- Timolol, though used as an eye drop for glaucoma, does have some systemic absorption and effects and can cause bradycardia and bronchospasm.
- *Molecular medicine pearl – Why is glucagon the treatment for beta blocker overdose, you might ask? Remember from med school that beta receptors are coupled to G-proteins, which activate cAMP formation from ATP – this process is inhibited beta blockers. Glucagon activates adenylate cyclase at a different site than beta receptors, which causes an increase in cAMP. The cAMP elevation the increases the intracellular calcium pool for release during depolarization to increase contractility.
- Because of this pathophys, calcium can also be a helpful adjunct in beta blocker toxicity
- Tachyphylaxis will develop to glucagon, so it cannot be use for prolonged treatment
- If possible pre-treat with anti-emetics before giving glucagon, as it causes severe nausea and vomiting
- Rivastigmine is an acetylcholinesterase inhibitor used to treat moderate Alzheimer’s dementia and nausea and vomiting are well-known side effects. It is known to increase vagal tone and can provoke bradycardia and heart block even in patients with no history of conduction disease.