Uva ursi is a trailing evergreen shrub indigenous to northern temperate zones. It is now distributed throughout regions as diverse as the Iberian peninsula, Europe, North America, Siberia, and the Himalayas. Uva ursi flourishes in alpine coniferous forests, and it is widespread in the Scottish Highlands. Like other members of the heath family, it thrives in humus-rich soils.

This plant has a long history of medicinal use dating back to Galen around the 2nd century A.D. The leaves (rather than the berries) of uva ursi were frequently employed as an astringent, mild diuretic, and treatment for urinary tract infections. Native Americans extolled its virtues for remedying inflammation of the urinary tract, including cystitis. In 19th century America, uva ursi was a popular therapy for painful urinary tract disorders. Until the advent of sulfa drugs and antibiotics, uva ursi remained the treatment of choice for bladder infections in the United States.

Pharmacological studies show unequivocally that uva ursi has bacteriostatic properties. Structure-function studies reveal that arbutin, the chief active compound in uva ursi, hydrolyzes in the intestinal tract to form hydroquinone. The antiseptic and astringent effects of this plant are due to the hydroquinone derivatives of arbutin. These compounds exhibit urinary antiseptic effects only if the urine is alkaline. Maintaining an alkaline urine with uva ursi, however, requires adherence to a strict diet of vegetables, potatoes, and nonacidic fruits and juice.

A triterpenoid and flavonoid are responsible for diuretic activity, although the diuretic action of this plant is actually minimal. Nonetheless, the research findings as a whole provide a compelling pharmaceutical rationale for the efficacy of uva ursi in treating various bladder and kidney infections.

Hydroquinone is potentially poisonous, however. Consequently, uva ursi should be consumed in limited quantities and only for a duration of a few days. The potential toxicity, in concert with dietary restrictions, places a limit on the utilization of uva ursi as a practical drug for urinary tract infections.

Uva ursi is adwarf, evergreen perennial that grows up to a elevations of 3,000 m. A single long, fibrous main root gives off short, creeping, red-brown branches that coalesce in a dense mat. The small leaves are alternate, obovate to spatulate, entire-margined, and broadened at the tips. The leaves have a characteristic leathery texture with a dark green upperside. The underside is defined by distinctive reticulate veins. The pink or white flowers are small and bell-shaped, and appear in sparse terminal clusters that bloom in spring. The fruits are shiny, bright red or pink globose pea-sized berries. Though edible, they are sour to the taste.

• Leaves 

Flavonoids (e.g., myricetin, quercetin, plus their glycosides, including hyperin, isoquercitrin, myricitrin, and quercitrin; iridoids (monotropein, putatively asperuloside); quinones (principally arbutin and methyl-arbutin [glycosides]); smaller amounts of piceoside, free hydroquinone, free methoxyphenol; hydrolysable-type tannins; ellagic and gallic acids; terpenoids; malic and quinic acids; allantoin; resin; volatile oil (trace); wax.

Available as crushed leaf or powder preparations containing 400 to 840 mg water-free arbutin per 10 to 12 g drug.

Traditional uses: Cystitis, urinary antiseptic, astringent, diuretic

Conditions: Infections and inflammatory conditions of the urinary tract

Clinical applications: Urinary antiseptic and astringent

Most of the pharmacological investigations of uva ursi have centered on arbutin. In several studies, however, whole-plant extracts were shown to exhibit greater antibacterial action than arbutin alone. This presumably occurred because arbutin, when administered as a single agent, is degraded in the intestines before it can be absorbed. It cannot be converted into its active aglycon form, hydroquinone, until it is absorbed intact from the intestinal tract. Crude plant extracts may enhance the absorption of arbutin by inhibiting cleavage of its glucosidase in the intestines before it can be metabolized.

In in vivo studies, uva ursi elicited antimicrobial activity against Proteus vulgaris, Escherichia coli, Ureaplasma urealyticum, Mycoplasma hominis, Staphylococcus aureus, Pseudomonas aeruginosa, Friedlander's pneumonia, Enterococcus faecalis, Streptococcus strains, and Candida albicans. The minimal inhibitory concentration calculated for arbutin against microorganisms such as these is 0.4 to 0.8%. While these studies support the urinary antiseptic activity of uva ursi, human research is needed to assess its clinical benefits.

In other in vivo research, uva ursi produced anti-inflammatory effects in rat paw edema tests. However, it had no effect on uterotonic activity in vitro. In another study, hydroquinone was more cytotoxic to rat hepatoma cells than agents like azauridin or colchicine, but less cytotoxic than valtrate from valerian (Valeriana officinalis).

• Standard dose: 10 to 12 g crushed leaf or powder (400 to 840 mg hydroquinone derivatives as water-free arbutin) daily 
• Dry extract: 100 to 210 mg hydroquinone derivatives (as water-free arbutin) daily to qid 
• Fluid extract (1:1 g/ml): 3 ml (corresponding to 400 to 840 mg arbutin) daily to qid
• Tincture (1:5): 3 ml tid to qid 

Uva ursi is considered generally safe when administered in standard therapeutic dosages. Side effects have been reported, however, and include irritability, motor restlessness, insomnia, nausea, vomiting, headaches, urinary complaints, and tachycardia. Higher doses can lead to drug dependence and marked elevations in cardiac arrhythmia. Excessive dosage can also cause inflammatory and irritable conditions of the bladder and urinary tract mucous membranes. Uva ursi may produce concomitant problems of hepatotoxicity, especially in children, related to the release of hydroquinones during the metabolic conversion of arbutin.

Uva ursi is contraindicated for lactating women because arbutin and hydroquinone may be released into breast milk; further research is needed to confirm that this actually occurs. Uva ursi is also contraindicated in pregnant women and children under 12 years of age. The tannin levels in this plant may predispose individuals with gastric sensitivity to nausea and vomiting.

Uva ursi should also be avoided by individuals with anxiety, hypertension, glaucoma, impaired cerebral circulation, benign prostate tumor with residual urine accumulation, pheochromocytoma (adrenal medulla or sympathetic paraganglia tumor), and thyrotoxicosis (Graves' disease).

Long-term may be contraindicated because of the possible toxicity of hydroquinone. Uva ursi tea is contraindicated for prolonged periods unless taken under the supervision of a qualified health care provider. Preparations containing arbutin should be limited to a maximum duration of one week for no more than five times a year.

Because uva ursi is efficacious only in alkaline urine, persons taking oral preparations of uva ursi should not consume highly acidic foods, including acidic fruits and fruit juices.

Uva ursi (100 mg/kg 50% methanolic extract po) increased the inhibitory effect of prednisolone on picryl chloride-induced swelling in mice (Kubo et al. 1990). Arbutin, a compound isolated from the leaves of uva ursi, may be responsible for the anti-inflammatory effects of this herb. In another mouse study, arbutin (10 or 50 mg/kg) potentiated the effects of prednisolone and dexamethasone on picryl chloride-induced contact dermatitis (Matsuda et al. 1990). Similar results were obtained with a water extract of uva ursi that also enhanced the ability of dexamethasone ointment (0.005 or 0.025%) to inhibit picryl-chloride-induced contact dermatitis in mice (Matsuda et al. 1992).

Arbutin (50 mg/kg po) increased the anti-inflammatory activity of indomethacin on picryl chloride-induced contact dermatitis, sheep red cell delayed type hypersensitivity, carrageenin-induced edema, and adjuvant-induced arthritis in mice (Matsuda et al. 1991). Clinical studies are needed to confirm whether uva ursi could potentiate the effects of anti-inflammatory medications in humans.

In Britain, uva ursi is an entry on the General Sale List, Schedule 2. It is approved by the German Commission E and accepted for specified indications in France.

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