April 17, 2024


  • December 12, 2009
  • 3 min read


-OP compounds are widely used as pesticides, for eradication of vectors.

Malathion,Fenthion,Methamidophos,Diazinon,Chlorpyrifos,Parathion are the common insecticides.

Organophosphorus Poisoning
Organophosphorus Poisoning


  • Acute cholinergic syndrome:- occur within minutes of exposure.
  • Pungent garlic like odour in breath, vomit and clothing; Muscarinic effects -miosis , bronchorrhoea, bronchospasm, salivation , lacrimation , abdominal pain , bradycardia
  • Nicotinic effects- Muscle fasciculation, hyper-reflexia, flaccid muscle weakness with reduced tendon reflexes
  • CNS effects- headache, dizziness, confusion, drowsiness, coma , fits , central respiratory depression
  • The Intermediate Syndrome- begins 48hrs after poisoning but may be delayed for 72-96 hrs. Follows resolution of the acute phase , in some instances occurs while symptoms of acute phase are still present.
  • Muscle weakness causing respiratory distress and failure; progression of muscle weakness from ocular muscles to the neck and proximal limbs to the respiratory muscles.

Organophosphate induced delayed polyneuropathy:-

Occurs 1-3 weeks after acute exposure due to degeneration of long myelinated nerve fibres. Cramping muscle pains in the legs , numbnesss and paraesthesiae in the distal upper and lower limbs, shuffling gait , wrist drop.

Muscle wasting and deformity, symmetrical flaccid weakness of distal limbs, tendon reflexes reduced or lost, absent ankle reflexes.


-Removal from site of exposure and of contaminated clothing and contact lenses.

-airway cleared and high flow oxygen administered.

-skin washed with soap and water and eyes irrigated.

-gastric lavage within an hour of ingestion by KMNO4 via nasogastric tube after establishing intravenous access and airway protection.

-Atropine : 1.8-3mg bolus immediately.

Atropine vial 1 ml conating 0.6 mg
Atropine vial 1 ml conating 0.6 mg

Double the dose every 5mins until atropinised- dilated pupil, clear lungs, dry tongue, normal heart rate and BP.

Heart rate maintain 110-120/min not<90.

Once patient is atropinised give 20-30% dose required for atropinisation as infusion/hr.

Eg: 15ml for atropinisation ( 1ml=0.6mg) then maintain at 20% dose of atropinisation at 1 hr i.e 3ml

Total dose = 3ml x 24 hr= 72ml

72ml/5 pint?15ml

In 1 pint put 15ml of atropine and as muscarinic effect decreases decrease dose i.e 8ml-6ml-4ml-2ml

-Oximes : Pralidoxime 1g bolus in 30 mins then infusion 0.5g/hr


Pralidoxime 1g in 100ml NS drip in 30 mins stat then TDS for 5 days.

Or , Obidoxime 0.25mg bolus then infusion 0.75g/24hrs.

Convulsions are controlled with I.V. Diazepam.

Monitoring of ECG, blood gases, temperature, urea and electrolytes , amylase and glucose is mandatory.

OP poisoning cases should be always kept under observation in Intensive Care Unit for 5-6 days.

– Dr. Mahesh Shrestha

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  • How can farmers prevent organophosphates poisoning during spraying of pesticides in their fields? What resources can farmers in context of Nepal utilize to protect themselves from the effect of OP?

    I’m a student of environment science, doing my project on the topic. Your reply will really be helpful to me?

  • atropine challange test ko barema lekheko bhaye ramro hunthyo

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