Not taking any medications (prescription and non-prescription) or dietary supplements/botanical products known to alter the pharmacokinetics of either oxycodone or kratom
- Willing to abstain from consuming dietary supplements/botanical products and fruit juices for several weeks
- Willing to abstain from cannabis/marijuana, hemp, and THC- and/or CBD-containing products for several weeks
- Willing to abstain from consuming caffeinated beverages or other caffeine-containing products the evening before and morning of any inpatient visit
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- Willing to abstain from consuming alcoholic beverages for one day prior to any inpatient visit
- Willing to use an additional method of contraception that does not include oral contraceptive pills, patches, or other hormonal methods (such as abstinence, copper IUD, or condoms)
- Have consumed kratom previously and tolerated it well without any unpleasant effects
- Willing to abstain from kratom for several weeks
- Have consumed any opioid previously and tolerated it well without any unpleasant effects or addiction
- Written informed consent (and assent when applicable) obtained from subject or subject's legal representative and ability for the subject to comply with the requirements of the study
- Geographically located within a 40-mile radius of Spokane and have the time to participate
Who cannot join
- Males and females under the age of 21 or over the age of 45
- People who weigh less than 130 pounds or more than 250 pounds
- People with a body mass index less than 19 or greater than 30
- Any current major illness or chronic illness including but not limited to kidney disease, hepatic disease, diabetes mellitus, hypertension, coronary artery disease, chronic obstructive pulmonary disease, cancer, or HIV/AIDS
- No previous exposure to kratom
- No previous exposure to an opioid
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- History of anemia or any other significant hematologic disorder
- History of substance abuse, dependence, or addiction or major psychiatric illness
- A need for chronic opioid analgesics
- Use of opioid analgesics 3 weeks prior to initiation of the study
- An imminent likely need for opioid analgesics (e.g., planned dental or surgical procedure)
- Pregnant or nursing
- History of allergy or intolerance to kratom, other opioids, or oxycodone
- Taking concomitant medications, both prescription and non-prescription (including dietary supplements/botanical products), known to alter the pharmacokinetics of kratom or oxycodone
- Presence of a condition or abnormality that, in the opinion of the Investigator, would compromise the safety of the patient or the quality of the data
- History of sleep apnea
- Any prior use of amphetamines, benzodiazepines, cocaine, MDMA, opioids, PCP, or other drugs for recreational purposes
- Use of cannabis/marijuana, hemp, THC-containing products, CBD-containing products, or CBD within the last month
- Out-of-range clinical laboratory value that the study physician considers participation in the study a health risk
- Inability to speak, read, and understand English
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Washington State University College of Pharmacy and Pharmaceutical Sciences
Spokane, Washington, 99202
Mary Paine, PhD, RPh, mary.paine@wsu.edu
About this study
The goal of this study is to investigate whether the botanical product kratom affects how the body processes the opioid drug oxycodone. The main research questions to be answered are two-fold:
- How does kratom affect the manner in which oxycodone is metabolized (broken down and removed) by the body?
- Does kratom change the effects oxycodone exerts on the body?
Healthy adult participants will complete four study arms, during which they will be given the following:
- Kratom (as a tea)
- A single dose of oxycodone (as a tablet)
- Kratom tea and a single dose of oxycodone
- Kratom tea for four days, then kratom tea and a single dose of oxycodone
Read the detailed description
The primary objective of this study is to evaluate the potential for kratom to precipitate a pharmacokinetic interaction with the common opioid and dual cytochrome P450 (CYP) 3A/CYP2D6 substrate oxycodone. A secondary objective is to evaluate a potential pharmacodynamic interaction by measuring pupil diameter, the most sensitive measure of central nervous system opioid effects. To evaluate these objectives, participants will complete four arms, during which they will be administered the following:
- Arm 1: a single low dose of kratom (by mouth, as a tea)
- Arm 2: a single low dose of immediate-release oxycodone (by mouth, as a tablet)
- Arm 3: a single low dose of kratom tea and a single low dose of oxycodone
- Arm 4: daily at-home self-administration of kratom tea for four days, followed immediately by a single low dose of kratom tea and a single low dose of oxycodone in the research setting
- Conditions
- Herbal Interaction
- Being tested
- Kratom, Oxycodone
- Keywords
- pharmacokinetic, pharmacokinetics, pharmacodynamic, pharmacodynamics, kratom, oxycodone, natural product, botanical product, natural product-drug interaction, mitragynine
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
KratomDietary supplement
Kratom (Moon Kratom Yellow Indonesian, lot 51) is supplied as a dry leaf powder in clear plastic bags, each weighing 5 kg. Two grams of kratom dry leaf powder will be stirred into 240 mL of hot water to make a tea. The tea will be cooled to 50 degrees Celsius before administration. Participants will drink the tea within 15 minutes.
OxycodoneDrug
Immediate-release oral tablet, 10 mg
| Study group | Role | What they receive |
|---|---|---|
| Arm 1 | Experimental | Sixteen non-naive* participants (8 males, 8 females) will be administered a single low dose (2 g) of a well-characterized kratom product by mouth as a tea. Pupil diameter will be measured from 0-12 hours. A washout of at least 10 days will separate Arms 1 and 2.
*Non-naive subjects are defined as intermittent users who consume 2-8 g kratom at least once per month but no more than three times daily within the last six months prior to screening and are willing to abstain for several weeks Receives: Dietary Supplement: Kratom |
| Arm 2 | Active comparator | The same 16 participants will be administered a single low dose (10 mg) of immediate-release oxycodone by mouth as a tablet. Plasma, pupil diameter measurements, and urine will be collected from 0-24 hours. A washout of at least 2 days will separate Arms 2 and 3. Receives: Drug: Oxycodone |
| Arm 3 | Experimental | The same 16 participants will be administered a single low dose (2 g) of kratom as a tea. After 15 minutes, the subjects will be administered a single low dose (10 mg) of oxycodone as a tablet by mouth. Plasma, pupil diameter measurements, and urine will be collected from 0-24 hours. A washout of at least 10 days will separate Arms 3 and 4. Receives: Dietary Supplement: Kratom; Drug: Oxycodone |
| Arm 4 | Experimental | The same 16 participants will self-administer a single low dose (2 g) of kratom as a tea once daily at home. On the fifth day, subjects will return to the research setting, where they will be administered a single low dose (2 g) of kratom, followed 15 minutes later by a single low dose (10 mg) of oxycodone by mouth. Plasma, pupil diameter measurements, and urine will be collected from 0-24 hours. Receives: Dietary Supplement: Kratom; Drug: Oxycodone |
What is being measured
The primary outcome is the main question the study is designed to answer.
Oxycodone area under the concentration vs. time curve (AUC) ratio (presence to absence of kratom)
Ratio of the AUC of oxycodone in the presence to absence of kratom.
Measured: 0-24 hours
Secondary outcomes (3)
Area under the pupil diameter (effect) vs. time curve (AUEC) ratio
Ratio of AUEC in presence of oxycodone+kratom to oxycodone
Measured: 0-24 hours
Oxycodone maximum plasma concentration (Cmax) ratio (presence to absence of kratom)
Ratio of Cmax of oxycodone in the presence to absence of kratom.
Measured: 0-24 hours
Oxycodone half-life ratio (presence to absence of kratom)
Ratio of half-life of oxycodone in the presence to absence of kratom
Measured: 0-24 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 May 2023
- Study start1 Jun 2023
- Primary completion1 Nov 2026 (estimated)
- Study completion1 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Herbal InteractionStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Early Phase 1
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 16 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Washington State University
- Sponsor type
- University, hospital or other
- Collaborators
- National Center for Complementary and Integrative Health (NCCIH)
- Responsible party
- Principal investigator, Mary Paine, Washington State University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05846451
- Sponsor's protocol ID
- 19633
- Other IDs
- U54AT008909
- Status last verified
- Jun 2026
- First submitted
- 26 Apr 2023
- Last updated
- 3 Jun 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluating a Potential Pharmacokinetic Kratom-oxycodone Interaction Concurrent With Clinical Endpoints
- ClinicalTrials.gov ID
- NCT05846451
- Acronym / sponsor ID
- 19633
- Conditions
- Herbal Interaction
- Keywords
- pharmacokinetic, pharmacokinetics, pharmacodynamic, pharmacodynamics, kratom, oxycodone, natural product, botanical product
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 16 participants (estimated)
- Lead sponsor
- Washington State UniversityUniversity, hospital or other
- Collaborators
- National Center for Complementary and Integrative Health (NCCIH)
- Study start
- 1 Jun 2023 (actual)
- Primary completion
- 1 Nov 2026 (estimated)
- Study completion
- 1 Dec 2026 (estimated)
- First posted
- 6 May 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this study is to investigate whether the botanical product kratom affects how the body processes the opioid drug oxycodone. The main research questions to be answered are two-fold:
- How does kratom affect the manner in which oxycodone is metabolized (broken down and removed) by the body?
- Does kratom change the effects oxycodone exerts on the body?
Healthy adult participants will complete four study arms, during which they will be given the following:
- Kratom (as a tea)
- A single dose of oxycodone (as a tablet)
- Kratom tea and a single dose of oxycodone
- Kratom tea for four days, then kratom tea and a single dose of oxycodone
Detailed description
The primary objective of this study is to evaluate the potential for kratom to precipitate a pharmacokinetic interaction with the common opioid and dual cytochrome P450 (CYP) 3A/CYP2D6 substrate oxycodone. A secondary objective is to evaluate a potential pharmacodynamic interaction by measuring pupil diameter, the most sensitive measure of central nervous system opioid effects. To evaluate these objectives, participants will complete four arms, during which they will be administered the following:
- Arm 1: a single low dose of kratom (by mouth, as a tea)
- Arm 2: a single low dose of immediate-release oxycodone (by mouth, as a tablet)
- Arm 3: a single low dose of kratom tea and a single low dose of oxycodone
- Arm 4: daily at-home self-administration of kratom tea for four days, followed immediately by a single low dose of kratom tea and a single low dose of oxycodone in the research setting
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Arm 1 | Experimental | Dietary Supplement: KratomSixteen non-naive* participants (8 males, 8 females) will be administered a single low dose (2 g) of a well-characterized kratom product by mouth as a tea. Pupil diameter will be measured from 0-12 hours. A washout of at least 10 days will separate Arms 1 and 2. *Non-naive subjects are defined as intermittent users who consume 2-8 g kratom at least once per month but no more than three times daily within the last six months prior to screening and are willing to abstain for several weeks |
| Arm 2 | Active comparator | Drug: OxycodoneThe same 16 participants will be administered a single low dose (10 mg) of immediate-release oxycodone by mouth as a tablet. Plasma, pupil diameter measurements, and urine will be collected from 0-24 hours. A washout of at least 2 days will separate Arms 2 and 3. |
| Arm 3 | Experimental | Dietary Supplement: Kratom, Drug: OxycodoneThe same 16 participants will be administered a single low dose (2 g) of kratom as a tea. After 15 minutes, the subjects will be administered a single low dose (10 mg) of oxycodone as a tablet by mouth. Plasma, pupil diameter measurements, and urine will be collected from 0-24 hours. A washout of at least 10 days will separate Arms 3 and 4. |
| Arm 4 | Experimental | Dietary Supplement: Kratom, Drug: OxycodoneThe same 16 participants will self-administer a single low dose (2 g) of kratom as a tea once daily at home. On the fifth day, subjects will return to the research setting, where they will be administered a single low dose (2 g) of kratom, followed 15 minutes later by a single low dose (10 mg) of oxycodone by mouth. Plasma, pupil diameter measurements, and urine will be collected from 0-24 hours. |
Who may qualify
- Ages
- 21 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (13 listed)
- Males and females, aged from 21-45 years and healthy
- Body weight between 130 and 250 pounds (60-115 kg) and body mass index between 19 and 30
- Not taking any medications (prescription and non-prescription) or dietary supplements/botanical products known to alter the pharmacokinetics of either oxycodone or kratom
- Willing to abstain from consuming dietary supplements/botanical products and fruit juices for several weeks
- Willing to abstain from cannabis/marijuana, hemp, and THC- and/or CBD-containing products for several weeks
Key exclusion criteria (20 listed)
- Males and females under the age of 21 or over the age of 45
- People who weigh less than 130 pounds or more than 250 pounds
- People with a body mass index less than 19 or greater than 30
- Any current major illness or chronic illness including but not limited to kidney disease, hepatic disease, diabetes mellitus, hypertension, coronary artery disease, chronic obstructive pulmonary disease, cancer, or HIV/AIDS
- No previous exposure to kratom
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| KratomKratom (Moon Kratom Yellow Indonesian, lot 51) is supplied as a dry leaf powder in clear plastic bags, each weighing 5 kg. Two grams of kratom dry leaf powder will be stirred into 240 mL of hot water to make a tea. The tea will be cooled to 50 degrees Celsius before administration. Participants will drink the tea within 15 minutes. | Dietary supplement | Arm 1, Arm 3, Arm 4 |
| OxycodoneImmediate-release oral tablet, 10 mg | Drug | Arm 2, Arm 3, Arm 4 |
Primary outcome
Oxycodone area under the concentration vs. time curve (AUC) ratio (presence to absence of kratom)
Time frame: 0-24 hours
Ratio of the AUC of oxycodone in the presence to absence of kratom.
3 secondary outcomes
Area under the pupil diameter (effect) vs. time curve (AUEC) ratio
Time frame: 0-24 hours
Oxycodone maximum plasma concentration (Cmax) ratio (presence to absence of kratom)
Time frame: 0-24 hours
Oxycodone half-life ratio (presence to absence of kratom)
Time frame: 0-24 hours
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Jun 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing Kratom and Oxycodone in people with Herbal Interaction, run by Washington State University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 13 inclusion and 20 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 3 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Mary Paine, PhD (509-358-7759, mary.paine@wsu.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Oxycodone area under the concentration vs. time curve (AUC) ratio (presence to absence of kratom) (time frame: 0-24 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Jun 2026.