What is Beta-Blocker Toxicity?
Beta-blockers are a type of medication that work against beta-adrenergic receptors, and are mainly used to treat high blood pressure, heart failure, fast heart rates, and chest pain from heart disease. In addition to these heart-related conditions, beta-blockers can also be used to manage anxiety, migraines, a certain type of eye disease called glaucoma, hand tremors, overactive thyroid, and various other health problems. Propranolol, one of the earliest beta-blockers, has been used in the United States since 1973.
The creation of beta-blockers has been a game-changer in treating heart issues, and has been proven to help patients with diseases affecting the blood supply to the heart by reducing the likelihood of further heart deterioration and improving their survival rate. This happens because beta-blockers lessen the effects of adrenaline-like substances on heart tissue. These medications are even recommended by the American College of Cardiology Foundation and American Heart Association Task Force to treat heart failure.
What Causes Beta-Blocker Toxicity?
The reasons behind beta-blocker overdose often have to do with factors like depression and other health issues that require beta-blocker treatment. According to one study, people who overdose on beta-blockers are more likely to be women, with an average age of 30. A large number of these individuals either accidentally ingested someone else’s medication or used beta-blockers for reasons not related to heart issues, such as migraines, shaking, or an overactive thyroid.
Risk Factors and Frequency for Beta-Blocker Toxicity
In 2015, the American Association of Poison Control Center (AAPCC) reported 10,577 cases of exposure to beta-blockers, which are a type of medication. Of these, roughly 10% (1022 cases) had moderate to major side effects. Most of the exposures (82% or 8706 cases) were accidental. Interestingly, there were 118 more instances of beta-blocker exposure in 2015 than in 2014, but fewer fatal cases (eight compared to 14). The beta-blocker that most often caused toxicity was propranolol.
Signs and Symptoms of Beta-Blocker Toxicity
When dealing with a medical situation, it’s important for medical providers to have a clear understanding of any other substances a patient might have taken at the same time, especially those known as anticholinergics and those that can harm the heart. For instance, taking calcium channel blockers together with certain substances can result in very low blood pressure and heart damage. Other medications that can have harmful effects on the heart include certain types of antidepressants and antipsychotic drugs, which can make the toxicity of a category of drugs called beta-blockers worse. It’s particularly crucial to consider this in patients with pre-existing heart disease since they have a higher chance of poor outcomes. Also, beta-blockers don’t all have the same duration of effect; their half-lives can vary from just a few minutes to multiple hours. This is why it’s essential to identify the specific beta-blocker involved.
Testing for Beta-Blocker Toxicity
Signs of slow heart rate (bradycardia) and low blood pressure (hypotension) can be one of the first indications of an overdose from beta-blockers, a type of medication used to reduce blood pressure and prevent heart attacks. Compared to overdosing from a similar type of medication called calcium channel blockers, those who overdose on beta-blockers might also experience low blood sugar (hypoglycemia) and confusion (altered mental status).
The symptoms from overdosing on beta blockers usually show up quite quickly, often within one to two hours. However, the danger of toxicity, or poisoning, can remain high for up to 20 hours if the patient has taken the beta blocker called sotalol. Sotalol has the additional risk of prolonging the QTc interval – a measurement of the time it takes for the heart to recover between beats – up to three or four days. This may require close monitoring in a healthcare setting.
Prolonged QTc may need to be corrected if possible, and the use of any other medication that could potentially increase the QTc interval should be stopped. Additionally, if any slow-release medications or beta blockers with a long-lasting effect were consumed, the patient may need longer-term monitoring.
Patients suspected of beta-blocker overdose should have their vital signs like heart rate and blood pressure constantly tracked. Moreover, it is advisable to perform regular electrocardiograms (EKGs) – a simple test that can check heart rhythms – to monitor the functioning of the heart.
Treatment Options for Beta-Blocker Toxicity
Beta-blockers are medications that can make you feel sluggish due to their ability to easily blend with fats, which is known in medical terms as ‘lipophilicity’. Therefore, maintaining a clear airway is important. This is done by placing a special type of tube (endotracheal tube) into your throat if you seem overly sleepy.
Sometimes a drug called atropine may be used before this tube is placed, especially in children. The reason is that touching the throat may cause the heart to slow down, which atropine helps to minimize. For those struggling to breathe due to bronchospasm – a condition where the muscles that line the airways tighten – oxygen and inhalers like albuterol, that help open up the airways, are used.
When a large quantity of the drug is taken and serious symptoms are seen, gastrointestinal decontamination may be needed. Gastrointestinal decontamination is essentially cleaning up your gut. Activated charcoal, a medication that helps limit the absorption of the beta-blocker, may be given if the symptoms are minor and the patient is seen more than an hour after taking the drug.
Regular irrigation of the bowel with a solution until the stool is clear is another approach used to remove any remaining beta-blockers in your system. Seizures that may occur due to certain types of beta-blockers are treated with drugs known as benzodiazepines.
If your doctor sees certain changes in your heart rhythm (QRS widening and prolongation of QTc interval), they might use sodium bicarbonate and magnesium sulfate respectively to treat these.
Glucagon, despite lacking concrete research validation, is often used in treating beta-blocker overdose. Glucagon, however, may cause vomiting, so anti-nausea drugs may be given before it is administered.
In cases where a patient’s blood pressure is dangerously low after overdosing on beta-blockers, the patient might be given calcium salts. If previous treatments do not work, high-dose insulin with normal blood sugar (euglycemia) treatment might be considered. This treatment enhances the ability of the heart to contract but it must be monitored due to potential side effects like lowering potassium and glucose levels in the body.
According to the situation at hand, drugs to raise blood pressure, called vasopressors, may be used while awaiting insulin therapy you could also have toxins extracted using a life-support technology known as ECMO until the effects of the drugs wear off.
If the beta-blocker you took is water-soluble (meaning it’s washed out by the kidneys easily), treatment might include several doses of activated charcoal or filtering your blood (using procedures called hemoperfusion or hemodialysis).
What else can Beta-Blocker Toxicity be?
Possible medical emergencies can include a variety of issues, such as:
- Antidepressant toxicity
- Carbamazepine toxicity (an issue related to a specific medication)
- Cardiac glycoside plant poisoning (ingestion of harmful plants affecting the heart)
- Cocaine toxicity
- Epidural hematoma in emergency medicine (a type of severe head injury)
- Hyperkalemia in emergency medicine (high potassium levels in the blood)
- Meningitis (an infection of the protective membranes around the brain and spinal cord)
- Shock, cardiogenic (a state where the heart is unable to pump sufficient blood to the body)
- Torsade de Pointes (an irregular heart rhythm)
- Toxicity, Calcium channel blockers (a potential issue with a certain class of medications)