Organophosphate poisoning

Objectives Mode of toxicity Variability of toxicity Toxicokinetic Toxicodynamic Clinical picture Treatment & prevention

Organophosphate Poisoning

Herbicides and Fungicides Insecticide and pesticides Organophosphates and carbamates Herbicides and Fungicides Rodenticide

Mode of toxicity Accidental: After Eating contaminated food or insecticides used in gardens cause accidental poisoning in children. Transdermal : Lice control by special products (malathion). Occupational: exposure in farm workers during application. Suicidal: poisoning by (parathion). Homicidal poisoning: rare.

Variability of toxicity High toxic  agricultural insecticides  parathion Intermediate  animal insecticides Low toxic  household use  malathion Ex: Fatal oral dose: Parathion 0.05 g/ 70 kg Malathion 60 g/ 70 kg

Toxicokinetic Absorption Through skin, GIT, Resp. Distribution Most are water soluble , few lipid soluble Metabolism Some metabolites are more toxic (maloxone - paroxone) Excretion In urine

Toxicodynamic Acetylcholine Acetylcholine is the most important chemical transmitter at synaptic junctions Acetylcholine So inhibition of acetylcholinestrase increases Ach at nerve endings (OP’s effect). Acetylcholinestrase Acetic acid + choline Hydrolysis

Acetylcholine at synaptic junctions

Clinical Picture + Death Acute Cholinergic: Peripheral Muscarinic Peripheral Nicotinic Central Respiratory failure + Death Late complication: O.Ph. Induce intermediate or type 2 organophosphate syndrome and delayed neuropathy

D U M B E L S Muscarinic Effects D iarrhoea U rination M iosis B radycardia, Bronchorrhoea, Bronchospasm E mesis L acrimation S alivation

M A T C H Nicotinic Effects M uscle weakness and paralysis A drenal medulla activity increase T achycardia C ramps of skeletal muscles. H ypertension.

2C 2D SHM CNS effects C onfusion C oma D isorientation D epression : Respiratory & circulatory centers H eadache M alaise S eizures

Management Resuscitation Atropinisation of symptomatic patients The priorities in management are: Resuscitation Atropinisation of symptomatic patients Decontamination

1- Immediate supportive measures Patent airway + oxygenation Atropine until secretions dry Frequent suction Endotrachial intubation & mechanical ventilation in severe cases Cardiac monitoring

2- Decontamination Skin decontamination: - Remove clothes - Wash skin with water and soap then alcohol then soap and water. GIT decontamination: - Activated charcoal. - Emesis & gastric lavage are contraindicated

3- Antidotes Atropine : Initial atropine dose (IV or IM) 1-2mg (adult) 0.05mg/kg (children) Dose can repeated every 15-30 sec till Clear chest on auscultation or ATROPINISATION.. Pralidoxime (2-PAM chloride) before aging Dose 1-2g(adult) 25-50 mg/kg (children)

Prevention Protective clothes Using long nozzle during spraying Prevent eating during work Washing after work

Summary OP’s action Effects Treatment Block AChE, prolonged duration of ACh in synapse Effects Muscarinic, Nicotinic, CNS Respiratory failure and Death result from this Treatment ABC’s, Decontamination, Atropine