Use of Endogenous Melatonin and 6-hydroxymelatonin as Biomarkers for CYP1A2

An observational study comprising 4 sessions will be conducted in 12 healthy volunteers. During each study session (sessions 1 to 4), a 12-hour urine collection during the night (21h-9h) will be carried out by each participant. The first urine in the morning will be collected separately to be analysed independently of the 12-hour collection. 24 hours before the start of the night urine collection, volunteers will be asked to refrain from consuming alcohol and caffeinated drinks/foods, with the exception of session 3. Conversely, in session 3, subjects will be asked to drink or eat caffeinated food/drinks 24 hours prior to night-time urine collection (at least one cup of coffee or a can of Coca-Cola®).

After each 12-hour urine collection (around 9:00 a.m.), subjects will be given a cup of coffee or a can of Coca-Cola®. Capillary blood samples (10 μL) will be taken from the fingertips 2 hours after the coffee or Coca-Cola®.