Organophosphorus compounds available in Nepal.& clinical features of OP poisoning.

1. ORGANOPHOSPHORUS
COMPOUNDS & CLINICAL
FEATURES
Presenter :Dr.Milan Bhusal

2. HISTORY
 First synthesized in early 1800 by Lassaigne
 Lange and Schrader investigated the use as insecticides
 German Military prevented the use; developed arsenal for chemical
warfare
 In 1941, re-introduced worldwide for pesticide use
 Used in various terrorist attacks and regional wars
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3. OP COMPOUNDS
 Dichlorvos
 Fenthion
 Malathion
 Ethion
 Diazinon
 Parathion
 Chlorpyrifos
DIMETHYL COMPOUNDS DIETHYL COMPOUNDS
NERVE AGENTS
G agents- Sarin, Tabun, Soman
V agents- VX, VE
INSECTICIDES

5.  Inhibit esterase enzymes
Acetylcholinesterase in
synapses and on red cell
membranes &
Butyrylcholinesterase in plasma
Accumulation of ACh and
overstimulation of ACh
receptors in synapses of ANS,
CNS and NMJ
 Recovery
 Aging
MECHANISM OF ACTION

6. Common OP compounds available in
Nepal

7. National poison information centre:
9851038490

9. Clinical features:
 IV/IM within 30 min.
 Oral or respiratory exposures - signs or symptoms within
three hours.
 Symptoms of toxicity from dermal absorption -
delayed 12 hours.

10. INHALATION
 Cough
 Difficulty in breathing
 Bronchitis
 Pneumonia
EYE CONTACT
 Irritation
 Pain
 Lacrimation
 Miosis
 Blurring vision
 Photophobia

11. SIGNS AND SYMPTOMS
 MUSCARINIC EFFECTS
 NICOTINIC EFFECTS
 CNS EFFECTS
 NEUROPSYCHIATRIC EFFECTS

12. MUSCARINIC:
Cardiovascular : Bradycardia, hypotension
Respiratory : Rhinorrhea, bronchorrhea, bronchospasm,
cough, severe respiratory distress
Gastrointestinal : Hypersalivation, nausea and vomiting,
abdominal pain, diarrhea, fecal incontinence

13. Genitourinary: Incontinence
Ocular: Blurred vision, miosis
Glands : Increased lacrimation, diaphoresis

14. CLINICAL PRESENTATION
MUSCARINIC: SLUDGE
S-Salivation
L-Lacrimation
U-Urination
D-Diarrhoea
G-GI upset
E-Emesis
NICOTINIC: MATCH
M-Muscle weakness and
fasciculation
A-Adrenal medulla activity ↑
T-Tachycardia
C-Cramping of skeletal
muscle
H-Hypertension
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15. CNS EFFECTS @C.E.A.S.T.A.R.
 Anxiety
 Emotional liability
 Restlessness
 Confusion
 Ataxia
 Tremors
 Seizures and coma

16. Neuropsychiatric effects
 Chronic
 Headache, blurred vision, muscle weakness,
depression, memory and concentration problem
 The mechanism is not proven

17. NEUROLOGICAL MANIFESTATIONS:
 Type I paralysis or Acute paralysis.
 Type II paralysis or Intermediate syndrome.
 Type III paralysis or Organophosphate- induced delayed
polyneuropathy(OPIDP)

18. Type 1 paralysis or Acute paralysis
 Muscles fasculations ,
 Muscles cramps.
 Twitching and weakness
 Respiratory muscles weakness and paralysis.
 CNS depression.
 Respiratory arrest.

19. TYPE II (INTERMEDIATE SYNDROME):
 Develops after 24-96 hours ; persists 4-18 days
 Respiratory distress, weakness of proximal muscles, neck and
trunk, with relative sparing of distal muscles
 Doesn’t respond to oximes or atropine, needs assisted ventilation
 Recovery in 5-18 days

20. IMS AND OPIDP
IMS
 Time of onset 1-4 days
 Proximal limb muscle weakness
 Neck muscle +
 Respiratory muscles +
 Recovery time 4-18 days
 Agents: Fenthion, Dimethoate,
Monocrotophos
OPIDP
 Time of onset 2-3 weeks
 Distal limb muscle weakness
 Neck muscle -
 Respiratory muscles -
 Recovery incomplete
 Agents: Methamedophos,
Trichlorfon, Leptophos
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21. TYPE III PARALYSIS:
 Delayed polyneuropathy
 Occurs 2-3 weeks after exposure to large doses of certain
organophosphates, last up to 12 months
 Damage to the afferent fibres and associated inhibition of
neuropathy target esterase
 Distal muscle weakness/paralysis/paresthesia
with sparing of the neck muscles, cranial nerves and proximal
muscles
 Recovery incomplete