Difference between Epinephrine and Norepinephrine

Updated on May 31, 2017

As medications, epinephrine and norepinephrine are primarily used to control blood pressure and heart rate. As hormones, they are chemicals that play very important roles in the body’s stress responses, fuel metabolism, and blood pressure in the heart. Although very similar in function, several key features make them distinct from each other.

Definitions

Epinephrine
The molecular structure of norepinephrine and epinephrine

Epinephrine, also referred to as adrenaline, comes from the adrenal glands and some types of neurons. It is a hormone and a neurotransmitter used as a certain type of medication. Epinephrine plays an instrumental role in the human body’s flight or fight response by significantly increasing the rate of blood flow to the muscles as well as the heart’s output. It also increases pupil dilation and the body’s blood sugar. Epinephrine is produced by many animals, including some single celled organisms.

As a medication, epinephrine is used as a treatment for several conditions such as cardiac arrest, superficial bleeding, and anaphylaxis, a potentially fatal and fast-acting allergic reaction. The inhaled version is mainly used to relieve the symptoms of laryngotracheobronchitis (i.e. croup), a respiratory infection that causes swelling of the trachea. It can also be used to treat asthma when other medications won’t work. Epinephrine is usually administered intravenously by injection into the muscle or under the skin.

Epinephrine can cause side effects such as anxiety, shaking, and sweating. Heart rate and blood pressure may go up, which may also lead to abnormal heart rates. Studies about the effects of this chemical on pregnant or breastfeeding mothers remain inconclusive.

Norepinephrine, also known as noradrenaline, is an organic chemical produced in brain cell neurons or in small but powerful nuclei on other areas of the brain. It also works as a neurotransmitter outside the brain. As a medication, it is primarily administered for the treatment of people experiencing low blood pressure. Norepinephrine is also used on people suffering from low blood pressure caused by sepsis. It is administered via slow intravenous injection.

Some common side effects caused by norepinephrine are irregular or slow heart rate, headache, and anxiety. If administered incorrectly, it may cause limb ischemia, a sudden stoppage of blood flow to a limb. Norepinephrine binds and activates alpha adrenergic receptors when administered as a medication.

Epinephrine vs Norepinephrine

So what’s the difference between epinephrine and norepinephrine? Epinephrine is produced in the adrenal glands and is also called adrenaline. Norepinephrine is also known as noradrenaline and is produced in the brain cell neurons. Epinephrine is used to treat cardiac arrest, superficial bleeding, anaphylaxis, croup, and asthma. Norepinephrine is typically used to treat people experiencing very low blood pressure caused by sepsis. For epinephrine to work, it stimulates alpha 1 and 2 and beta 1, 2, and 3 adrenergic receptors. Norepinephrine, on the other hand, acts on alpha 1 and alpha 2 adrenergic receptors to promote blood vessel contraction. When used as medication epinephrine can cause rapid heart rate, shakiness, sweating, and anxiety. Pharmacological norepinephrine can cause side effects such as a slow heart rate, anxiety, and a headache.

Comparison Chart

EpinephrineNorepinephrine
Administered to treat cardiac arrest, serious allergies, asthma, etc.Administered to treat low blood pressure caused by sepsis
Acts on alpha and beta adrenergic receptorsActs on alpha adrenergic receptors
May cause anxiety, rapid heartbeat, sweating, etc.May cause slow heart rate, headache, limb ischemia