Beta-Blockers

Question 1

Beta blockers have generally mild toxicity except for which 2 beta blockers? (that are highly toxic)

Answer 1

Sotalol
Propanolol

They are both one-pill kill in paediatrics

Question 2

Why is propanolol more toxic than other Beta-blockers in overdose?

Answer 2

Sodium channel blockade
High lipid solubility hence CNS penetration

Can cause seizures and ventricular dysrhythmias

Question 3

Why is sotalol more toxic than other Beta-blockers in overdose?

Answer 3

Potassium channel blocker:
QT prolongation
Risk of TdP and ventricular dysrhytmia

Question 4

What are the features of b-blocker OD?

Answer 4

Bradycardia +/- hypotension
1-3 heart blocks
Seizures
Prolonged QTc -> TdP with sotalol
QRS widening -> VT/VF with propanolol

Question 5

What predicts ventricular dysrhythmia and seizures in propanolol OD?

Answer 5

Amount of QRS widening

Question 6

What is the specific treatment for propanolol OD?

Answer 6

Sodium bicarbonate 1-2mmol/Kg PRN 1-2mins until perfusing rhythm restored/QRS reduced
Intubation with hyperventilation (aim pH 7.5-7.55) particularly in siezures

Question 7

What treatment is no longer recommended?

Answer 7

Glucagon

Offers no advantage over ino/chronotropes