Asclepias curassavica 馬利筋

POISONOUS PARTS

Whole plant, especially the latex.³

TOXICITY

• Toxic Constituents

  Cardiac glycosides such as calotropin and uscharin.^4–8

• Toxic Dose

  Local contact of small amount of latex can cause eye symptoms.³

• Mechanism

  Cardiac glycosides inhibit Na⁺/K⁺-ATPase of the myocardium, increase its excitability and may lead to arrhythmias. Topical administration of cardiac glycosides can cause corneal oedema and blurred vision by inhibiting endothelial Na⁺/K⁺-ATPase.^3,9

• Poisoning Features

  Eye contact: digitalis keratopathy. Ingestion: digitalis-like toxicity such as anorexia, nausea, vomiting, diarrhoea, confusion, visual disturbance and arrhythmias.^3–7

• Poisoning Events

  A 60-year-old man developed corneal oedema and hazy vision 12 hours after rubbing the latex of the plant to his left eye inadvertently. He recovered fully 2 days after supportive treatment.³

CLINICAL MANAGEMENT

Supportive treatment. Multiple-dose activated charcoal therapy has been used for gastrointestinal decontamination in cardiac glycoside poisoning, and digoxin-specific antibody has been used as an antidote.^10,11

IDENTIFICATION FEATURES

Perennial herbs, up to 1 m tall, with white latex. Stems pale grey, puberulent to glabrous. Leaves opposite, lateral veins prominent; leaf blades 6–15 × 1–4 cm, base decurrent to petiole. Cymes 10–20-flowered; corolla purple or red, 7–9 mm long; corona hooded, lobes yellow or orange; pollinia pendulous. Follicles 5–10 × 1–1.5 cm. Seeds 6–7 × 3 mm, with coma.¹²

MEDICINAL USES

Whole plant used in TCM: relieve inflammation, clear heat and remove toxin, activate blood and stanch bleeding, resolve swelling and relieve pain. Recommended dose: 6–9 g.^4,13

LABORATORY ANALYSIS

Uscharin can be detected by LC-MS/MS.¹⁴