Development of a method to evaluate the function of metabolizing enzyme CYP1A2

Exploratory study of a new phenotyping method for the evaluation of CYP1A2 activity - Exploratory study to evaluate CYP1A2 activity

Status

Active, not recruiting

Phases

Unknown

Study type

Interventional

Source

JPRN

Registry ID

JPRN-UMIN000049052

Enrollment

Registered

2022-10-01

Start date

2022-10-01

Completion date

Unknown

Last updated

2026-06-29

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

healthy subject

Interventions

Caffeine intake from food

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: Persons who have given consent for this study

Exclusion criteria

Exclusion criteria: 1) Persons who do not consume caffeine-containing products (coffee, tea, soft drinks) on a daily basis (2 to 3 times a week). 2) Persons who have experienced adverse reactions (palpitations, nausea, etc.) to caffeine-containing products (coffee, tea, soft drinks). Persons who are allergic to caffeine 3) Persons who have ever felt sick from blood sampling. 4) Persons who are under medical treatment, pregnant women or those who are thought to be pregnant or nursing 5) Persons who have subjective symptoms of hyperacidity on interview, persons who have been diagnosed with heart disease or gastric ulcer

Design outcomes

Primary

Measure	Time frame
Melatonin pharmacokinetic parameters (melatonin 6-hydroxy metabolic clearance, plasma 6-hydroxy melatonin/melatonin ratio)	—

Secondary

Measure	Time frame
Caffeine pharmacokinetic parameters (caffeine clearance, plasma caffeine/paraxanthine ratio)	—

Countries

Japan

Contacts

Public ContactAkitomo Yokokawa

School of Pharmacy, Tokyo University of Pharmacy and Life Sciences Laboratory of Clinical Chemistry and Experimental Therapeutics

yokokawa@toyaku.ac.jp042-676-5803

Outcome results

None listed

Source: JPRN (via WHO ICTRP) · Data processed: Jul 3, 2026