Tox Tuesday: Propranolol

Commonly used to treat high blood pressure and chest pains causing heart attack, propranolol was discovered in 1962 and was the first successful type of drug developed known as a beta blocker. Beta blockers work by relaxing blood vessels and slowing the heart rate to improve blood flow in a person’s body.

Due to these effects, propranolol is also used today to treat patients with anxiety and panic disorders as well as other conditions such as migraines, irregular heartbeat and glaucoma. Propranolol has also been used in animals to control their heart rate and improve heart performance in certain types of disease.

While there are several uses for propranolol, overdose from the drug is a common fear of health professionals. In a study published in the Journal of Clinical Toxicology, propranolol killed two of the 58 patients involved in the study who were given high amounts of the drug, and caused cardiac arrest, seizures and coma in others. Conclusions from this study state propranolol should not be used in patients who are a risk of self-poisoning, nor should it be used by those who have lung problems or a slow heart rate.

Recently however, the drug has made headlines both in the U.S. and abroad for its ability to treat other serious conditions like post-traumatic stress disorder (PTSD) and is even credited with saving the life of an infant in the United Kingdom (UK). 

According to a story published by Mail Online, at just three-weeks old, Georgia Gibson was diagnosed with a tumor developing rapidly behind the optic nerve of her left eye. If left untreated for another 10 days, the infant’s doctor said removal of the tumor would have been be impossible. Previously, shrinking of the tumor would have to be done through traditional cancer treatments, but instead the doctor put Georgia on a trial for propranolol.

Twenty-four hours later, the drug had drastically reduced the swelling around her eye and after an 18-month period of home treatment, Georgia made a full recovery. Although the tumor is still present, doctors are confident that it will continue to shrink naturally and is no longer a threat to her health.

Based on information from the National Institute of Health, beta blockers like propranolol work because they target beta receptors that are found on cells of the heart muscles, airways, arteries, kidneys, and other tissues that are part of the sympathetic nervous system. When beta receptors are stimulated by epinephrine (adrenaline), they produce the feelings you typically feel in a stressful situation. However, when beta blockers, such as propranolol, are introduced into the body, they interfere with the binding the receptor has to the adrenaline and other stress hormones. This in turn weakens their effects and the overall feelings of stress.

Recently, an article in Scientific American discussed the drug’s ability to use in treating patients with PTSD, especially military veterans. In such cases, propranolol can dampen the emotional strength of a memory and thus reduce the potential trauma of that memory moving forward. This is different from other drugs that treat PTSD because it addresses the root cause of the disorder rather than its symptoms.

Similar findings discussed in Defense One have led to controversial theory known as “memory reconsolidation,” in which researchers consider the possibility of actually being able to alter memories through the use of propranolol. In the article, one researcher explains that memories are not necessarily fixed, but rather can be changed long after they are stored. This can happen because seemingly stable memories re-enter an unstable state when they are retrieved in someone’s mind. If manipulated or modified with the use of propranolol at this point, they could then be re-stored with the new information incorporated.

In another study, published in Nature Neuroscience, volunteers were asked to generate fear memories after being subjected to loud noises and images of spiders. One group was given propranolol before recalling the fearful experience, while the other was given placebo pills. When the two groups were reminded of the memory days after the experiment began, those who had taken propranolol showed markedly less fear than those who had not.

In a recent article by the FDA, the use of propranolol has also been found to be effective in patients suffering from migraines when they take the drug before the migraine actually begins. Because sufferers are advised to keep a track of the common triggers that cause their migraines, the drug has been shown to be able to stop the migraine before it even starts.

Because of its calming effects, propranolol is often used by musicians and other performers to prevent stage fright and is also taken by surgeons to maintain steady hands during surgery. Propranolol is also popping up in the e-sports world, as a report by New Scientist discusses professional video gamers using the drug to improve their concentration and stay calm under pressure. This is causing similar issues of doping that are present in other professional sports today.

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