Toxicology

Question 1

How does Para cause liver damage

Answer 1

Toxic metabolites deplete Glutathione and other antioxidants in Liver then cause Oxidative Liver damage

Question 2

Abnormalities seen in Paracetamol

Answer 2

Elevated Liver enzymes (especially AST and ALT)

Elevated PT and INR - Impaired synthetic function in Liver

Elevated Urea and Creatinine - Hepatorenal syndrome & Para metabolite Renal damage

Metabolic acidosis (high anion gap) due to Liver failure

Question 3

Paracetamol antidote & what is used to determine need

Answer 3

N-acetylecysteine replenishes antioxidant stores (beware anaphylactic risk)

Graph of time Vs Plasma paracetamol concentration

Question 4

Who is high risk of Paracetamol OD

Answer 4

On Hepatic enzyme-inducing drugs (CRP - Carbamazepine, Rifampicin, Phenytoin)

Alcoholics

Malnutrition (e.g. Anorexia)

AIDS

Question 5

Salicylate poisoning effect

Answer 5

Metabolic Acidosis

Respiratory compensation can push patient into alkalosis (hyperventilation)

Question 6

Salycilate poisoning Tx

Answer 6

Activated charcoal if recent ingestion

Sodium Bicarbonate IV (for acidosis and also increases Urinary excretion of Salicylate)

Question 7

Opiate OD Signs

Answer 7

Slow resp rate
Decreased consciousness
Pin-point pupils

Question 8

Tricyclic antidepressant OD (e.g. Amitriptyline) complication

Answer 8

Cardiac toxicity (Hypotension, arrhythmia, arrest)

Seizures

Question 9

ECG changes in TCA OD

Answer 9

Widened QRS complex (over three small Squares - 120ms)

Tall T-waves in aVR

Question 10

ABG in TCA and Tx

Answer 10

Metabolic acidosis may occur

Tx with Sodium Bicarbonate

Question 11

Digoxin toxicity ECG

Answer 11

Down sloping ST segment

Virtually any type of arrhythmia

Question 12

E.g. of drugs with narrow therapeutic index

Answer 12

Digoxin

Theophyline

Lithium

Phenytoin

Abx (Gentamicin, Vancomycin)