Aconitine (sometimes known as the Queen of Poisons) is a highly poisonous alkaloid derived from various aconite species.
It is a neurotoxin that opens TTX-sensitive Na+ channels in the heart and other tissues, and is used for creating models of cardiac arrhythmia. Aconitine was previously used as an antipyretic and analgesic, and still has some limited application in herbal medicine although the narrow therapeutic index makes calculating appropriate dosage difficult.
Aconitine has the chemical formula C34H47NO11, and is soluble in chloroform or benzene, slightly in alcohol or ether, and only very slightly in water.
The Merck Index gives LD50s for mice: 0.166 mg/kg (intravenously); 0.328 mg/kg intraperitoneally (injected into the body cavity); approx. 1 mg/kg orally (ingested). In rats, the oral LD50 is given as 5.97 mg/kg. Oral doses as low as 1.5–6 mg aconitine were reported to be lethal in humans.
It is quickly absorbed via mucous membranes, but also via skin. Respiratory paralysis, in very high doses also cardiac arrest, leads to death. A few minutes after ingestion paresthesia starts, which includes tingling in the oral region. This extends to the whole body, starting from the extremities. Anesthesia, sweating and cooling of the body, nausea and vomiting and other similar symptoms follow. Sometimes there is strong pain, accompanied by cramps, or diarrhea. There is no antidote, so only the symptoms can be treated, traditionally with compounds such as atropine, strychnine or barakol, although it is unclear whether any of these are effective. Some other toxins such as tetrodotoxin that bind to the same target site but have opposite effects can reduce the effects of aconitine, but are so toxic themselves that death may result nonetheless. The anti-dysrhythmic drug lidocaine, which is clinically used for treating unusual cardiac rhythms, also blocks these sodium channels and there is a single report of a successful treatment of accidental aconitine poisoning using this drug. Serum or urine concentrations of the chemical may be measured to confirm diagnosis in hospitalized poisoning victims, while postmortem blood levels have been reported in at least 5 fatal cases
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