Cascara Sagrada bark (Rhamni purshianae cortex)

Published November 1, 1984; Replaced July 21, 1993.
List of German Commission E Monographs (Phytotherapy)

Amerikanische Faulbaumrinde

Name of Drug

Rhamni purshianae cortex, cascara sagrada bark.

Composition of Drug

Cascara sagrada bark consists of the dried bark of Rhamnus purshiana D.C. (syn. Frangula purshiana (D.C.) A. Gray ex J.C. Cooper) [Fam. Rhamnaceae], as well as its preparations in effective dosage.

The bark contains anthranoids, mainly of the aloe-emodin type, in addition to those of the chrysophanol and physcion type.

The drug must conform to the currently valid pharmacopeia.

Pharmacological Properties, Pharmacokinetics, Toxicology

1,8-dihydroxy-anthracene derivatives have a laxative effect. This effect is primarily due to the influence of the herb on the motility of the colon, inhibiting stationary and stimulating propulsive contractions. This results in an accelerated intestinal passage and, because of the shortened contact time, a reduction in liquid absorption. In addition, stimulation of the active chloride secretion increases water and electrolyte content.

Systematic studies pertaining to the kinetics of cascara sagrada bark preparations are not available. However, it must be concluded that the aglycones contained in the drug are already absorbed in the upper small intestine. The ß-glycosides are prodrugs which are neither absorbed nor cleaved in the upper gastrointestinal tract. They are degraded in the colon by bacterial enzymes to anthrones. The anthrones are the laxative metabolites.

Active metabolites of other anthro-noids, such as rhein, infiltrate in small amounts into the milk ducts. A laxative effect on nursing infants has not been observed. The placental permeability for rhein is very small.

Drug preparations [i.e., herbal stimulant laxatives] have a higher general toxicity than the pure glycosides, presumably due to the content of aglycones. Experiments pertaining to the genotoxicity of cascara sagrada and its preparations are not available. Some positive data were obtained for aloe-emodin, emodin, physcion and chrysophanol. No data are available for carcinogenicity.

The fresh bark contains free anthrone and must be stored for one year or artificially aged by heat and aeration. The use of illegally processed cascara sagrada bark, e.g., fresh bark, will cause severe vomiting, possibly spasms.

Clinical Data 1. Uses Constipation.

2. Contraindications

Intestinal obstruction, acute intestinal inflammation, e.g., Crohn's disease, colitis ulcerosa, appendicitis, abdominal pain of unknown origin. Children under 12 years of age, pregnancy.

3. Side Effects

In single incidents, cramp-like discomforts of the gastrointestinal tract. These cases require a dosage reduction.

Long-time use/abuse:

Disturbances of electrolyte balance, especially potassium deficiency, albuminuria, and hematuria. Pigment implantation into the intestinal mucosa (pseudomelanosis coli) is harmless and usually reverses upon discontinuation of the drug. Potassium deficiency can lead to disorders of heart function and muscular weakness, especially with concurrent use of heart glycosides, diuretics, or corticosteroids.

4. Special Caution for Use

Stimulating laxatives must not be used over an extended period of time (1 - 2 weeks) without medical advice.

5. Use During Pregnancy and Lactation

Because of insufficient toxicological investigation, this drug should not be used during pregnancy and lactation.

6. Interactions with Other Drugs

With chronic use/abuse, loss in potassium may cause an increase in effectiveness of cardiac glycosides. An effect on antiarrhythmics is possible. Potassium deficiency can be increased by simultaneous application of thiazide diuretics, corticosteroids, and licorice root.

7. Dosage

Cut bark, powder or dry extracts for teas, decoction, cold maceration or elixir. Liquid or solid forms of medication exclusively for oral use.

Unless otherwise prescribed:

20 - 30 mg hydroxyanthracene derivatives daily, calculated as cascaroside A. The individually correct dosage is the smallest dosage necessary to maintain a soft stool.

Note: The form of administration should be smaller than the normal daily dosage.

8. Overdosage

Electrolyte and fluid imbalance.

9. Special Warnings

Use of a stimulating laxative longer than recommended can cause intestinal sluggishness.

The preparation should be used only if no effects can be obtained through change of diet or use of bulk-forming products.

10. Effects on Operators of Vehicles and Machinery

None known.