Beta blockers

β1

Heart
Kidneys
- β1 blockade of the juxtaglomerular cells → ↓ renin release → ↓ angiotensin II conversion → ↓ H₂O resorption → ↓ BP

Tip

Beta-1 agonists can result in increased renin release → hypokalemia
Beta-2 agonists can increase the activity of the Na-K-ATPase pump → hypokalemia (transient)

Beta blocker overdose

Clinical features

Clinical features of CV drug poisoning: typically bradycardia, hypotension, and CNS depression
Other features
- Delirium
- Respiratory depression
- Seizures (typically seen with propranolol)
- Bronchospasm (rare)

Management

Hypotension: IV fluid bolus
Symptomatic bradycardia: atropine
High-dose glucagon therapy
- Glucagon activates adenylate cyclase, leading to increased intracellular cAMP during depolarization, which improves cardiac contractility and heart rate.