MAJOR CHEMICAL CONSTITUENTS

The primary medicinally active constituent is arbutin, a phenolic glycoside that generates hydroquinone as a result of glycolysis. Tannins, and flavonoids are also present. A small amount of free hydroquinone is found in the leaves. P-coumaric acid and caffeic acid, compounds with known antibacterial properties, and salicylic acid, a known bacteriostatic and anti-inflammatory agent, may be of significance. Uva ursi contains the flavonoid quercetin and the triterpenes ursolic acid, among many other constituents.

PRINCIPAL USES

TRADITIONAL AND HISTORICAL USES

Uva ursi was used by numerous native tribes of the northern United States and Canada as a diuretic or for treatment of inflammation of the genitourinary tract. It appears to have been introduced into European medical practice in the thirteenth century as a treatment for conditions of the bladder and kidney, and as such has remained in use since. Goethe is reported to have been prescribed and successfully treated for kidney stones with this herb. Early US medical botanists reported on its usefulness in the treatment of genitourinary disorders and by the late nineteenth century it was widely used by Eclectic physicians as an astringent tonic for chronic diarrhea, dysentery, and menorrhagia, as well as for genitourinary disorders and diabetes. It has had an official entry in pharmacopoeias of numerous western nations since the eighteenth century, including the British Herbal Pharmacopoeia, the National Formulary and the United States Dispensatory. It can still be found in the pharmacopoeias of numerous countries including Austria, Czechoslovakia, Egypt, France, Germany, Hungary, Japan, Russia, Switzerland, and others.

IN VITRO, ANIMAL, AND CLINICAL DATA

Uva ursi remains one of the most important and commonly used urinary tract disinfectants in modern herbal medicine, widely used in the treatment of uncomplicated acute and recurrent urinary tract infections. Midwives include the herb as an astringent anti-inflammatory in sitz baths and perineal rinses for postnatal perineal healing and as part of treatment of vaginitis and urethritis. There are few clinical trials or pharmacodynamic studies of uva ursi. In vitro studies using crude leaf preparations and extracts of uva ursi leaf have demonstrated mild antimicrobial activity against known UTI causing

Uva ursi (Arctostaphylos uva ursi).

Photo by Martin Wall.

organisms, including but not limited to C. albicans, E. coli, S. aureus, and Proteus vulgaris, and others. Several studies have also demonstrated antiinflammatory activity of the herb, particularly enhanced when extracts are used in combination with anti-inflammatory pharmaceutical drugs, for example, prednisolone, indomethacin, or dexamethazone.

MECHANISMS OF ACTION

The mechanisms of action of uva ursi are not fully elucidated. It appears, however, that arbutin, and its aglycone, hydroquinone—a urinary disinfectant—are primarily responsible for the herb’s antimicrobial activity. Hydroquinones are primarily hydrolyzed in the kidney because tannins prevent enzymatic activity that would normally lead to its conversion in the gut; it also appears that arbutin might be hydrolyzed in the urinary tract as a result of β-glucosidase activity stimulated by pathogenic infection. Arbutin is rapidly absorbed after consumption of tea and extract preparations, with urinary excretion of metabolites within a few hours and up to 24 hours. Antibacterial actions may be most prominent in an alkaline (pH 8) urinary environment; however, activity is not necessarily dependent on elevated urinary pH.

RATINGS

PREPARATIONS USED CLINICALLY

Uva ursi shows greater antibacterial activity in an alkaline environment; some authors suggest giving it along with sodium bicarbonate or substantially increasing fresh fruit and vegetable consumption during treatment to alkalinize the urine; others suggest avoiding the use of acidifying agents during treatment. Alkalinization of the urine seems not to be a prerequisite to the antiseptic properties of hydroquinone released from arbutin. Some amount of disagreement can be found in the literature regarding the requirement of an alkaline pH environment for the efficacy of this herb. Some authors postulate that a reduced urinary pH inhibits the efficacy of the herb; others argue that increasing the alkalinity of the urinary environment enhances the efficacy of the herb, while still others state that activity is not depend on urinary pH. Given the reliability of this herb generally, it is prudent to conclude that if uva ursi does not seem to be working, the addition of 2 “00” capsules of sodium or potassium bicarbonate may be taken once or twice daily with uva ursi doses, to alkalinize the urine in such situations before making a final determination about efficacy. Some authors recommend discontinuing use of the herb after 7 days; however, the European Scientific Cooperative on Phytotherapy (ESCOP) recommends treatment be continued until complete disappearance of symptoms, up to a maximum of 2 weeks.

DOSAGE

Doses should provide the equivalent of 400 to 840 mg arbutin daily, divided over two to four doses.

USE IN PREGNANCY AND LACTATION

SAFETY INFORMATION: SIDE EFFECTS, CONTRAINDICATIONS, TOXICITY, AND HERB-DRUG INTERACTIONS

Used as per directed dose and duration, uva ursi appears to have a good safety profile.