Beta-blockers are medications that are mainly used to treat various heart conditions, usually by decreasing the heart’s activity. These agents are often prescribed for the treatment of angina, heart failure, atrial fibrillation, and heart attack. Beta-blocker therapy can also benefit patients with anxiety, overactive thyroid (thyrotoxicosis), glaucoma and migraine.
The two main beta receptors that are targeted by beta blocker therapy are the beta 1 receptor and the beta 2 receptor. A large number of beta 1 receptors are present on the heart and kidney cells, while the beta 2 receptor is the predominant regulator of vascular and nonvascular smooth muscles.
Some beta blockers are selective and specifically target the beta 1 receptor. These are called cardioselective agents. Nonselective beta blockers are those that bind to both types of receptors.
Examples of the beta blocker drugs that are currently available include:
Non selective agents
Agents that are highly selective for the beta 2 receptor include butaxamine and several other therapies currently in development. However, there are no known clinical applications for these drugs and they are currently used only for experimental purposes.
Beta blockers that are fat soluble are excreted by the liver and include labetalol, metoprolol, pindolol and propranolol. Those that are water soluble such as atenolol, celiprolol, nadolol, sotalol are cleared by the kidney.
Specific beta blocker treatments
Some examples of the specific conditions certain beta blockers are used for include:
- Cardiac arrhythmia – Esmolol, landilol, sotalol.
- Congestive heart failure – metoprolol, bisoprolol, carvedilol, nebivolol.
- After heart attack – atenolol, metoprolol, propranolol.
- Glaucoma – betaxolol, carteolol, levobunolol, metipranolol, timolol.
- Migraine prevention – timolol, propranolol.