Buckthorn bark

Frangulae cortex, buckthorn bark, frangula.  

Buckthorn bark consists of the dried bark of the trunks and branches of Rhamnus frangula L.  (syn.   Frangula alnus Miller) [Fam.  Rhamnaceae], as well as its preparations in effective dosage.  

The bark contains anthranoids, mainly of the emodin-physcion and chrysophanol type.  

These drugs must conform to the currently valid pharmacopeia.  

Pharmacological Properties, Pharmacokinetics, Toxicology

1,8-dihydroxy-anthracene derivatives have a laxative effect.  These compounds increase the motility of the colon by inhibiting stationary and stimulating propulsive contractions.  This results in accelerated intestinal passage and, because of the shortened contraction time, a reduction in liquid absorption through the lumen.  In addition, stimulation of active chloride secretion increases the water and electrolyte content of intestinal contents.  

Systematic studies pertaining to the kinetics of buckthorn bark preparations are not available; however, it must be supposed that the aglycones contained in the drug are already absorbed in the upper small intestine.  The -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.  Anthrones are the laxative metabolites.  

Active metabolites of other anthronoids, 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 genotox-icity of buckthorn and its preparations are not available.  Some positive data were obtained for aloe-emodin, emodin, physcion and chrysophanol.  No data are available for their 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 buckthorn bark, e.g., fresh bark, will cause severe vomiting, possibly with spasms.  

Clinical Data

Uses

Constipation.  

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.  

Side Effects

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

With long-term 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.  The potassium deficiency can lead to disorders of heart function and muscular weakness, especially with concurrent use of cardiac glycosides, diuretics and corticosteroids.  

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

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

With chronic use or in cases of abuse of the drug, a potentiation of cardiac glycosides due to a loss of serum potassium is possible.  Also possible is an effect on antiarrhythmic agents.  Potassium deficiency can be increased by simultaneous application of thiazide diuretics, corticosteroids, or licorice root.  

Cut bark, powder or dried 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 glycofrangulin 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 dose.  

Electrolyte and fluid-regulating measures.  

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

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

None known.