title: Urinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract as film-coated tablets and aqueous solution in healthy humans.
abstract: Bearberry leaves and preparations made from them are traditionally used for urinary tract infections. The urinary excretion of arbutin metabolites was examined in a randomized crossover design in 16 healthy volunteers after the application of a single oral dose of bearberry leaves dry extract (BLDE). There were two groups of application using either film-coated tablets (FCT) or aqueous solution (AS). The urine sample analysis was performed by a validated HPLC coolarray method (hydroquinone) and a validated capillary electrophoresis method (hydroquinone-glucuronide, hydroquinone-sulfate). The total amounts of hydroquinone equivalents excreted in the urine from BLDE were similar in both groups. With FCT, 64.8% of the arbutin dose administered was excreted; with AS, 66.7% was excreted (p = 0.61). The maximum mean urinary concentration of hydroquinone equivalents was a little higher and peaked earlier in the AS group versus the FCT group, although this did not reach statistical significance (Cur max = 1.6893 micromol/ml vs. 1.1250 micromol/ml, p = 0.13; tmax (t midpoint) = 3.60 h vs. 4.40 h, p = 0.38). The relative bioavailability of FCT compared to AS was 103.3% for total hydroquinone equivalents. There was substantial intersubject variability. No significant differences between the two groups were found in the metabolite patterns detected (hydroquinone, hydroquinone-glucuronide, and hydroquinone-sulfate).
authors.affiliation: Friedrich-Alexander University, Erlangen-Nuremberg, Department of Medicine I, Erlangen, Germany.
authors.forename: Gernot
authors.initials: G
authors.lastname: Schindler
authors.forename: Ulrich
authors.initials: U
authors.lastname: Patzak
authors.forename: Benno
authors.initials: B
authors.lastname: Brinkhaus
authors.forename: Alexander
authors.initials: A
authors.lastname: von Niecieck
authors.forename: Jörg
authors.initials: J
authors.lastname: Wittig
authors.forename: Nils
authors.initials: N
authors.lastname: Krähmer
authors.forename: Ingmar
authors.initials: I
authors.lastname: Glöckl
authors.forename: Markus
authors.initials: M
authors.lastname: Veit
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001104:Arbutin / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine*; D029792:Arctostaphylos / Q000737:chemistry; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D006873:Hydroquinones / Q000378:metabolism / Q000652:urine; D008297:Male; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D018515:Plant Leaves / Q000737:chemistry; D012996:Solutions / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013607:Tablets / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D006873:Hydroquinones; D010936:Plant Extracts; D012996:Solutions; D013607:Tablets; D001104:Arbutin