Stimulant Laxatives

Botanical stimulant laxatives all generally contain a class of compounds referred to as anthraquinone glycosides. Once ingested and activated by bacterial metabolism in the human gut, these molecules promote water retention in the stool and stimulate increased peristalsis in the large intestines.

Aloes

Aloes powder is the solid residue obtained by evaporating the liquid which drains from the transversely cut leaves of Cape Aloes (Aloe ferox). The juice is usually concentrated by boiling and solidifies upon cooling. It is characteristically dark-brown or greenish-brown. It has a sour odor; the taste is bitter. Cape Aloes is found primarily on the Cape Horn of South Africa where it can typically grow 6-10 feet tall. The best-characterized constituent of the resin is aloin, one of the compounds in the family of anthraquinone glycosides. Other similar quinones are also present. It is thought that aloin and similar derivatives are converted into emodin-derivatives within the gastrointestinal tract and then these act as purging laxatives (65-68) Aloes' effect is primarily caused by its influence on the motility of the colon- an inhibition of stationary and stimulation of propulsive contractions. This results in an accelerated intestinal passage and, because of the shortened contraction time, a reduction in liquid absorption. In addition, stimulation of active chloride secretion increases the water and electrolyte content in the stool. The preparations of aloes have been in the U.S. Pharmacopoeia for over 100 years and it has a positive Commission E monograph where it is listed for short-term constipation.

Despite aloes long-term use and reputation as the most potent natural laxative, cascara sagrada and senna seem to be more popular because of the commonly held notion that aloes is more often associated with side-effects such as cramping and nausea. This however has not been the case when used in recent decades as a dietary supplement and likely is attributed to information passed on from the use of preparations nearly a century ago.

Dosing aloes is different depending on the individual. The optimum dose is the smallest dosage necessary to obtain a soft stool that passes without difficulty. For many individuals this is one 250 mg capsule, although many may need 450 mg or more to obtain this effect. Twenty four hours should be allowed to pass before the next dose is administered. Aloes should not be used during pregnancy because of its uterine stimulant potential. Anthroquinones are known to be secreted in breast milk of nursing mothers and this may purge the child along with the mother. As with all stimulant laxatives, aloes should not be used for longer than 2 weeks for most individuals.

Cascara Sagrada

Considered GǣsacredGǥ bark by those using it, cascara sagrada describes the small to medium-sized tree Rhamnus purshiana (or Frangula purshiana). The primary use for cascara sagrada is as a laxative, and has a long history of use among Native Americans and Western herbalists. The German Commission E has a positive therapeutic monograph for laxative formulas with a dose corresponding to 20-30 mg cascaroside A (or equivalent).

Senna

The dried leaflets and pods of Cassia senna (or related species), is most often referred to medicinally as senna. These preparations contain the strong glycosides sennoside A and B. The laxative preparation for senna has been used in medicinal teas in Europe, and powdered extracts have become very popular in OTC medications here in the U.S. The typical dose is 0.6-2 grams (equivalent to 20-30 mg of sennoside B). Senna also has a positive Commission E monograph for use in laxative formulations. Similar activities are found in Rhubarb root preparations (Rheum officinale), although rhubarb is more commonly used in Asia.

Cautions With Stimulant Laxatives

The use of botanical stimulant laxatives should be considered only after diet, lifestyle, and bulk laxatives have proven ineffective, and other causes have been ruled out. They are contraindicated in cases of bowel obstruction, acute intestinal inflammation and abdominal pain of unknown origin. They should not generally be used in children under 12 or in pregnant or nursing women.

Overuse and abuse of laxatives is common. Potential dangers include electrolyte imbalance, especially potassium deficiency which can lead to muscle weakness and heart function disorders. This potassium imbalance can be further exacerbated by the use of thiazide diuretics, corticoadrenal steroids or high doses of licorice root. Chronic use of anthraquinone glycosides has been associated with an increased pigmentation of the intestinal mucosa called pseudomelanosis coli. While this has been determined to be a benign condition, it is diagnostic for laxative abuse and often alters the ability to diagnose other colon diseases. While the available evidence is divided on whether chronic use of stimulant laxatives will result in a condition of a GǣsluggishGǥ colon, all attempts should be made to move to bulk-forming laxatives and refrain from chronic use of stimulant laxatives.