Toxicology

Question 1

How to increase excretion of a weak acids (salicylates, phenobarbital). What would you use

Answer 1

Force diuresis and make urine alkaline.

IV dose of bicarb 1-2mEq/kg followed by intermittent bolus/ continuous drip to maintain urine pH at 7.5-8

Question 2

What is NAC (N-acetylcysteine)

Answer 2

Antidote for hepatotoxicity due to acetaminophen overdose. Also recently potential therapeutic agent for treatment of cancer, heart disease, HIV, heavy metal toxicity, and other diseases caused by free radical oxidant damage.

Question 3

Discuss ethanol kinetic aspects

Answer 3

Absorption: 20% stomach 80% intestine
Distribution: rapid (VD 0.6L/kg)
Elimination: 2-10% urinary and breathing unchanged
Metabolism (liver):
Cytosol: Alcohol dehydrogenase (10-20mg/dl/h)
MEOS - inducible (30-40mg/dl/h) in high consumption
It is A ZERO ORDER KINETIC

Question 4

Name some zero order kinetic elimination drugs

Answer 4

Ethanol, Phenytoin, Salicylates, Cisplatin, Fluoxetin, Omeprazol

Question 5

Discuss ethanol and byproducts effects

Answer 5

Ethanol = CNS depression
Acetaldehyde - vasodilation, nausea and vomiting
Acetic acid = metabolic acidosis

Question 6

What is flumazenil?

Answer 6

Benzodiazapine antagonist that can be used in confirmed overdose. Contraindicated in chronic benzo use, history of seizures, concomitant ingestion of tricyclic antidepressants. Will help to reverse the CNS depression.

Question 7

How to treat benzodiazepines overdose

Answer 7

Gastric lavage, activated charcoal, flumazenil. However, be aware that the benzo half life (15 to 100 hours half life in elderly) is longer than flumazenil (40 mins) so risk of relapse into unresponsiveness (total dose of max 1mg/hr) continuously given. So bolus and then infusion to help stop relapse.

Question 8

Typical symptoms of organophosphate poisoning

Answer 8

Muscarinic: DUMBELS
Diarrhea
Urination
Miosis
Bronchorrhea, bradycardia
Emesis
Lacrimation
Salivation, secretion
Nicotinic:
Also weakness, flaccid paresis

Question 9

Antidote for Organophosphate OP poisoning? Or carbamates (other carbamates include: aldicarb, methacarb)

Answer 9

Atropine - reverses MUSCARINIC which is critical for pulmonary effects (bronchospam/secretions) but does not have any nicotinic effects!! Has no effect on the skeletal muscle so still find fasciculation.
For this we use OXIMES such as
2-PAM - Pralidoxine chloride which are able to regenerate AchE.