Nux vomica / strychnine poisoning / spinal poison

1. Strychnine toxicity 1

2. Strychnine(Nux
Vomica)
(Spinal Poison)
By Dr. Muhammad Zeeshan
Dept. of Forensic Medicine ,
BMC, Bannu

3. Key points
 Introduction
 Mode of action
 Signs and symptoms
 Fetal and Lethal doses
 Diagnosis
 Differential diagnosis
 Treatment
 Postmortem Appearance
 Medicolegal Aspects
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4. Introduction
 Synonym : Kuchila
 Strychnine is one of the most deadly of known
poisons. Strychnine is an alkaloid obtained from the
seeds of strychnos nux vomica.
 The seeds are
 Hard and flat
 About 2 cms in diameter
 ½ cm in thickness slightly convex on one side and
concave on the other side.
 Ash-grey in color
 Covered with fine downy hair and have a shinning hard
pericarp (outer coat)
 Intesely bitter in taste.
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5. Introduction (ctd)
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6. Introduction (cont’d)
Active Principles:
1) Strychnine
2) Brucine
3) Loganin
4) The bark, wood and leaves of the plant contain
brucine but no strychnine.
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7. Introduction (cont’d)
 Strychnine was previously used as
1. Purgative
2. Appetite suppressant
3. Aphrodisiac
4. Constituent of nerve tonics.
Today, this potent alkaloid is mainly used as
a rodenticide, and for killing stray dogs (Nux
vomica seeds are therefore sometimes
referred as “dog buttons”)
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8. Mode of Action
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 Strychnine competitively antagonizes
inhibitory neurotransmitter glycine by
blocking its postsynaptic uptake by
brainstem and spinal cord receptors.
 Note: GABA is the neurotransmitter for
presynaptic inhibitory neurons and is not
affected by strychnine.

9. Mode of action (ctd)
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10. Signs and symptoms
 NuxVomica seeds swallowed as a whole are nonpoisonous on account
of the hard pericarp which cannot be dissolved by digestive juices.
When broken seeds are taken or the seeds chewed, there is an
intensely bitter taste in the mouth.Within 15 minutes to an hour,
symptoms of poisoning appear.
• The patient is anxious and restless
• Stiffness of muscles occurs before typical strychnine convulsions
occur.These convulsion are at first clonic (intermittent) and then
tonic (sustained) in nature.They affect simultaneously both the
flexors and extensors.
• Opisthotonos:
• The muscle become stiff and rigid so that there is hyperextension of the spine
and body arched forward, resting only on the back of head and heels.
• Sometimes the body curve is in the opposite direction
(Emprosthotonos or sideways Pleurosthotonos)
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11. Signs and symptoms (ctd)
◦Risus Sardonicus:
it refers to the grinning or grimacing expression
seen on the victim’s face due to spasm of facial
muscles. Respiration is affected by the muscle
spasms and cyanosis may ensue. Fixation of chest
serves to distinguish strychnine convulsions from
those of tetanus.
◦Blood stained froth may be seen at the mouth.The
mind remains clear till the end, the patient
experiencing extreme pain during the convulsions.
◦Death may occur from asphyxia from spasm of
respiratory muscles, rhabdomyolysis, hyperthermia,
myoglobinuria and renal failure.
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12. Signs and symptoms (ctd)
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13. Fatal Doses and Lethal Period
Fetal Doses:
 15 – 30 mg of strychnine, that is, the
alkaloid content of one seed of nux
vomica.
Lethal Periods:
 The usual fatal period is 1 – 2 hours
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14. Diagnosis
 Recovery of strychnine alkaloid from the
stomach contents, vomitus, liver, kidneys, or
urine should be considered diagnostic
 The symptoms and signs of strychnine
poisoning may in some respects resemble
tetanus, epilepsy and hysteria.
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15. Differential Diagnosis
1. Epilepsy is distinguished by the loss of
consciousness and clonus.
2. Hysteria is distinguished by the character
of the convulsions
3. Tetanus
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16. Differential Diagnosis (ctd)
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17. Treatment
 Treat the patient in a quiet, dark room with minimal
external stimuli.
 Neuromuscular paralysis may have to be induced with
succinylcholine (50 mg i.v. ) to facilitate endotracheal
intubation.
 Curare or pancuronium bromide can be used instead of
succinylcholine.
 Oxygen therapy.
 Convulsions can be controlled with diazepam (10mg i.v.) or
barbiturates (600 mg pentobarbital i.v. )
 Induction of emesis and stomach wash to be avoided as far
as possible, since they can provoke convulsions. However
decontamination may become necessary when there is
suspicion that a substantial amount of the poison is still
present in the stomach. Stomach was with tannic acid can
be done after convulsion have been controlled.
 Acidification of urine can significantly enhance the
excretion of strychnine.
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18. Postmortem Appearances
 No specific signs have been described.
 PM findings are those of asphyxia
 Rigor mortis sets early.
 Postmortem caloricity is sometimes encountered, i.e.
the body temperature shows a slight rise for a while
after death instead of the usual fall.
 The remains of the seeds may be found in the stomach.
 Strychnine resists putrefaction and can be detected in
viscera.
 In deaths from suspected strychnine poisoning, heart,
brain, and spinal cord should be preserved for analysis
in addition to usual viscera.
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19. Medicolegal Importance
 Most fatalities from strychnine poisoning are accidental.
Strychnine poisoning has occurred through mistakes in
prescriptions, or when the poison applied externally is
absorbed.
 Homicide with strychnine is rare on account of the intensely
bitter taste and the convulsions that follow rapidly after
ingestion, but has been recorded.
 Suicide with strychnine is rare because death is so painful.
Children have been poisoned by swallowing a number of tonic
or purgative pills containing strychnine.
 Nux vomica is used as a love-philter and an aphrodisiac. It has
caused poisoning from an overdose thus taken.
 Nux vomica seeds are used for destroying cattle (cattle
poisoning). Strychnine is used for killing stray dogs, as a
rodenticide, and sometimes as an arrow poison.
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20. Strychnine toxicity 20