4

Question 1

Mechanism of action for Cyanide is?

Answer 1

• Binds to iron in the ferric state Fe³⁺
• Inactivates reduction/oxidation reaction Fe²⁺/Fe³⁺
• Hypoxia keeps iron in Fe³⁺
• Prevention of formation of ATP

Question 2

Sources and therapy of ethylene glycol intoxication?

Answer 2

Antifreeze (cars and radiators)

Therapy aim:
1. Decrease absorption
2. Increasing excretion of unmetabolized ethylene glycol
3. Preventing metabolism - 4methylpyrazole (4-MP) inactivates alcohol bicarbonate, i.v. or ethanol
4. Correcting the metabolic acidosis - administration of sodium bicarbonate, i.v.

Question 3

Classification of rodenticides?

Answer 3

Inorganic rodenticide
* Zinc phosphate
* Elemental phosphorus
* Thallium sulphate
* Oxide arsenite

Organic rodenticide
* Coumarin rodenticide - warfarin and superwarfarin
* Fluororacetates
* Alphanapthylthiourea (ANTU)
* Alphachloralosa
* Endrin
* Bromethaline
* Cholecalciferol
* Compounds of plant origin - Strychnine and sea onion

Also divided by:
-Accumulation
-Single dose

Question 4

Write down the most important chelating agents used in the therapy of heavy metals?

Answer 4

1. BAL - dimercaprol
2. CaEDTA - Calcium Ethylene Diamine Tetra Acetate

Question 5

Write down the typical clinical symptoms and post mortem picture in warfarin intoxication?

Answer 5

Symptoms
* Bleeding, internal and external
* Bleeding from the natural body openings
* Anaemia (Pale mucous membranes)
* Weak, fast pulse
* Subnormal body temperature
* Respiratory difficulty
* Death (5-7 days after poisoning)

Necropsy
* Presence of well developed hematomata in the soft tissues or large quantities of blood in the GIT may be expected
* Blood in the heart and vessels will be poorly clotted or not clotted

Question 6

Absorption and retention of copper in the body are influenced by?

Answer 6

• The amount of molybdenum and sulphate taken in at the same time
• This is due to the mutual relationship that exists between the metabolism of copper and that of molybdenum and sulphate

Question 7

Write down 2 groups of insecticides of which mechanism of action is inhibition of enzyme acetyl cholinesterase?

Answer 7

1. Organophosphates
2. Carbamates

Question 8

Write down the advantages of pyretroids?

Answer 8

• More effective at killing insects than pyrethrins
• Are used in low application concentrations
• In natural ecosystems they undergo quick degradation mainly by soil MO’s

Question 9

Write down 3 groups of symptoms in organophosphate intoxication?

Answer 9

1. Muscarinic effects
2. Nicotinic effects
3. CNS signs

Question 10

ANTU acts?

Answer 10

• After ingestion
• Compound is present in blood and increases the permeability of lung capillaries that causes pulmonary oedema
• Accumulation of serous transudate in the lung alveoli

Question 11

Mechanism of action of Zn₃P₂ in the stomach?

Answer 11

• In the acid environment of the stomach or in contact with water, hydrogen phosphide (PH₃) is released from zinc phosphide

Zn₃P₂ + 6HCl -> 2PH₃ + 3ZnCl₂

1. Zinc phosphide
2. Hydrochloric acid
3. Hydrogen phosphide
4. Zinc chloride