Zhi Cao Wu

Aconitum kusnezoffii Reichb. (Ranunculaceae) is a perennial herb native to northeastern China, Korea, eastern Russia, and Mongolia, growing 70-150 cm tall with palmately divided leaves and showy dark purple, helmet-shaped flowers in terminal racemes. It bears a paired tuberous root system of a 'mother' and 'daughter' tuber. Zhi Cao Wu is the processed lateral (daughter) tuber, prepared by prolonged soaking, repeated boiling, and steaming to hydrolyze the highly toxic diester diterpenoid alkaloids (mesaconitine, hypaconitine, deoxyaconitine) into far less toxic monoester or amine forms. Raw Cao Wu is severely cardio- and neurotoxic and is not used internally. In traditional Chinese medicine, processed Zhi Cao Wu is acrid, bitter, hot, and toxic, entering the heart, liver, kidney, and spleen channels; it dispels wind-damp, warms the channels, and relieves severe pain, used for wind-damp painful obstruction, cold-pattern joint pain, traumatic injury, and severe abdominal cold pain. Strict dose limits and prolonged decoction are required.