Describe the important plant poisons of India.

Irritant Plant Poisons

Cardiac Plant Poisons

• Aconitum napellus and A. Ferox — monkshood, bish, vatsanabha, meetha zahar. The toxin is aconitine, which acts on voltage-gated sodium channels, holding them open
• Features — almost immediate tingling and numbness of the tongue, lips and mouth, spreading to the whole body; a sensation of ants crawling; salivation, vomiting and abdominal pain; then ventricular arrhythmias — ventricular tachycardia and fibrillation, which are what kill; with consciousness retained until near the end. Fatal dose about 1 to 2 mg of aconitine; fatal period 2 to 6 hours
• Aconite is called the "king OF poisons" in India, and has been described as an ideal homicidal poison: it is highly potent, acts quickly, produces symptoms that may be mistaken for a natural cardiac death, and is difficult to detect on routine analysis and rapidly destroyed by putrefaction. Treatment is supportive, with amiodarone or flecainide for the arrhythmia, and there is no antidote
• NERIUM ODORUM (white oleander, kaner) and cerbera thevetia (yellow oleander, pila kaner) — contain cardiac glycosides (oleandrin, thevetin) with a digoxin-like action. Yellow oleander seed is among the commonest suicidal plant poisons in South India and Sri Lanka. Features: vomiting, hyperkalaemia, and bradyarrhythmias and heart block. Treatment: digoxin-specific Fab fragments are effective, together with atropine, temporary pacing and management of the potassium
• Cerbera odollam — the "suicide tree" of Kerala, similarly a cardiac glycoside
• Nicotine and Digitalis — the same broad group

Spinal and Deliriant Plant Poisons

• strychnos nux-vomica — kuchila, containing strychnine. It blocks glycine, the inhibitory transmitter of the spinal cord, so that every stimulus produces an exaggerated reflex response. Features: violent generalised convulsions with opisthotonos, risus sardonicus from spasm of the facial muscles, and consciousness fully retained throughout — so the patient is aware and in agony. Convulsions are precipitated by the slightest stimulus — light, noise, touch — with complete relaxation between them, unlike tetanus in which the rigidity persists. Death from exhaustion or asphyxia during a spasm. Treatment: a dark, quiet room with minimal handling, diazepam, and paralysis with ventilation in severe cases
• Distinguishing strychnine from tetanus — strychnine has a rapid onset in minutes, complete relaxation between spasms, and no trismus at the outset; tetanus develops over days, begins with trismus, and the rigidity persists between spasms
• cannabis SATIVA — bhang (leaves and seeds), ganja (flowering tops), and charas (resin, the most potent). Produces euphoria, distortion of time and space, conjunctival injection, tachycardia and increased appetite; and in large doses an acute toxic psychosis with hallucinations, historically described as "run AMOK". Regulated under the NDPS Act, though bhang occupies a partly tolerated position in Indian practice

Summary of the Indian Plant Poisons

Applied Aspects

• Ask about tingling of the tongue and mouth in an unexplained collapse with arrhythmia; it is the one early clue to aconite, which the laboratory may not find
• Give digoxin Fab in oleander poisoning; it is effective, and the bradyarrhythmia and hyperkalaemia otherwise respond poorly
• Recognise the fabricated marking-nut dermatitis — itchy, black-brown, streaky, with irregular margins and vesicles — and do not certify it as a bruise; fabrication to support a false charge is common
• Nurse strychnine in a dark quiet room and handle the patient as little as possible; every stimulus provokes a convulsion, and routine nursing observations may kill
• Distinguish strychnine from tetanus by the interval; complete relaxation between spasms means strychnine, persistent rigidity means tetanus
• Look for the sui or suiya puncture in suspected cattle poisoning, and preserve the skin and subcutaneous tissue around it for detection of abrin
• Preserve seeds, plant material and vomit for botanical identification; many of these poisons are identified from the fragments rather than chemically
• Toxalbumins inhibit ribosomal protein synthesis, which is the shared mechanism of abrin and ricin
• Whole abrus seeds often pass unharmed because of the hard coat, so toxicity requires chewing or the subcutaneous route
• Castor oil is harmless because ricin remains in the seedcake and is not expressed with the oil
• Aconitine holds sodium channels open, and the tingling of the tongue and mouth begins almost immediately
• Yellow oleander is a leading suicidal poison in South India and Sri Lanka, and digoxin Fab is effective against it
• Cerbera odollam is the suicide tree of Kerala, and acts by the same cardiac glycoside mechanism
• Charas is the most potent cannabis preparation, being the resin, with ganja the flowering tops and bhang the leaves
• Preserve seeds and plant fragments for botanical identification; many of these poisons are identified that way rather than chemically
• Marking nut dermatitis is itchy, streaky and black-brown, quite unlike a bruise, and is used to fabricate an injury
• Aconite may be mistaken for natural cardiac death, which with its poor detectability is why it is called an ideal homicidal poison
• Nurse strychnine in darkness and silence; every stimulus provokes a convulsion and routine observations may be fatal
• Abrus seeds are used to kill cattle for the hide, driven under the skin as a dried paste needle leaving a small puncture
• Ricin was used to assassinate Georgi Markov in 1978, and remains a recognised agent of deliberate poisoning
• Chilli powder thrown in the eyes to facilitate robbery is a common Indian offence and causes intense pain and temporary blindness
• Calotropis latex is vesicant and is used both as an abortifacient and as a cattle poison
• Send plant material to a botanist; identification of a seed or fragment is often more decisive than chemical analysis