Impact of Food Intake on Berberine Kinetics

All enrolled participants will come under fasting conditions for 10 h to the Clinical Research Unit. Every volunteer will receive a single dose of 1000 mg berberine (two capsules) with 250 ml still water. Intake will be either in the fasting condition, or after a light caloric meal (2 toasts, butter, cheese, marmalade), or a high caloric meal (2 toasts with butter, 2 fried eggs, 2 slices of bacon, 3 hash brown and 240ml of whole milk), respectively. In between these different intakes will be at least one week. The order of fasting - light meal - heavy meal study visits will be randomized.

A total amount of 12 blood samples at defined time points (baseline; 1; 2; 3; 4; 5; 6; 7; 8; 24 h) will be taken. At each time point, blood will be collected in a tube for collecting plasma. In addition, for glucose and insulin measurements, blood samples will be obtained at 4 h, 5 h and 6 h .

Every hour until the meal at noon, participants will drink 100 ml of sparkling water to stimulate the intestinal peristalsis and promote transport of the capsule. Volunteers are asked to stay in bed for four hours after berberine intake but then are allowed to move freely in the Clinical Research Unit. After 2 h participants will be served tea or coffee and after 4 h a meal will be served.

Urine will be collected at the first 8 h after administration. The participants will stay in the Clinical Research Unit of the Institute of Pharmacology for the first 8 hours after administration.

Inclusion criteria

• wildtype genotypes for CYP2D6 and organic cation transporter 1 (OCT-1)
• understands the study purpose and design
• contractually capable and provides signed informed consent form
• healthy condition or mild and/or well treated forms of allergies, asthma, hypertension and orthopedic diseases

Exclusion criteria

• BMI ≤18,5kg/m2 and ≥29,9 kg/m2
• only in women: known pregnancy or lactation period
• only in women: positive pregnancy test at screening or any other study visit
• anemia: Hb < 13 g/dl (8,07 mmol/l) in men or < 12 g/dl (7,45 mmol/l) in women
• elevated liver function tests (ALAT, ASAT, yGT, Bilirubin > 2xULN)
• reduced renal function (eGFRMDRD < 60ml/min/1,7m2)
• currently mentally unstable
• use of recreational drugs more than twice a week
• poor venous conditions that make it impossible to place a peripheral venous catheter and regularly draw blood through it