Organophosphates (Malathion) Flashcards
In commercial products, malathion is usually
dissolved in hydrocarbon solvents such as toluene or xylene, which are flammable.
Malathion has what kind of odor?
Garlic. which does not provide adequate warning of hazardous concentrations.
Describe the MOT of Malathion
Inhibition of the enzyme acetylcholinesterase (AChE) found in synaptic junctions, leading to accumulation of excessive acetylcholine
What is aging?
Permanent inhibition of acetylcholinesterase through covalent binding by the OP to the enzyme.
Highly lipophilic organophosphates such as disulfoton or fenthion are stored where and what is the consequence of that?
Stored in fat tissue, and this may lead to persistent toxicity lasting several days after exposure.
What is the LD50 of malathion?
1000mg/kg
Delayed onset of malathion may result from?
dermal exposures or indirect agents such as malathion and fenthion that require metabolism to the active form.
Wha are the clinical presentation of malathion?
agitation. seizures, coma
Chemical pneumonitis may occur if
a product containing a hydrocarbon solvent is aspirated into the lungs.
What are some muscarinic effects of malathion
Cardiovascular- Bradycardia, Hypotension
Respiratory- Respiratory distress, cough
Gastrointestinal- n/v
Ocular- miosis, blurred vision
There are 5 emergency and supportive measures for treating malathion. Describe them
- Maintain an open airway and assist ventilation if necessary.
- Pay careful attention to respiratory muscle weakness because sudden respiratory arrest may occur. This is often preceded by increasing weakness of neck flexion muscles.
- Treat hydrocarbon pneumonitis, seizures (with benzos), and coma if they occur.
- Observe asymptomatic patients for at least 8–12 hours to rule out delayed-onset symptoms
- Rescuers and health-care providers must take measures to prevent direct contact with the skin or clothing of contaminated victims, because secondary contamination and serious illness may result,
Describe the use of atropine as an antidote for malathion. Give its dose, indication, contraindication
Atropine will reverse muscarinic but not nicotinic effects.
0.5–2 mg IV initially, then double the dose every 5 minutes until signs of atropinization are present (decreased secretions and wheezing, increased heart rate).
The most clinically important indication for continued atropine administration is persistent wheezing or bronchorrhea.
Tachycardia is not a contraindication to more atropine.
Describe the use of pralidoxime as an antidote for malathion. Give its dose, indication, contraindication
Acts to regenerate the enzyme activity at all affected sites prior to aging.
1–2 g initial bolus dose IV over 5–10 minutes, followed by a continuous infusion.
Should be given immediately to reverse muscular weakness and fasciculations. . It is most effective if started early, before irreversible phosphorylation of the enzyme
Describe the decontamination of malathion (3 points)
- Rescuers should wear chemical-protective clothing and gloves when handling a grossly contaminated victim, clothing removal and victim decontamination should be carried out outdoors or in a room with high-flow ventilation.
- Skin- Remove all contaminated clothing and wash exposed areas with soap and water, including the hair and under the nails. Irrigate exposed eyes with copious tepid water or saline.
- Ingestion- Administer activated charcoal orally if conditions are appropriate.
Gastric lavage may be appropriate soon after moderate to large ingestions, but because of the possibility of seizures or rapidly changing mental status, lavage should be done only after intubation.
What enhanced elimination processes are used in malathion?
None due to the large VD of OP
