Horse Chestnut Seed

The fruit of the horse chestnut tree contains large seeds with a shiny, brown coat. The unprocessed seeds are toxic when ingested, and are not to be confused with the edible fruit of the sweet chestnut, Castanea sativa.

Uses and Benefits:

The processed seeds are employed in a standardized horse chestnut seed extract (HCSE), which is a popular oral therapy in European countries for chronic venous insufficiency and localized edema. Aescin, the active constituent of HCSE, is a registered drug in Germany and other European countries and is used topically and intravenously. Topical HCSE and aescin preparations are alleged to decrease symptoms of varicose veins, superficial thrombophlebitis, lymphatic edema, hemorrhoids, hematomas, and a variety of sports injuries and other traumas.

Traditionally, horse chestnut seeds have been used for arthritis and rheumatic conditions, neuralgia, rectal complaints, and other related disorders of inflammatory congestion and engorgement. The bark and leaves of the plant have also been used medicinally.

Pharmacology:

The primary active constituent of horse chest­nut seeds is aescin (also spelled escin), which is a complex mix­ture of over 30 triterpene saponin glycosides. Other constituents include flavonoids, condensed tannins, sterols, and fatty acids. Saponin glycosides are poorly absorbed; aescin's oral bioavail­ability is less than 1 % of its intravenous dose. In a number of animal and human pharmacologic studies, aescin and HCSE have been demonstrated to decrease capillary permeability and

Clinical Trials:

Similar benefits were found in RCTs of pregnant women with lower extremity edema and in healthy subjects on a long-dis­lance plane flight. Although not adequately blinded, an RCT of patients with chronic venous insufficiency found HCSE and compression stockings to have equivalent activity in decreasing leg volume measured by plethysmography (-43.8 ml and -46.7 ml, respectively, compared to +9.8 ml with placebo) after 12 weeks of therapy.

In a well-designed U.S. double-blind RCT of 70 healthy volunteers, a 2% aescin topical gel significantly reduced tenderness of experimentally induced hematomas compared to placebo (P < 0.001).

Adverse Effects:

The side effects of oral HCSE are mild and infrequent. Incidence of mild gastrointestinal symptoms, headache, dizziness, and allergic reactions ranged from 0.9% to 3% in the controlled clinical trials, and the frequency was not significantly different from that of placebo in three trials. Products that are not controlled-release or enteric coated may produce more gastrointestinal upset.

Side Effects and Interactions:

There are no recognized drug interactions with HCSE.

Cautions:

Parenteral administration of aescin or horse chestnut products on rare occasions has been associated with severe renal, hepatic, and anaphylactic reactions. Unprocessed horse chestnut seeds are poisonous and can cause severe gastroin­testinal and neurotoxic reactions. There are no embryotoxic or teratogenic effects of aescin in animal models ; however, safety of HCSE has not been established in pregnant or breast feeding women.

Preparations & Doses:

Oral HCSE products based on German standards contain 16-20% triterpene glycosides, calculated as aescin. The usual recommended daily dose, and the most common dose used in the clinical trials, is 50 mg b.i.d. of aescin; this is equivalent to 600 mg/day of the standardized HCSE.The standardized commercial preparation employed in most of the European controlled trials (Venostasin) is marketed in the U.S. as Venostat (Pharmaton/Boehringer Ingelheim).

Summary Evaluation

Standardized HCSE is a well-tolerated herbal medicine that appears to be useful for the treatment of chronic venous insuffi­ciency based on a number of controlled clinical trials. Benefits have not been adequately compared to standard therapies such as compression stockings and/or diuretics, but oral HCSE could be tried as an adjunctive or alternative therapy. Topical aescin or HCSE may be useful for localized areas of inflammation or edema, but controlled clinical studies are lacking.