Slippery Elm

Summary and Pharmaceutical Comment

The primary constituent in slippery elm is mucilage, thereby justifying the herbal use of the remedy as a demulcent, emollient and antitussive. There is, however, a lack of documented scientific evidence to support the use of slippery elm. The mucilage component of slippery elm is unlikely to cause toxicity, although slippery elm has other constituents, not all of which are documented. The use of slippery elm as a food flavouring agent has not been recommended because of insufficient information to assess potential toxicity. In view of the lack of information, the appropriateness of medicinal use of slippery elm should be considered. Excessive use, at least, should be avoided. Slippery elm should not be used during pregnancy and breastfeeding. The potential for slippery elm preparations to interact with other medicines should be considered. The supply of whole bark is controlled by regulations.

Species (Family)

Ulmus rubra Muhl. (Ulmaceae)

Synonym(s)

Ulmus fulva Mich.

Part(s) Used

Bark (inner)

Pharmacopoeial and Other Monographs

BHC 1992(G6)

BHP 1996(G9)

Martindale 35th edition(G85)

Legal Category (Licensed Products)

GSL.(G37) Whole (unpowdered) slippery elm is controlled by regulations.(1)

Constituents

The following is compiled from several sources, including General References G6 and G59.

Carbohydrates Mucilage (major constituent) consisting of hexoses, pentoses, methylpentoses, at least two polyuronides, and yielding on hydrolysis galactose, glucose and fructose (trace), galacturonic acid, L-rhamnose and D-galactose.(2)

Other constituents Tannins 3.0–6.5% (type unspecified), phytosterols (b-sitosterol, citrostadienol, dolichol), sesquiterpenes, calcium oxalate and cholesterol.

Food Use

Slippery elm is listed by the Council of Europe as a natural source of food flavouring (category N3). This category indicates that

there is insufficient information available to make an adequate assessment of potential toxicity.(G16)

Herbal Use

Slippery elm is stated to possess demulcent, emollient, nutrient and antitussive properties. Traditionally, it has been used for inflammation or ulceration of the stomach or duodenum,

convalescence, colitis, diarrhoea and locally for abcesses, boils and ulcers (as a poultice).(G6, G7, G8, G64)

Dosage

Dosages for oral administration (adults) for traditional uses recommended in standard herbal reference texts are given below.

Powdered bark 4–16 mL (1 : 8 as a decoction) three times

daily.(G6, G7)

Powdered bark 4 g in 500 mL boiling water as a nutritional supplement three times daily.(G6, G7)

Coarse powdered bark With boiling water as a poultice.(G6, G7)

Liquid extract 5 mL (1 : 1 in 60% alcohol) three times daily.(G6,

G7)

Figure 1 Slippery elm – dried drug substance (powdered bark).

546 Slippery Elm

Side-effects, Toxicity

None documented. However, there is a lack of clinical and preclinical safety and toxicity data for slippery elm and further investigation of these aspects is required.

Contra-indications, Warnings

Drug interactions None documented. In view of the lack of information on the constituents of slippery elm and their pharmacological activities, the potential for slippery elm preparations to interact with other medicines administered concurrently should be considered.

Pregnancy and lactation Whole bark has been used to procure abortions. In view of this and the lack of information on the pharmacological properties of slippery elm, it should not be used during pregnancy and breastfeeding.

Preparations

Proprietary multi-ingredient preparations

Australia: Bioglan Psylli-Mucil Plus; Cal Alkyline; Digestive Aid; Herbal Cleanse; PC Regulax; Travelaide. Canada: Herbal Throat. UK: Modern Herbals Pile; Pileabs; Slippery Elm Skin Soap; Slippery Elm Stomach Tablets; Wood Sap Ointment. USA: Laci Le Beau Throat Care.

References

1The Medicines (Retail Sale or Supply of Herbal Medicines) Order 1977, SI 2130.

2Tamayo C et al. The chemistry and biological activity of herbs used in Flor-Essence™ herbal tonic and Essiac™. Phytotherapy Res 2000; 14: 1–14.

Summary and Pharmaceutical Comment

Squill is characterised by its cardiac glycoside components and unusual flavonoid constituents. The reputed actions of squill as an expectorant, emetic and cathartic can be attributed to the cardioactive components and squill has been used as an expectorant for many years. However, in view of the documented cardioactive and emetic properties of the aglycones, excessive use and use during pregnancy and lactation should be avoided. Red squill is primarily used as a rodenticide.

Species (Family)

Drimia maritima (L.) Stearn (Asparagaceae)

Synonym(s)

Scilla, Sea Onion, Urginea, Urginea maritima (L.) Baker, Urginea scilla Steinh., White Squill

Part(s) Used

Bulb (red and white varieties)

Pharmacopoeial and Other Monographs

BHC 1992(G6)

BHP 1996(G9)

BP 2007(G84)

Complete German Commission E(G3)

Martindale 35th edition(G85)

Legal Category (Licensed Products)

GSL(G37)

Constituents

See References 1 and 2 and General References G6 and G62.

Cardiac glycosides Scillaren A and proscillaridin A (major constituents); others include glucoscillaren A, scillaridin A, scillicyanoside, scilliglaucoside, scilliphaeoside, scillicoeloside, scillazuroside and scillicryptoside. Scillaren B represents a mixture of the squill glycosides.

Flavonoids Apigenin, dihydroquercetin, isovitexin, iso-orientin, luteolin, orientin, quercetin, taxifolin and vitexin.

Other constituents Stigmasterol, tannin, volatile and fixed oils.

Food Use

The Food Additives and Contaminants Committee (FACC) recommended that squill be prohibited as a food flavouring.(G45)

Herbal Use

Squill is stated to possess expectorant, cathartic, emetic, cardioactive and diuretic properties. Traditionally, it has been used for chronic bronchitis, asthma with bronchitis, whooping

cough, and specifically for chronic bronchitis with scanty

sputum.(G6, G7, G8, G64)

Dosage

Dosages for oral administration (adults) for traditional uses recommended in older and contemporary standard herbal and pharmaceutical reference texts are given below.

Dried bulb 60–200 mg as an infusion three times daily.(G6, G7)

Squill Liquid Extract (BPC 1973) 0.06–0.2 mL.

Squill Tincture (BPC 1973) 0.3–2.0 mL.

Squill Vinegar (BPC 1973) 0.6–2.0 mL.

Pharmacological Actions

The aglycone components of the cardiac glycoside constituents possess digitalis-like cardiotonic properties.(G41) However, the squill aglycones are poorly absorbed from the gastrointestinal tract and are less potent than digitalis cardiac glycosides.(1, 2)

Expectorant, emetic and diuretic properties have been documented for white squill.(G41) Squill is reported to induce vomiting by both a central action and local gastric irritation.(1, 2) Subemetic or near-emetic doses of squill appear to exhibit an expectorant effect, causing an increase in the flow of gastric secretions.(1, 2)

S

Figure 1 Selected constituents of squill.

Figure 2 Squill (Drimia maritima).

Antiseborrhoeic properties have been documented for methanol extracts of red squill which have been employed as hair tonics for the treatment of chronic seborrhoea and dandruff.(G41)

Squill extracts have been reported to exhibit peripheral vasodilatation and bradycardia in anaesthetised rabbits.(1, 2)

Side-effects, Toxicity

Clinical data

Excessive use of squill is potentially toxic because of the cardiotonic constituents. However, squill is also a gastric irritant and large doses will stimulate a vomiting reflex.

Preclinical data

Red squill is toxic to rats and is mainly used as a rodenticide, causing death by a centrally induced convulsant action.(1, 2) A squill soft mass (crude extract) has been stated to be toxic in

S

Figure 3 Squill – dried drug substance (bulb).

guinea-pigs at a dose of 270 mg/kg body weight. A fatal dose for Indian squill (Urginea indica Kunth.) is documented as 36 mg/kg.

Contra-indications, Warnings

Squill may cause gastric irritation and should be avoided by individuals with a cardiac disorder. In view of the cardiotonic constituents, precautions applied to digoxin therapy should be considered for squill.

Drug interactions None documented. However, the potential for preparations of squill to interact with other medicines administered concurrently, particularly those with similar or opposing effects, should be considered. Squill contains cardiac glycosides, and interactions listed for digoxin should be considered for squill.

Pregnancy and lactation Squill is reputed to be an abortifacient and to affect the menstrual cycle.(G30) In addition, cardioactive and gastrointestinal irritant properties have been documented. The use of squill during pregnancy and lactation should be avoided.

References

1 Court WE. Squill – energetic diuretic. Pharm J 1985; 235: 194–197.

2Anon. Squill: Lawrence Review of Natural Products. Levittown, Pennsylvania: Pharmaceutical Information Associates Ltd, 1989.