Clinpharm SGD Organophosphayte Poisoning

CLINICAL PHARMACOLOGY
SGD CASE 5: ORGANOPHOSPHATE POISONING

LECTURE NOTES
CLINICAL PHARMACOLOGY SGD5: ORGANOPHOSPHATE POISONING
Case 1 (Groups 1, 3, 5, 7, & 9)
A 20-year old suicidal female was brought by relatives at the Emergency Room after drinking 2 sips of 50% malathion about 3 hours
earlier. The patient was awake but confused and extremely diaphoretic. She had the odor of hydrocarbons, although there was no
evidence that the liquid had spilled onto his clothes. Her initial vital signs at the ER were: BP = 90/60 mmHg, pulse = 50 beats/min,
respiratory rate = 22 breaths/min, temp = 36.5C and oxygen saturation = 95% on room air. Physical examination demonstrated
pinpoint pupils, coarse crackles in all lung fields, and copious vomiting and diarrhea. The patient was drooling between episodes of
vomiting.
The patient was completely undressed and his skin thoroughly washed with soap and water. Oxygen was administered by face mask,
an intravenous line was inserted, and normal saline was infused.
Hematologic studies were normal except for a WBC of 19,000/mm3. Her other laboratory studies were remarkable for a glucose of 195
mg/dL, potassium of 3.2 mEq/L and serum bicarbonate of 18 mEq/L. Initial chest radiograph showed bilateral pulmonary edema.
Cholinesterase measurements sent initially showed virtually no detectable red blood cell activity.
Malathion pesticides for orchids or in farms

Non-accidental suicidal patient who ingested 2 sips of malathion
Amount ingested by the significant so it has more severe signs and symptoms severe toxicity
Aside from muscarinic effects (DUMBBELS), you also have nicotinic effects which are affecting your skeletal muscles
already
o DUMBBELS: Diarrhea, Urination, Miosis & Muscle Weakness, Bronchospasms, Bradycardia, Excitation / Emesis,
Lacrimation, Salivation / Seizures PARASYMPATHETIC (CHOLINERGIC - MUSCARINIC)
Respiratory symptoms pulmonary edema
Central nervous effect of confusion
Lab results: WBC of 19,000/mm3, hyperglycemia, hypokalemia, cholinesterase level undetectable (most important; almost
inhibited all enzymes)
3 hours exposure you already have severe manifestations
Psychiatric patient ask for previous attempts
Antidote: if pralidoxime is available, you can give both the atropine and pralidoxime (Protopam)
Give diazepam for nicotinic effects and phenytoin for the conversion of the more toxic metabolite malathion preventing it to
become malaoxone which is the more toxic compound
Give packed RBC to completely substitute the damaged cholinesterase enzymes
Give 2 mg Atropine every 5 to 15 minutes and monitor closely until full atropinization
Refer to psychiatrist for management of the cause
Case 2 (Groups 2, 4, 6, 8, & 10)

A 40 year old carpenter accidentally ingested a gulp of chlorpyrifos (anti-termite) mistaken for a drink contained in a softdrink bottle
inside a house they were building. He started vomiting several times with diarrhea. He was then brought to the ER by his co-workers.
He was awake but weak-looking and slightly diaphoretic. He smelled of kerosene. His vital signs showed BP = 120/80, PR=60/min, RR
= 20/min and Temp = 36.5C. His pupils measured 1-2mm EBRTL. The rest of the physical examination was normal except for
occasional crackles on the right lung field.
Initial laboratory examinations showed normal CBC and low potassium, ABG showed metabolic acidosis with pH of 7.2 and bicarbonate
at 20 mEq/L. Chest radiograph revealed pneumonitis. RBC Cholinesterase was 0.6 pH (20% depression).
Chlorpyrifos anti-termite
Chlorpyrifos is more toxic than malathion
Chlorpyrifos accidental ingestion; mild present cholinergic symptoms (Diarrhea, Urination, Miosis/pinpoint pupils,
Bronchoconstriction, Bradycardia, Emesis, Lacrimation, Salivation/Sweating)
CLINICAL PHARMACOLOGY
SGD CASE 5: ORGANOPHOSPHATE POISONING
LECTURE NOTES
Mild symptoms muscarinic effect

Accidental the carpenter ingested the chlorpyrifos
Mild toxicity
Lab results: metabolic acidosis, RBC cholinesterase 20% depressed (slightly inhibited so it falls under mild)
Lots of exposure to pesticides due to occupation
Antidote: atropine; no need to give pralidoxime
Supportive management: check the electrolytes, correct the acidosis
Advise the carpenter to prevent somehow further exposure
Atropine given until the symptoms subside or normalize, you can discharge the patient. But you have to give atropine as a
home medication also for 2 to 3 months because the half-life of RBCs is 120 days and youre trying to recuperate the life of
your RBCs; an ampule dissolved in a half glass of water given 3 times a day for 2-3 months until RBC cholinesterase levels
normalize
Atropine 1mg IV every 5-15 minutes, monitor closely until full atropinization (tachycardia HR >100bpm, dry mouth difficulty
swallowing, dilated pupils mydriasis, bowel sounds hypoactive)
Things you need to know regarding the exposure: timing, amount ingested (even an estimate; 5 to 10 ml for children, 60 to
70 ml for males, 45 ml for females = 1 gulp; amount left in the bottle or spillage), occupation (chronic exposure), any
medications, co-ingestion or maintenance drugs (a lot of drug interactions), chronic condition (those with renal impairment is
more prone to toxicity compared to normal individuals), pregnancy test
Severity will determine the management for the patient
What to do with a poison patient:
o Stabilize Airway, Breathing, Circulation
o Decontaminate limit the absorption of the poison (skin decontamination if the patient vomited bathe the patient with
alkaline soap, gastric lavage insert an NGT; activated charcoal, cathartics/sodium sulfate activated charcoal can be
excreted, enhance excretion)
o Give the antidote atropine (physiologic) and pralidoxime (pharmacologic; not available locally); for mild symptoms,
no need to give pralidoxime
Certain chemical warfare are organophosphates SARIN
Toxic effects of atropine allergic reactions, tachycardia, cardiac arrhythmias, confusion, anti-cholinergic toxidrome
o Hot as a hare
: Increase temp
o Blind as a bat
: Mydriasis
o Dry as bone
: Dry mouth, dry eyes, decrease sweat
o Red as beet
: Flushing
o Mad as a hatter : Delirium

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CLINICAL PHARMACOLOGY

SGD CASE 5: ORGANOPHOSPHATE POISONING

Malathion pesticides for orchids or in farms

Case 2 (Groups 2, 4, 6, 8, & 10)

Mild symptoms muscarinic effect

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