Difference Between Epinephrine and Norepinephrine


Epinephrine and Norepinephrine is often confused due to it similarity in compounds, structure and action. However, deep studies show that they are different compounds and works differently. There are certain distinctions in the two compounds which sets them apart from the other.

What is Epinephrine?

Epinephrine also called adrenaline or adrenalin is located in vertebrates and protozoans. It is a neurotransmitter and a hormone. The chemical formula of epinephrine is C9H13NO3 and its molecular mass is 183.204 g/mol.

What is Norepinephrine?

Norepinephrine also called noradrenaline is a catecholamine. It is a hormone and a neurotransmitter. The chemical formula of norepinephrine is C8H11NO3 and its molecular mass is 169.17784 g/mol. Norepinephrine was discovered in the mid-1940s by a Swedish psychologist, Ulf von Euler.

Distinctions Between Epinephrine and Norepinephrine

Though often confused, there are several distinctions between Epinephrine and Norepinephrine. It can be marked out by their different structures, effects and uses.

Epinephrine and Norepinephrine are two different but related hormones which are released during stress in the body. They are both secreted from medulla present in adrenal glands. These hormones are also found in the ends of sympathetic nerve fibers, and work as chemical mediators for conveying the impulses of the nerves to effectors organs.

Both the compounds belong to catecholamine chemical class originated from tyrosine amino acid. These hormones effectively respond to stress, blood pressure in arteries, and metabolism. They help in increasing the level of free fatty acids circulating in the body and stores it for times when a person undergoes stress or excess alertness. Norepinephrine works by narrowing the blood vessels and increasing the levels of blood pressure and sugar levels.

Both the hormones are similar but its structure varies slightly. Epinephrine is also known as adrenaline and its structure contain a hydrogen atom. Norepinephrine is also known as noradrenaline and its structure is built by the methyl group. The difference in structure makes their effects to vary.

The medullas present in adrenal glands secrets eighty percent of epinephrine and twenty percent of norepinephrine. The effects of epinephrine are largely controlled by the adrenal medulla. However in the sympathetic nerves, norepinephrine dominates largely, thus the effects of norepinephrine are controlled mostly by the sympathetic nerves.

Epinephrine is sometimes called by another name as emergency hormone as it is released when the body is in stress. The stimulant present in epinephrine prepares the animals for fight or flight. The purest form of epinephrine compounds are used in clinics. They are produced from the adrenal glands of animals that are domesticated or prepared synthetically.

Amino acid tyrosine produces norepinephrine in the body and epinephrine is formed by norepinephrine. Both the compounds differ in their adrenergic reception to receptor types like alpha1, alpha2, Beta1, and Beta2.

Norepinephrine forms bond basically with receptors like alpha and Beta1. Epinephrine bonds with the same reactors like norepinephrine but it connects more with alpha reactors in comparison to norepinephrine. Both compounds react equally with Beta1 receptors. Thus, the effects of these compounds in many tissues are similar.

The two chemical compounds are identical as they have similar composition, uses and effects and thus they are categorized as sympathomimetic agents.

Though the two compounds are similar in their actions certain effects in the compounds differ. Epinephrine constricts the tiny blood vessels in their networks but widens the liver’s and skeletal muscles’ blood vessels. It supplies the muscles with nutrients and creates fuel for a short energy burst. Norepinephrine constricts almost all the blood vessels.

Both the compounds prevent the bladder from emptying and disturb the digestive process.

Clinically both epinephrine and norepinephrine are effectively used in many procedures, most commonly in patients who are undergoing severe medical distress. Patients who are suffering from allergy can use epinephrine for quick relief from allergic reactions until they get medical help.

Epinephrine is injected into the heart of a patient suffering from cardiac arrest for stimulating his heart activity. Norepinephrine is given to the patient suffering from low blood pressure, those that results in shock. Norepinephrine is supplemented through intravenous infusion. Only epinephrine widens the respiratory passage to allow air to move in and out freely.

Epinephrine compound widens bronchioles thus giving relief to patients suffering from asthma and other respiration related problems. It is also useful in curing allergies caused by medicine reactions, hay fever and hives. Norepinephrine is given to patients who are suffering from depression and other mental health problems.

One major difference between these two compounds is that norepinephrine acts in the brain like a psychoactive compound but epinephrine does not.

Norepinephrine is a useful medicine for people suffering with severe hypotension. Epinephrine is useful for people suffering from anaphylaxis and superficial bleeding.

Epinephrine is effectively used for treating croup and works as a local anesthetics. It is added to many local anesthetics to slow down the process of absorption and prolong the effect of anesthetic agent. Norepinephrine relieves problem of overactive thyroid.

If norepinephrine is given in a high dose, especially along with other vasopressors, it may result in limb ischemia and death. It also results in headache, slow heart rate, sweating, and sensitivity to light, backache, stabbing sensation in chest, etc. Adverse effects of epinephrine includes decreased sensation in touches, arm and back pain, blurred vision etc.

Epinephrine and norepinephrine thus have different structures, uses and effects and can be differentiated through them. Though they are similar compounds they behave differently. Both the compounds have different chemical formula and molecular mass.