Nature’s Way Uva Ursi Standardized Description: Urinary Tonic Standardized To: 20% Arbutin Uva Ursi (arctostaphylos uva-ursi) was first used by welsh physicians in the 13th century. Uva Ursi Extract is standardized to 20% arbutin. Based on the antiseptic action of the leaves, Uva Ursi was listed in the U.S. Pharmacopeia and National Formulary from 1820-1950. Disclaimer These statements have not been evaluated by the FDA. These products are not intended to diagnose, treat, cure, or prevent any disease.