Skip to main content

Understanding Adrenaline Dosage

Have you ever administered adrenaline for anaphylactic shock? I've never had the unfortunate need to. I'm sure anyone who ever does will forever remember the correct dosage. But for me, it is always a confusion. Every time I vaccinate someone at my clinic, I look up the dose of adrenaline just to be sure.

The first problem is the dilutions. Dosages of adrenaline are (or were) mentioned in dilution. 1:1000 & 1:10000. There begins the confusion.

Firstly, let us understand where the 1000 comes from in 1:1000. Have you seen a small vial of adrenaline? That is 1mL. It has effectively 1mg of epinephrine/adrenaline. But why is it called 1:1000? Because 1mL of water = 1g of water = 1000mg. So, the 1:1000 actually refers to 1mg of adrenaline : 1000 mg of water. Unnecessarily complex!

All you had to say was 1mg in 1mL. And that is why this labeling is now being followed in some countries.

So, there you have a small vial - a 1mL vial - with 1mg of adrenaline in it.

Now, let us look at the other form epinephrine comes in. Epinephrine also comes in a big syringe of 10mL. But even this 10mL contains only 1 mg of adrenaline. The total amount of adrenaline in this 10mL form is the same as a small vial.

What is different then? Well, when the volume increases without increase in amount, the concentration drops. The 10mL form is more dilute than the small vial. Can you guess the dilution? It is 1:10000 or more easily expressed as 1mg in 10mL.

So, the first thing to internalize is that the small 1mL vial we see has 1mg of adrenaline (it may say 1.8mg of an adrenaline salt, but the effective amount of adrenaline is 1mg). And this is a concentrated form of adrenaline.

What that also means is that the 1mg/1mL adrenaline is never used directly IV! The reason is that this can cause an arrhythmia or other damages to the heart muscles.

If you're bored reading text, watch this youtube video telling these same things.



Now, the dilute form and the concentrated form are for slightly different uses. The concentrated form is given IM in anaphylactic shock. The dilute form is given IV in cardiac arrest.

When giving IM adrenaline for anaphylactic shock, the dosage in adults is almost always 0.5mg (0.5mL of the concentrated vial). If you can remember this fact it is easy to calculate the pediatric dose as well. The adult dose can be thought of as if it applies to a 50kg person. So 0.5mg for 50kg = 0.01mg/kg and that is the pediatric dose. (This 50kg adult approximation applies for many other drugs in calculation of pediatric dose. Let me know in comments below about other drugs that can be calculated this way).

When giving in cardiac arrest, in which case the dilute form (1mg in 10mL) is used, the adult dose is the entire 1mg (or 10mL) given intravenous and repeated based on the protocol you follow.

That is all there is to know. Just a 0.5mg and a 1mg.

Comments

MaaLuSreya said…
Really awesome explanation by you @Akshay S Dinesh...but 1 more reason for administration of 0.5ml adrenaline IM is due to its ease to administer without wasting time over securing an IV line and putting the patient's life in danger.
MaaLuSreya said…
👌👌👌👌👌

Popular posts from this blog

"Risks" vs Risks

Decision making is almost always complicated by uncertainties. The more information that can provide context, the more stakeholders that are part of the decision, the better the chances of reaching a good decision.

In the past few weeks, world leaders have had to make very difficult decisions. Lock down entire country? Put money into healthcare? Risk economic disasters to prevent health disaster?

I guess the biggest problem they would have faced in making these decisions is uncertainty. Because medicine is a field of uncertainties. The first thing a doctor learns when helping patients is that they can never be sure of anything other than the fact that they have to act. Diseases, cells, organisms, molecules, environment, human behaviour - there are a lot of moving parts in medicine. Parts that you can't control. Parts that you can't even predict.

A doctor is a performance artist who uses an imperfect science to help alleviate suffering. In Osler's words, "Medicine is …

Anatomy paper 1 RS 2 RGUHS 2013 December question paper

My roommate says this one was easy too.

Pharmacology RGUHS question papers December 2012

Try solving these

Lessons One Should Learn From Shehla Sherin's Death

If you do not avoid news like me, you would have heard about the tragic death of a 10 year old in Wayanad a couple of days ago. You can search the name and find the story on your own, but a few facts are established already.

Shehla Sherin had her foot go into a hole on the floor of her classroom and was afraid a snake bit her in that incidentThere was delay in taking her to the hospitalAnti-Snake venom was not administered at the local hospital, and the child was referred to a tertiary care center at least an hour away.Child died on the way. I won't unnecessarily go into speculations on what other things happened on that fateful day, but having managed emergency department in a rural hospital for over an year, I will use this sad death to illustrate two very important lessons for every doctor.

Lesson 1: Never take any complaint lightly, even if the circumstances lead you to think otherwise There are two ways patients can come in. There are people who exaggerate, and people who down…