Strophanthus divaricatus 羊角拗

Apocynaceae 夾竹桃科

Goat Horns, Divaricate Strophanthus¹

羊角扭、羊角藤、羊角藕²

POISONOUS PARTS

Whole plant, especially the seeds.^3,4

TOXICITY

Toxic Constituents
Cardiac glycosides such as divaricoside, divostroside, sinoside and strophanthins.^2,3
Mechanism
Cardiac glycosides inhibit Na⁺/K⁺-ATPase of the myocardium, increase its excitability and may lead to arrhythmias.^5–7
Poisoning Features
Digitalis-like toxicity such as nausea, vomiting, abdominal pain, dizziness, headache, hypotension, arrhythmias, hyperkalaemia, agitation, confusion, convulsion, coma and even death.³
Poisoning Events
A cluster of 3 poisoning cases has been reported in China. 3 children played with the flowers and leaves of S. divaricatus. They developed toxicity after they ate with their hands which had been contaminated by the plant. They recovered completely.⁸

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.^9,10

IDENTIFICATION FEATURES

Lianas or sarmentose shrubs, up to 4.5 m tall, with clear or yellowish latex. Branches dark grey, densely lenticellate, branchlets reddish brown. Leaves opposite; leaf blades 3–10 × 1.5–5 cm. Cymes 3–15‑flowered. Corolla yellow, lobes with red basal spots adaxially, up to 10 cm long, lobes apex caudate to filiform. Follicles 9–15 × 2–3.5 cm, woody, divergent at an angle 180–250°. Seeds 1.3–2 cm long, fusiform, with coma.¹¹

MEDICINAL USES

Highly toxic; use with caution. Uses in TCM—roots, or branches and leaves: dispel wind-dampness, unblock the meridian and collateral vessels, expel toxin and heal furuncles, kill parasites, relieve itching, relieve pain; seeds: dispel wind and unblock the collaterals, remove toxin and kill parasites. For external use only.^2,12,13

CASES IN TRL

In 2015, a middle-aged man collected a fruit of S. divaricatus from the countryside, soaked the skin of the fruit in wine and applied it topically to treat a skin condition. He presented with dizziness and bradycardia. He recovered completely. The serum digoxin immunoassay result was weakly positive.