Dipyridyl Herbicides (paraquat/diquat) Flashcards Preview

Toxicology Fall17 > Dipyridyl Herbicides (paraquat/diquat) > Flashcards

Flashcards in Dipyridyl Herbicides (paraquat/diquat) Deck (25)
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1
Q

Is paraquat RUP or GUP? Is diquat RUP or GUP?

A

Paraquat = restricted use pesticide –> more toxic

Diquat = general use pesticide –> less toxic

2
Q

If paraquat is sprayed at 0.5 lb/acre for agricultural use, what is the mg/kg (body weight) toxicity?

A

3.5 mg/kg body weight

1lb/acre = 7 mg/kg body weight

3
Q

What are common sources of Dipyridyl herbicide poisonings?

A

Ingestion of concentrates

Malicious poisoning

4
Q

Which herbicide is better absorbed, paraquat or diquat?

A

Paraquat

Diquat is not very lipid soluble - poor absorption - less toxic

5
Q

What pH environments will destroy paraquat/diquat?

A

alkaline pH

these are stable in neutral or acidic environments

6
Q

What does paraquat bind strongly to in nature? How can this affect treatment?

A

Binds strongly to soil - could potentially be used as an adsorbent - but activated charcoal is even more effective

7
Q

T/F: Paraquat is caustic to mucus membranes

A

TRUE

8
Q

What percentage of paraquat will be absorbed in the GIT, why?

A

only 5-10% bc it is not very lipid soluble

9
Q

What animals are susceptible to paraquat poisoning? What is the toxic dose, and how is it categorized?

A

All animals are susceptible (cats, dogs, pigs, sheep, humans)

LD50 = 25 - 75 mg/kg

~ highly toxic (1-50 mg/kg)

10
Q

What deficiencies may increase the toxicity of paraquat? Why?

A

animals that are deficient in selenium & vitamin E, and glutathione

These are antioxidants- so without them or decreased amount can lead increase tissue damage

11
Q

What treatment can potentially increase tissue damage due to paraquat toxicosis?

A

Oxygen therapy

BUT - if the patient is in critical need, you should use it (just know it could increase tissue damage)

12
Q

Daily oral exposure to ___ppm paraquat causes chronic toxicity and death in dogs

A

170 ppm

13
Q

T/F: Paraquat is absorbed well by the GIT

A

FALSE

only small amounts are absorbed via the GIT and skin

14
Q

What is the distribution of paraquat in the body?

A

distributed all over the body but achieves the highest concentration in the lungs

15
Q

How is paraquat excreted?

A

Mainly unchanged in the urine within 24 hours (minimal metabolism)

16
Q

What is the MOA of paraquat?

A

tissue damage all over the body and severe damage in the lungs

production of free radicals that will cause oxidative cell membrane damage, degeneration, and necrosis

17
Q

What clinical signs will be noted with acute paraquat poisoning?

A

EARLY (first 24hr): usually limited to GI signs: vomiting, anorexia, depression (may resolve before resp. signs begin)

DELAYED (2-7days): this is the usual time frame of death for patients - respiratory signs: tachypnea, dyspnea, harsh resp. sounds, cyanosis, reduced pulmonary compliance

***sometimes signs aren’t seen until 3 days after exposure

18
Q

What clinical signs will be seen in a patient who survives paraquat toxicosis?

A

(subacute or chronic toxicosis: after 7 days up to 3 weeks)

Respiratory signs associated with progressive pulmonary fibrosis

patients will survive if not each lung lobe was affected or if they were not severely affected

19
Q

What lesions are associated with paraquat poisoning?

A

Pulmonary edema, congestion, hemorrhage, fibrosis, and failure of the lung to collapse
Lingual ulcers
Liver, Kidney, Spleen - enlarged/congested

“hepatosization” of the lung - grossly resembles the liver

20
Q

What are the chances of a positive chemical analysis on a urine sample that was collected 48 hours after paraquat ingestion?

A

slim to none

Urine samples may be negative after 48 hours from exposure

so by the time you see clinical signs and take samples - they likely will test negative

21
Q

What diagnostics could prove helpful in confirming lung lesions in the live patient suspected of ingesting paraquat?

A

Radiographs

22
Q

How is a paraquat poisoning diagnosis made?

A

History + clinical signs (GI in the first 24hr + Resp), Lesions, and laboratory diagnostics

23
Q

What would be differential diagnoses for paraquat poisoning?

A

Pneumonia
Inhalant toxicants like nitrous oxide and ammonia
Some rodenticides

24
Q

How are patients with paraquat poisoning treated?

A

Emetics (only before severe GI damage)
ACTIVATED CHARCOAL
Bentonite or Fuller’s earth choice PO
Parafin oil cathartics (more gentle than saline)

IVF, Hemodialysis/peritoneal dialysis

Antioxidants (better for prevention) - orgotein, acetylcystein, ascorbic acid, niacin or riboflavin

25
Q

What is the prognosis of paraquat poisoning

A

Guarded or grave

*only chance is if treatment is started within 24 hours of exposure (which is unlikely since resp signs aren’t noted for at least 48 hours)