Sympathomimetic Drugs: What You Need to Know

SimpleNursing Editorial Team Oct 1, 2018
anaphylaxis sympathomimetic drugs

Here’s a real-life case you might run into that ends in administering sympathomimetic drugs:

While eating at a restaurant, your client suddenly developed an anaphylactic reaction after devouring a plateful of mixed seafood. After a few minutes, the person has a severe allergic reaction. 

The moment a person experiences anaphylaxis due to something they ate, inhaled, or came in contact with, the result would be decreased oxygen perfusion to the body.

In Pharmacology class, you’ve probably run into drugs related to anaphylaxis, including sympathomimetics. Before jumping into sympathomimetic drugs, let’s go over anaphylactic drugs.

Anaphylactic Drugs

It doesn’t matter if it’s a heart attack, a stroke, a deep vein thrombosis, or a pulmonary embolism, the body becomes compromised for as long as the pathways for blood-rich oxygen are blocked.

In the case of anaphylaxis, the blood vessels widen, causing low pressure, which equates to low perfusion, and essentially low oxygen supply. Therefore, anaphylactic drugs (including sympathomimetics) aim to reverse this consequence.

What are Sympathomimetic Drugs?

One of the types of anaphylactic drugs is the sympathomimetic drug. Sympathomimetic drugs are meant to mimic the role of the sympathetic nervous system, acting on the fight and flight response. 

Tapping the sympathetic nervous system will cause increased blood flow to the three main organs in the body – the lungs, the heart, and the brain. Thereby decreasing the rest and digest phase and getting the required amount of oxygen where the body needs it. 

This is how sympathomimetic drugs are created – to imitate the parasympathetic response system.

The sympathomimetic drugs that are used in hospitals are:

  • Epinephrine
  • Isoproterenol
  • Ephedrine

Administration of either one of these drugs would immediately cause vasoconstriction, increasing perfusion by shunting blood to the brain, lungs, and heart.


Among these three kinds, epinephrine is the most common medication used in any healthcare setting, especially in emergency cases. Epinephrine is what’s given first during a cardiac arrest to jumpstart the heart that stopped beating. 

The body naturally creates epinephrine, also known as adrenaline. Therefore, epinephrine is just adrenaline in a bottle.

How to Remember Epinephrine

Epinephrine or sympathomimetic drugs have several effects on the body, to quickly recall what these drugs do to the body, remember the acronym NASCAR.

N – nervousness

A – anxiety

S – sugar in the blood is increased

C – cardiac arrest

A – allergic reaction

R – respiratory bronchodilator

Epinephrine Nursing Considerations 

Keep the following in mind when administering epinephrine:

  • Administer as soon as possible after recognizing the signs and symptoms of anaphylaxis.
  • Epinephrine is most effective when given up to thirty minutes after exposure to the triggering allergen.
  • Epinephrine potentially has negative interactions with analgesics, antidepressants, and antibiotics.


Isoproterenol is a synthetic adrenergic agent used to treat asthma and bradycardia (slow heart rate). It mimics the effect of epinephrine and is also for cardiac failure, shock, COPD, and glaucoma.

Isoproterenol can be administered via inhalation, nebulation, or injection, but should not be taken in patients with angina.

ventricular arrhythmias requiring inotropic treatment, tachyarrhythmias, or heart block brought on by digitalis poisoning.


Ephedrine is a (central nervous system) CNS stimulant that’s used to guard against low blood pressure during anesthesia. It’s found in a plant called ephedra, which mimics the effect of epinephrine.

Intravenous use has a quick onset, whereas injection into a muscle can take 20 minutes, and taking a medication orally can take an hour to take action. Ephedrine lasts roughly an hour after injection and can last up to four hours after oral administration.

Ephedrine shouldn’t be taken with some antidepressants, including norepinephrine-dopamine reuptake inhibitors (NDRIs), as this raises the possibility of symptoms brought on by high norepinephrine levels in the blood.

Sympathomimetic Effects

Sympathomimetic drugs stimulate the body’s oxygen and blood perfusion by imitating the sympathetic nervous system’s effects. The introduction of epinephrine to the body can cause adverse reactions like nervousness, anxiety, and increased blood sugar. 

Sympathomimetic drugs also cause headaches, palpitations, tremors, and dizziness.

Aside from cardiac arrest, epinephrine is also used for the anaphylactic reaction that can be caused by several factors like food, medication, latex, and insect stings. 

A secondary effect of sympathomimetic drugs is respiratory bronchodilation or lung expansion from the shunting of blood to the respiratory tract.

Learn More Pharmacology with Us

So that’s sympathomimetic drugs in a nutshell – for your nursing coursework and real-life execution against anaphylaxis.

For those who want to brush up on the topic of nervous system disorders and drugs used to treat them, we have plenty of related videos, custom quizzes, and study guides.

SimpleNursing has everything you need to help ace your next course or exam if you want to boost your pharmacology game.

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