Epinephrine and norepinephrine, which are also known as adrenaline and noradrenalin respectively, belong to catecholamine which in turn derives from the amino acid tyrosine. Epinephrine and norepinephrine are chemicals that control metabolic responses in the body, including blood vessel dilation, oxygen release to the muscles, and blood pressure change. As you may be aware, they are released when the body needs to respond to emergencies and then recover afterwards. But with such similar names, what is the difference between the two?
Epinephrine vs. Norepinephrine: Source and Structure
Epinephrine is released by an area called the adrenal medulla. This happens when preganglionic sympathetic nerves are activated in this gland by a major stress, such as exercise, heart failure, emotional stress or something similar. The adrenal medulla produces 20% of norepinephrine and the rest of norepinephrine comes from the ends of sympathetic nerve fibers. Epinephrine is controlled by adrenal medulla, while norepinephrine is mainly controlled by sympathetic nerves. They have another significant difference on a molecular level – epinephrine has a methyl group; norepinephrine contains just a hydrogen atom. This structural difference makes them act differently.
Epinephrine vs. Norepinephrine: Function
There are important differences between the two – for example, norepinephrine can act as a psychoactive compound in the brain but epinephrine can’t. When a person is under physical or emotional stress, the adrenal gland releases both to prepare for a response. When epinephrine is released into the blood stream, it constricts blood vessel and increases blood pressure. It then increases energy production by using glucose which is released in response to norepinephrine. The norepinephrine, on the other hand, promotes blood circulation to the muscles to give them short energy bursts. It also increases blood pressure and heart rates. In the brain, it can promote alertness and vigilance. A series of reactions occur until the crisis is over and the release of the two hormones slows.
Epinephrine vs.Norepinephrine: Medical Use
Epinephrine narrows blood vessels and opens airways. This makes it very useful in times of emergency to reverse severe low blood pressure, wheezing, severe dermatitis, hives, and allergic reactions. An injection is often used when a patient has a severe reaction to bug bites or stings, foods, drugs, or other triggers. It can also be used to treat exercise-induced anaphylaxis.
Norepinephrine, similar to adrenaline, can be used to constrict the blood vessel and increase blood pressure and glucose levels. It is used to treat life-threatening hypotension (low blood pressure) that may happen in conjunction with other medical conditions. It is often used with CPR. Additionally, it can be used to treat depression or other mental health conditions because of its effects on the brain.
Epinephrine vs. Norepinephrine: Side Effects
Although extremely helpful in emergency settings, they are not without their side effects. Below are some of the common side effects that could happen.
Epinephrine Side Effects
Due to its stimulating effects, it isn’t surprising that the side effects would be related to stimulation. These would include:
- Quickened or pounding heartbeats
- Pale skin, sweating, nausea, vomiting
- Dizziness, weakness, tremors
- Throbbing headache
- Nervous, anxious, or fearful feelings
Avoid this medicine if past use caused allergic reactions to get worse.
Norepinephrine Side Effects
The serious side effects include:
- Pain, burning, irritation or skin changes of the injection site
- Numbness, weakness, cold feelings
- Slow heart rate, blue lips or fingernails, trouble breathing
- Problems with vision, speech or balance
- Dangerously high blood pressure
- Little or no urinating
- Buzzing in the ears
- Anxiety, confusion, chest pain, seizure
Get immediate help if the use causes any signs of allergic reaction, such as tongue or throat swelling, hives and difficulty breathing.