Urinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract as film-coated tablets and aqueous solution in healthy humans

J Clin Pharmacol. 2002 Aug;42(8):920-7. doi: 10.1177/009127002401102740.

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).

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Arbutin / administration & dosage
  • Arbutin / metabolism*
  • Arbutin / urine*
  • Arctostaphylos* / chemistry
  • Cross-Over Studies
  • Female
  • Humans
  • Hydroquinones / metabolism
  • Hydroquinones / urine
  • Male
  • Phytotherapy
  • Plant Extracts / administration & dosage*
  • Plant Extracts / chemistry
  • Plant Extracts / metabolism
  • Plant Extracts / pharmacokinetics*
  • Plant Leaves / chemistry
  • Solutions / administration & dosage
  • Solutions / pharmacokinetics*
  • Tablets / administration & dosage
  • Tablets / pharmacokinetics*

Substances

  • Hydroquinones
  • Plant Extracts
  • Solutions
  • Tablets
  • Arbutin