Cascara Sagrada

Description

Cascara Sagrada (Rhamnus Purshiana), Family: Anacardiaceae

Common Names:

Habitat: found in Europe and western Asia, and in North America, from northern Idaho to the Pacific coast; mountainous areas.

Description: Cascara sagrada is a small deciduous tree that grows from 15-20 feet in height. It has pubescent stems covered with reddish-brown bark and often gray lichen. The tree bears dark green elliptic to oblong-ovate leaves with prominent veins and toothed margins. The leaves are rounded at the base and have somewhat hairy undersides. Short-stemmed clusters of small, greenish-white flowers grow from the upper leaf axils; they eventually produce black, pea-sized drupes that are poisonous.

Medicinal parts: bark- dried, collected at least a year before use.

CHEMICAL COMPOSITION

* For definition of some of the above terms see the dictionary section of this book.

FOLKLORE

Cascara sagrada is perhaps the most common laxative used in both herbal medicine and orthodox pharmacy. It is technically classified as a stimulant laxative, since in induces peristalsis.

The active constituents of cascara are the anthraquinones. They are inactive in the gastrointestinal tract until they reach the colon; there they produce a soft or formed stool within about six to eight hours and cause vigorous peristalsis.

One of the most common uses of cascara is to correct habituation to other laxatives by restoring intestinal tonus. In smaller amounts, the herb has proven effective in the treatment of liver disorders and gallstones. The anthraquinones have potent antibacterial properties; they have been used against leukemia and as immunosuppressants during skin graft operations. Cascara constituents have also served as chelating agents in the prevention of urinary stones.

Cascara does not lose efficacy with repeated use. For the most part, cascara is nonaddictive, and only really heavy abuse, which is rare, produces "cathartic colon." Normally, its main side-effect is griping. The herb may have other physiological effects as well, due to one or more of its numerous constituents (e.g., tri- and dihydroxyanthraquinones - emodin, fragulin, iso-emodin, aloe-emodin, and chrysophaol - and rhein, and aloins).

METHOD OF ACTION

There is presently insufficient data on this subject.

DRUG INTERACTIONS

Known Interactions

Due to its cathartic activity, cascara sagrada may potentiate anticoagulant therapy by reducing absorption of vitamin K from the gut. It may also inhibit absorption of dextrose from the intestines.

This cathartic herb decreases intestinal transit time. Therefore, cascara sagrada may inhibit the absorption of digitalis glycosides, and decrease their cardiac action. Cathartic-induced hypokalemia, however, increases the toxicity and potency of absorbed digitalis, as well as potentiates muscle relaxants.

In addition to the specific interactions listed, the cathartic action of cascara sagrada tends to hasten the passage of all oral medications through the gut, thereby inhibiting their action.

Possible Interactions

Laxative-induced diarrhea may result in decreased absorption of isoniazid. The same is true with sulfisoxasole, but this appears to be a clinically unimportant interaction effect.

Comments

Laxatives induce increased speed of intestinal emptying, which may result in decreased absorption of vitamin K and/or anticoagulants.