Organophosphates

Question 1

What are the uses for Organophosphates?

Answer 1

Animal and plant insecticides
insecticide synergists
antihelmintics
antiglaucoma 
Soil nematocides
fungicides
herbicides
rodenticides
insect repellants

Question 2

What are the sources for Organophosphates?

Answer 2

Contaminated feed or water
Empty pesticide containers used for feeding and watering animals
Dusting or spraying animals or animal premises
Overdosing

Question 3

What is the mechanism of Action of Organophosphates?

Answer 3

Irreversibly inactivates acetylcholinesterase

Question 4

What is the most common organophosphate?

Answer 4

Malathion

Question 5

How long do Organophosphates persist in the environment?

Answer 5

2-4 weeks

Question 6

What is “Storage Activation”?

Answer 6

If sealed and stored 1-2 years it is more toxic

Question 7

What is the solubility of Organophosphates?

Answer 7

Lipid soluble

Question 8

What is the difference between Technical grade and pure compounds?

Answer 8

Technical grades are more toxic

Question 9

What are the two types of Organophosphates?

Answer 9

Phosphates

Thiophosphates

Question 10

Phosphates

Answer 10

biologically active

direct effect on Acetylcholinesterase activity

Question 11

Thiphosphates

Answer 11

require hepatic activation

Desulfurated by liver enzymes

Question 12

What are thiophosphates transformed into?

Answer 12

-oxon metabolites

Question 13

Are Thiophosphates biologically active?

Answer 13

NO

Question 14

What is the solubility of Thiophosphates?

Answer 14

Lipid Soluble

Question 15

What is the major route of elimination of Thiophosphates?

Answer 15

paraoxonase

Question 16

What are the toxicokinetics of Organophosphates?

Answer 16

Lipophilic
Metabolized in the Liver
Lethal Synthesis of Thiophosphates in the Liver

Question 17

How are Organophosphates absorbed?

Answer 17

Dermally
Orally
Inhaled

Question 18

What can continued exposure of Organophosphates lead to?

Answer 18

Adaption to decreased acetylcholinesterase

Receptor down-regulation or decrease in acetylcholine receptor

Question 19

What are the 3 steps of Irreversible inhibition of cholinesterase

Answer 19

1. Muscarinic receptor over stimulation
2. Nicotinic receptor over stimulation
3. Nicotinic blockade

Question 20

High exposure to Organophosphates can lead to what?

Answer 20

respiratory failure
paralysis
death

Question 21

What are the Muscarinic clinical signs of Organophosphates?

Answer 21

Diarrhea
Urination 
Miosis
Bronchospasm
Emesis
Lacrimation 
Salivation 

“DUMBELS”

Question 22

What are the Nicotinic clinical signs of Organophosphates?

Answer 22

Fasciculations of muscles
Sweating
Hypertension
tachycardia

Question 23

What are the CNS clinical signs of Organophosphates?

Answer 23

Increased sensory and behavioral disturbances
incoordination
depressed motor function
respiratory depression

Question 24

What are usually the clinical signs that lead to death?

Answer 24

Respiratory failure from increased pulmonary secretions

Question 25

What are the delayed effects of Organophosphates?

Answer 25

10-14 days after exposure muscle weakness ataxia rear limb paralysis

Question 26

Organophosphate-induced intermediate syndrome

Answer 26

2-4 days after acute cholinergic effect NO muscarinic or muscle fasciculations Weakness of respiratory muscles and accessory muscles including neck muscles and of proximal limb muscles

Question 27

What kind of inhibition does Organophosphates cause?

Answer 27

Non-competitive inhibitiom

Question 28

What tissues do you detect Organophosphates in?

Answer 28

Stomach or rumen contents | analysis of the hair and skin

Question 29

What is a laboratory test for diagnosis of Organophosphates toxicosis?

Answer 29

Plasma Acetylcholinesterase activity level

Question 30

What is a clinical test for diagnosis of Organophosphates toxicosis?

Answer 30

Atropine Response Test

Question 31

What are the signs seen in an animal with the atropine test that is negative for Organophosphate toxicosis?

Answer 31

Dry skin and mucous membranes increased heart rate dilated pupils decreased bowel sounds

Question 32

How do you treat Organophosphates toxicosis?

Answer 32

Decontaminate: Emesis, Activated Charcoal, or Bathing the animal Supportive care Atropine Cholinesterase reactivators - "oximes"

Question 33

What drugs do you avoid with Organophosphate toxicosis?

Answer 33

phenothiazines aminoglycosides muscle relaxants opoids

Question 34

How do you treat Organophosphate induced delayed polyneuropathy?

Answer 34

Symptomatic therapy ONLY

Question 35

How do you treat Organophosphate induced intermediate syndrome?

Answer 35

Supportive care | 2-PAM chloride - "oximes"

Question 36

What is the mechanism of Action of 2-PAM chloride "oximes"?

Answer 36

binds to Organophosphate inactivated acetylcholinesterase to reverse Organophosphate binding

Question 37

What is the prognosis of Organophosphates?

Answer 37

Good if presented alive with no clinical signs Treatable, if presented with mild to moderate clinical signs If presented with multiple clinical signs, level of various treatments may depend on finances