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®.
Study Type
OBSERVATIONAL
Enrollment
12
12 hours overnight urine (9 pm - 9 am) will be collected. First morning voids will be collected separately in order to be also analysed independently from the 12 hours collection. 24 hours before the 12 hours overnight urine collection, volunteers will be asked to refrain from alcohol consumption and methylxanthine-containing beverages and foods. After the 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®.
12 hours overnight urine (9 pm - 9 am) will be collected. First morning voids will be collected separately in order to be also analysed independently from the 12 hours collection. 24 hours before the 12 hours overnight urine collection, volunteers will be asked to refrain from alcohol consumption and methylxanthine-containing beverages and foods. After the 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®.
12 hours overnight urine (9 pm - 9 am) will be collected. First morning voids will be collected separately in order to be also analysed independently from the 12 hours collection. 24 hours before the 12 hours overnight urine collection, volunteers 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 the 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®.
12 hours overnight urine (9 pm - 9 am) will be collected. First morning voids will be collected separately in order to be also analysed independently from the 12 hours collection. 24 hours before the 12 hours overnight urine collection, volunteers will be asked to refrain from alcohol consumption and methylxanthine-containing beverages and foods. After the 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®.
Geneva University Hospitals
Geneva, Switzerland
Validation LC-MS/MS analytical method
Validation of the LC-MS/MS analytical method for simultaneous quantification of endogenous melatonin and 6-hydroxymelatonin in urine samples
Time frame: 1 month
Intra- and inter-variability
Assess intra- and inter-variability of the urinary metabolic ratio (UMR) 6-hydroxymelatonin/melatonin at three different time (day 1, day 4 and day 30)
Time frame: 3 days (day 1, day 4 and day 30)
Urine correlation
Assess correlation between 12 hours overnight urine and first morning voids samples
Time frame: 4 days (day 1, day 4, day 15 and day 30)
Correlation melatonin and caffeine
Assess correlation between the endogenous UMR 6-hydroxymelatonin/melatonin and the paraxanthine/caffeine ratio in dried blood spot (DBS)
Time frame: 4 days (day 1, day 4, day 15 and day 30)
Impact caffeine intake
Assess impact of caffeine intake on the UMR 6-hydroxymelatonin/melatonin (day 15) before and after caffeine abstinence (fold-change measurements)
Time frame: 1 day (day 15)
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