CYP2C19 Genetic VariantsNCT05078723
CYP2C19 Variants and Limonene Metabolism
A study testing Limonene in people with CYP2C19 Genetic Variants, run by Stanford University at 1 site in United States.
Trial summary
The investigators will examine whether a non-invasive screening tool for CYP2C19 genetic variants can be developed by measuring limonene metabolism. Read more about this study
- Who is it for?
- Ages 18 to 45 yearsHealthy volunteers can take part
- Conditions the study is for
- CYP2C19 Genetic Variants
- What is being tested?
- Limonene
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteUnited States
- Study dates
- 30 Oct 2021to Dec 2026
- Phase
- Interventional
- 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 18 to 45 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age range: Greater than 18 years and less than 45 years.
- Gender: Male or Female
- Ethnicities: East Asian
Who cannot join
- Pregnant and/or Breastfeeding
- previous allergic reaction to limonene, citrus fruits, bovine gelatin, glycerin
- past medical history of cerebrovascular or cardiovascular disease
- veganism
- history of chest pain or shortness of breath in the past month
- certain medications that are CYP2C19 substrates or CYP2C19 inhibitors
- Non-East Asian descent
- age less than 18 y.o or age greater than 45 y.o
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
Stanford School of Medicine
Stanford, California, 94305
Eric Gross, MD/PhD
About this study
Official title: Functional Consequences of CYP2C19 Variants on Limonene Metabolism in Humans
The investigators will examine whether a non-invasive screening tool for CYP2C19 genetic variants can be developed by measuring limonene metabolism.
Read the detailed description
Cytochrome P450 2C19 is an important enzyme that metabolizes many drugs. However, individuals with genetic variants of CYP2C19, such as CYP2C19*2 and CYP2C19*3, are poor metabolizers of these drugs. Therefore, it is of interest to determine whether the investigators can develop a non-invasive assay to identify genetic variants of CYP2C19 by using a substrate for CYP2C19 found in citrus fruit, limonene. The purpose of the study is to examine changes in limonene levels in human breath after drinking orange peel extract for people with CYP2C19*2 and CYP2C19*3 genetic variants versus those that do not.
- Conditions
- CYP2C19 Genetic Variants
- Being tested
- Limonene
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
LimoneneDietary supplement
The investigators will ask the participants to swish 5 times and swallow 1 oz water mixed with 500mg limonene (Jarrow Formula orange peel extract). The participant will be monitored for a total of 2 hours. Breath samples will be acquired at a total of 11 time points throughout the study. Measurements include 2 baseline measurements followed by the orange peel extract consumption.
| Study group | Role | What they receive |
|---|---|---|
| CYP2C19*2 and CYP2C19*3 Variants | Experimental | The group of participants has been genotyped to have the CYP2C19*2 and/or CYP2C19*3 variant during the first part of the study. The participants will consume 1 oz water mixed with 500mg limonene (Jarrow Formula orange peel extract) and be asked to swish 5 times and swallow. All participants will then provide breath samples over the course of 2 hours. The breath sample outcomes will be compared to those of the wild-type CYP2C19 study subjects. Receives: Dietary Supplement: Limonene |
| Wildtype CYP2C19 | Experimental | The group of participants has been genotyped to have wild-type CYP2C19. The participants will consume 1 oz water mixed with 500mg limonene (Jarrow Formula orange peel extract) and be asked to swish 5 times and swallow. All participants will then provide breath samples over the course of 2 hours. The breath sample outcomes will be compared to those of the CYP2C19*2 and/or CYP2C19*3 study subjects. Receives: Dietary Supplement: Limonene |
What is being measured
The primary outcome is the main question the study is designed to answer.
Breath limonene value in parts per billion
The amount of limonene in the breath will be measured by mass spectrometry for each participant.
Measured: 2 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Oct 2021
- Study start30 Oct 2021
- Primary completionMar 2026 (estimated)
- Study completionDec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for CYP2C19 Genetic VariantsStudies of the same condition, open and under way.
- More trials run by Stanford UniversityThe sponsor's other registered studies.
- 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
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Model description
- Human volunteers participating in this study will be given an over the counter orange peel extract and limonene levels will be measured.
- Masking
- None (open label)
- Enrolment
- 20 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Stanford University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Eric Gross, Stanford University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05078723
- Sponsor's protocol ID
- 59978
- Status last verified
- Dec 2024
- First submitted
- 1 Jul 2021
- Last updated
- 16 Dec 2024
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 16 Dec 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Functional Consequences of CYP2C19 Variants on Limonene Metabolism in Humans
- ClinicalTrials.gov ID
- NCT05078723
- Acronym / sponsor ID
- 59978
- Conditions
- CYP2C19 Genetic Variants
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 20 participants (estimated)
- Lead sponsor
- Stanford UniversityUniversity, hospital or other
- Study start
- 30 Oct 2021 (actual)
- Primary completion
- Mar 2026 (estimated)
- Study completion
- Dec 2026 (estimated)
- First posted
- 14 Oct 2021 (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 investigators will examine whether a non-invasive screening tool for CYP2C19 genetic variants can be developed by measuring limonene metabolism.
Detailed description
Cytochrome P450 2C19 is an important enzyme that metabolizes many drugs. However, individuals with genetic variants of CYP2C19, such as CYP2C19*2 and CYP2C19*3, are poor metabolizers of these drugs. Therefore, it is of interest to determine whether the investigators can develop a non-invasive assay to identify genetic variants of CYP2C19 by using a substrate for CYP2C19 found in citrus fruit, limonene. The purpose of the study is to examine changes in limonene levels in human breath after drinking orange peel extract for people with CYP2C19*2 and CYP2C19*3 genetic variants versus those that do not.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Human volunteers participating in this study will be given an over the counter orange peel extract and limonene levels will be measured.
| Arm | Type | Receives |
|---|---|---|
| CYP2C19*2 and CYP2C19*3 Variants | Experimental | Dietary Supplement: LimoneneThe group of participants has been genotyped to have the CYP2C19*2 and/or CYP2C19*3 variant during the first part of the study. The participants will consume 1 oz water mixed with 500mg limonene (Jarrow Formula orange peel extract) and be asked to swish 5 times and swallow. All participants will then provide breath samples over the course of 2 hours. The breath sample outcomes will be compared to those of the wild-type CYP2C19 study subjects. |
| Wildtype CYP2C19 | Experimental | Dietary Supplement: LimoneneThe group of participants has been genotyped to have wild-type CYP2C19. The participants will consume 1 oz water mixed with 500mg limonene (Jarrow Formula orange peel extract) and be asked to swish 5 times and swallow. All participants will then provide breath samples over the course of 2 hours. The breath sample outcomes will be compared to those of the CYP2C19*2 and/or CYP2C19*3 study subjects. |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Age range: Greater than 18 years and less than 45 years.
- Gender: Male or Female
- Ethnicities: East Asian
Key exclusion criteria (8 listed)
- Pregnant and/or Breastfeeding
- previous allergic reaction to limonene, citrus fruits, bovine gelatin, glycerin
- past medical history of cerebrovascular or cardiovascular disease
- veganism
- history of chest pain or shortness of breath in the past month
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 |
|---|---|---|
| LimoneneThe investigators will ask the participants to swish 5 times and swallow 1 oz water mixed with 500mg limonene (Jarrow Formula orange peel extract). The participant will be monitored for a total of 2 hours. Breath samples will be acquired at a total of 11 time points throughout the study. Measurements include 2 baseline measurements followed by the orange peel extract consumption. | Dietary supplement | CYP2C19*2 and CYP2C19*3 Variants, Wildtype CYP2C19 |
Primary outcome
Breath limonene value in parts per billion
Time frame: 2 hours
The amount of limonene in the breath will be measured by mass spectrometry for each participant.
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 16 Dec 2024.
- Individual participant dataSharing planned: No
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 study testing Limonene in people with CYP2C19 Genetic Variants, run by Stanford 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 3 inclusion and 8 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 16 Dec 2024. 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.
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 Eric Gross, MD/PhD ((650)721-4521, ergross@stanford.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Breath limonene value in parts per billion (time frame: 2 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 16 Dec 2024; AzTrials last refreshed its copy on 4 Nov 2026.