Toxicology

Question 1

What abnormalities may be seen in a patient with paracetamol overdose?

Answer 1

Raised LFTs esp. AST, ALT
Elevated PT
Metabolic acidosis
Impaired kidney function

Question 2

Who is considered at high risk for liver damage in paracetamol overdose?

Answer 2

Hepatic enzyme-inducing drugs (e.g. phenytoin, rifampicin, carbamazepine)
Alcoholics
Malnutrition
AIDS

Question 3

What metabolic disturbance occurs in salicylate overdose?

Answer 3

Respiratory alkalosis (due to stimulation of respiratory centre in brain)

Metabolic acidosis (due to production of a variety of acids)

Question 4

What is the antidote for opiate overdose?

Answer 4

Naloxone

Question 5

What are the 2 major clinical complications from TCA overdose?

Answer 5

Seizures
Cardiac toxicity (--> hypotension, arrhythmias, cardiac arrest)

Question 6

What are 2 major signs on ECG indicating TCA overdose?

Answer 6

1. QRS broadening > 0.1s

2. Abnormally tall T wave in aVR

Question 7

What is the normal therapeutic range of digoxin?

Answer 7

0.8-2 nmol/L

Question 8

What is the characteristic ECG sign for digoxin toxicity?

Answer 8

Down-sloping ST segment depression (reverse tick)

Question 9

What electrolyte abnormalities increase risk of digoxin toxicity?

Answer 9

Hypokalemia
Hypomagnesemia
Hypercalcemia

Question 10

What is the therapeutic index of lithium?

Answer 10

0.4-1.5mmol/l

LEVELS ABOVE 2 MMOL/L = V. TOXIC

Question 11

What are the treatment options in lithium overdose?

Answer 11

1.5-2 : fluid resuscitation, supportive treatment

>2 : may require haemodialysis