Strychnine is a toxin found in the seeds of Strychnos nux-vomica that acts as a spinal poison. It works by blocking inhibitory glycine receptors in the spinal cord, causing uncontrolled muscle contractions and convulsions. Symptoms of strychnine poisoning include painful muscle spasms, risus sardonicus facial contortions, and convulsions that can be triggered by slight stimuli. Death is usually caused by respiratory failure or hypoxia within 1-2 hours without treatment. Management involves supportive care and benzodiazepines to control seizures.

1. SPINAL POISONS
-DR.ALAGUPRAKASH S

2. EXAMPLES OF SPINAL POISONS
• Strychnos nux vomica
• Physostigmatis semina or calabar bean
• Physostigmine
• Gelsemium sempervirens or jasmine

3. STRYCHNINE
• Botanical name: strychnos nux vomica.
• Common name: kuchila, dog buttons.

4. PHYSICAL FEATURES
• FAMILY: Loganiaceae.
• Medium sized tree with short & thick trunk
with irregular branches.
• Native to Indian subcontinent.
• Oval dark green leaves,fruits are globular &
contain disk shaped seeds.

5. USES
• RODENTICIDE
• FOR KILLING STRAY DOGS
• AS FOLK MEDICINE
• ARROW POISON FOR HUNTING

6. SEEDS
• Round and disk shaped,concave on one side &
convex on other side.
• Ash grey in colour & covered with silky fibres.
• 2.5cm in diameter & 5mm in thickness.
• Pericarp of seed is tough.

7. TOXIC PARTS & PRINCIPLE
• All parts of the plant are poisonous in
nature(i.e.seed,fruit,leaves,root,stem,bark
etc.,)
• ACTIVE PRINCIPLE:
Seed(STRYCHNINE,BRUCINE)
Other parts of plant(BRUCINE(Toxic
principle),LOGANIN(Glycoside))

8. STRYCHNINE MECH.OF ACTION
• Antagonizes the inhibitory neurotransmitter
aminoacid GLYCINE at post synaptic receptors.
• Inhibitory glycine receptors - abundant in spinal
cord & brainstem where they are mainly involved
in regulation of motor function.
• When inhibitors are blocked,ongoing neuronal
excitability is increased & sensory stimuli produce
exagg. Reflex effects,producing powerful muscle
contraction.

9. • Glycine receptors in higher brain centers,such as
substantia nigra,neostriatum & hippocampus -
insenstive to strychnine - strychnine symptoms
are largely spinal in origin.
• Styrchnine – well absorbed from GI mucosa &
nasal mucosa but not through skin.
• Metabolized in liver
• In nonfatal human poisoning,strychnine
disappearance follows first order kinetics with
half life of 10-16 hours
• Excreted mainly by kidneys with traces in
bile,milk,saliva.

10. FATAL DOSE & FATAL PERIOD
• SEEDS – 1-2 CRUSHED SEEDS or 50-100mg of
STRYCHNINE.
• Fatal period: 1-2 hours.

11. CLINICAL FEATURES
• If seeds are swallowed uncrushed, the hard
pericarp resists digestion & seeds are passed
in feces without any poisonous symptoms.
• With crushed seeds,symptoms begin to
appear within 15-30 minutes.
• Bitter taste in mouth,sense of
uneasiness,restlessness,fear&anxiety
• Acute onset of myalgia & gen. body ache.

12. • Increased difficulty in breathing & swallowing
• Muscle twitching & spasm of muscles are
followed by convulsions.
• Convulsions lasts for 30 secs to 2 minutes &
are precip. by slightest stimuli, such as
sudden noise, a current of air,or gentle
touching of pt.
• Convulsions are first clonic but eventually
becomes tonic.
• Inbetween the convulsions, the muscles are
completely relaxed & it is an important diag.
feature

13. • Convulsions are more ,marked in antigravity
muscles & body arches in hyperextension
position & lie on heel & head–OPISTHOTONUS
• Sometimes the body may bend forward –
EMPROSTHOTONUS.
• If body bends sidewise(i.e.lateral bending) –
PLEUROSTHOTONUS.
• Contraction of muscles of face – widening of
angle of mouth with creases appearing around
eyelids – “RISUS SARDONICUS” aka
“SARDONIC SMILE”

15. • Difficulty in breathing during convulsions due
to contraction of chest muscles & diaphragm.
• Pt remains conscious & maintains clear
sensorium during & between convulsions
• May be frothing at mouth & pupils are dilated
• Prognosis is good if interval for app. Of
convulsions increases & period of convulsion
decreases. Prog is bad if reverse
occurs(i.e.interval decreases & duration last
longer)

16. COMPLICATIONS
• Hypoxia
• Hyperthermia
• Rhabdomyolysis
• Metabolic acidosis/lactic acidosis

17. CAUSE OF DEATH
• Medullary paralysis due to hypoxia
• Respiratory failure due to spasm of respiratory
muscles

18. DIFFERENTIAL DIAGNOSIS
• Tetanus
• Rabies
• Meningitis
• Cocaine intoxication
• Phenothiazine poisoning
• Phencyclidine
• Hysteria

19. STRYCHNINE TETANUS
History of poisoning History of injury
Sudden onset Gradual onset
Fever not usual Fever is usual
Lock jaw absent Lock jaw present
Muscles are relaxed inbetween
convulsions
Muscles are stiff and not fully
relaxed
FATAL PERIOD: 1-2 HOURS FATAL PERIOD: >24HOURS
Laboratory findings on chemical
analysis for strychnine are positive
No poison detected but bacteria
present on microbiological
investigation

20. MANAGEMENT
• Calm environment.
• Emesis is contraindicated as the procedure
may precipitate convulsions.
• Cautious gastric lavage may be carried out
after protecting airway.
• Activated charcoal should be administered
and is considered as effective.

21. Convulsion management
• Managed by lorazepam or diazepam. If
benzodiazepines are ineffective, then short
acting barbiturate can be administered .
• Intractable convulsions may need muscle
relaxants, such as pancuronium.
• Maintain hydration through intravenous
fluids.closely watch vitals & urine output.
• Periodically, monitor levels of serum
potassium,magnesium,&creatinine kinase.

22. AUTOPSY FINDINGS
• RIGOR MORTIS –appear & disappear early bcos of
convulsion
• POSTMORTEM CALORICITY – bcos of convulsion
• May be signs of asphyxia.
• May be froth at the mouth bcos of pulmonary
edema.
• Occasionally muscle may show hemorrhages or
evidence of rupture
• Spinal cord is congested. Microscopy shows
multiple H’ges in ant. & post. Horns with “RING
H’ges” around capillaries. Neurons may show
chromatolysis.

23. SAMPLES TO BE PRESERVED
• ROUTINE VISCERA
• BLOOD
• SPINAL CORD

24. MEDICOLEGAL IMPORTANCE
• Accidental poisoning - in children,may chew
the seed out of curiosity
• Accidental poisoning – in adults due to
consumption of folk/indigenous medicinal
preparation.
• Homicide – rare due to bitter taste & dramatic
appearance of symptoms
• Suicidal cases – few cases are reported
• Used to kill stray dogs or used as rodenticide

25. THANK YOU