Examining how limonene metabolism relates to CYP2C19 genetic variants

Functional Consequences of CYP2C19 Variants on Limonene Metabolism in Humans

NA · Stanford University · NCT05078723

This study is testing if measuring how limonene from orange peel extract is processed in the body can help identify genetic differences in a specific enzyme among young adults of East Asian descent.

Quick facts

PhaseNA
Study typeInterventional
Enrollment20 (estimated)
Ages18 Years to 45 Years
SexAll
SponsorStanford University (other)
Locations1 site (Stanford, California)
Trial IDNCT05078723 on ClinicalTrials.gov

What this trial studies

This study investigates the development of a non-invasive screening tool to identify genetic variants of the CYP2C19 enzyme by measuring limonene metabolism. Participants will consume orange peel extract, and changes in limonene levels in their breath will be analyzed to differentiate between individuals with specific CYP2C19 variants and those without. The study focuses on individuals aged 18 to 45 of East Asian descent, as they are more likely to carry these genetic variants. The goal is to improve the understanding of drug metabolism in relation to genetic differences.

Who should consider this trial

Good fit: Ideal candidates for this study are East Asian individuals aged between 18 and 45 years.

Not a fit: Patients outside the specified age range, non-East Asian descent, or with certain medical conditions may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to a simple breath test for identifying individuals at risk of poor drug metabolism due to CYP2C19 genetic variants.

How similar studies have performed: While the approach of using limonene metabolism for genetic screening is novel, similar studies have explored genetic variants and drug metabolism with varying success.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age range: Greater than 18 years and less than 45 years.
* Gender: Male or Female
* Ethnicities: East Asian

Exclusion Criteria:

* 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

Where this trial is running

Stanford, California

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: CYP2C19 Genetic Variants

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.