Taxonomic Class

Solanaceae

Common Trade Names

None known.

Common Forms

Available as an extract of the corkwood tree (leaves and stems) in liquid and tablets.

Source

The active ingredients are extracted from the leaves, stems, and root bark of Duboisia myoporoides, which is native to Australia.

Chemical Components

The corkwood tree is a rich source of alkaloids and has been used as a commercial source of scopolamine. The major alkaloids found in young leaves and stems are scopolamine and valtropine; other alkaloids­hyoscyamine, trigloyl tropine, and valeroidine-occur in lesser quantities. Alkaloids extracted from older leaves and stems include acetyl tropine, apohyoscine, butropine, hyoscyamine, isoporoidine, noratropine, poroidine, scopolamine, tropine, valeroidine, and valtropine. The young root and bark of the tree yield apohyoscine, atropine, hyoscyamine, scopolamine, tropine, valeroidine, and valtropine. Similar alkaloids are found in old root and bark samples. Nicotine and nornicotine have also been reported in the leaves .

Actions

Scopolamine and the other alkaloids found in corkwood are antimuscarinics or muscarinic-cholinergic blockers and exhibit a wide range of pharmacologic effects. When taken in therapeutic doses, scopolamine may cause drowsiness and a dreamlike state. Larger doses can result in excitement or restlessness and hallucinations. These antimuscarinics may also affect heart rate, reduce gastric and salivary secretions and GI motility, and cause mydriasis and blurred vision because of cycloplegia.

Reported Uses

The corkwood tree was principally used as a main source of scopolamine and atropine before the availability of other commercial sources.

Scopolamine is commonly used to prevent motion-induced nausea and vomiting, and atropine has limited use in treating GI motility disturbances. It has been reported that corkwood leaves are cured, rolled into a quid, and chewed by native Australians for their stimulant effects and used in hunting to stun animals. Extracts of the leaves have been used medicinally as a substitute for atropine. Quids are chewed to ward off hunger, pain, and tiredness. Alkaloids from the plant are used as a therapeutic substitute for atropine.

Dosage

No consensus exists.

Adverse Reactions

CNS: disorientation, drowsiness, euphoria, excitation (in high doses), fatigue, hallucinations (in high doses).

CV: alterations in heart rate.

EENT: blurred vision, cycloplegia, dry mouth.

GI: constipation.

GU: urine retention.

Skin: dry skin.

Interactions

Amantadine, beta blockers, digoxin, tricyclic antidepressants and other drugs with anticholinergic or anticholinergic-like effects: Increased anticholinergic-like effects. Avoid administration with corkwood.

Contraindications And Precautions

Corkwood and its products are contraindicated in patients who are hypersensitive to antimuscarinics; in those with CY disease, glaucoma, myasthenia gravis, obstructive GI conditions, obstructive uropathy or renal disease, or other conditions that may be exacerbated by antimuscarinics; and in pregnant or breast-feeding patients.

Special Considerations

Adverse reactions from corkwood alkaloids are related to their antimuscarinic action.

Consider exposure to corkwood if the patient manifests pupillary, vision, or behavioral changes.

Advise the patient who is already receiving anticholinergic-like drugs to avoid taking corkwood because of the risk of increased anticholinergic effects.

Caution the patient who may be at risk for disease exacerbation or adverse effects from anticholinergic drugs against using corkwood.

Advise women to avoid using corkwood during pregnancy or when breast -feeding.

Commentary

Although corkwood leaves and stems have been used for medicinal purposes, primarily as an atropine substitute, no clinical studies of the plant have been undertaken. Antimuscarinic toxicity has been reported after occupational or accidental exposure, with absorption through the mucous membranes and upper respiratory tract. Medicinal use of the plant is not recommended.