Atropine and Amiodarone

UM Review RN, ASN, RN · Feb 7, 2009

I get mixed up between atropine and adenosine.

It helps me to know some incidental information about the medications or to create some memnonic:

http://en.wikipedia.org/wiki/Atropine

I think of Pacerone (an oral antiarrhythmic) when I think of amiodarone, and "pace" reminds me of regularity, so that's how I remember amiodarone.

hypocaffeinemia, BSN, RN · Feb 7, 2009

I cannot get these drugs straight!
When are they used and what is the difference between the two?
I know Atropine is used for bradycardia
Amiodarone is used for V tach? So does it bring the hr down?

Atropine is a potent anticholinergic. Go back to A&P and research the role of acetylcholine in the the parasympathetic nervous system. Once you review this, you will understand that atropine essentially competes against your parasympathetic processes, leading to a decrease in its tone and in increase in sympathetic response.

You know what the sympathetic response is, so this guides you to atropine's actions and its side effect profile.

Amiodarone is a bit harder to understand as there isn't one lone mechanism of action. It is a unique drug that shows some properties of beta blockers, calcium channel blockers, and sodioum and potassium-channel blockers (remember cardiac conduction in A&P?).

Basically, it slows down impulses from the SA node, slows down impulse transmission throughout the heart, and prolongs repolarization. This allows it to be used for a host of cardiac tachyarryhthmias, both of atrial and ventricular orgin.

E.R. Rookie · Feb 7, 2009

Ok so am in my critical care training, when are these used in a code?

RedCell · Feb 7, 2009

Atropine is a potent anticholinergic. Go back to A&P and research the role of acetylcholine in the the parasympathetic nervous system. Once you review this, you will understand that atropine essentially competes against your parasympathetic processes, leading to a decrease in its tone and in increase in sympathetic response.

Atropine has nothing to do with the sympathetic side of the autonomic nervous system. The increase in heart rate is because of the binding to muscarinic (specifically muscarinic 2 receptors) receptors on the vagus nerve within the SA node. The drug blocks parasympathetic tone, it does not increase sympathetic tone. Example, in a heart transplant there is parasympathetic denervation, why do you think atropine is useless, and a potent beta 1 agonist such as isoproterenol usually is needed to increase heart rate?

VegasStudent, a basic way of understanding when to use which drug in a code situation....

Atropine speeds up

Amiodarone slows down

Amiodarone prolongs the refractory period in all cardiac tissues (SA node, AV node, bundle of his, purkinje system, ventricles, even accessory bypass tracts) It can therefore be used as a possible treatment in all supraventricular (above the ventricle) and ventricular tachydysrhythmias.

RedCell · Feb 8, 2009

Also, for those who enjoy Jeopardy....Demerol (meperidine) has a chemical structure similar to atropine and was originally developed as a possible replacement for atropine. It is the only opioid that increases heart rate.

hypocaffeinemia, BSN, RN · Feb 8, 2009

Atropine has nothing to do with the sympathetic side of the autonomic nervous system. The increase in heart rate is because of the binding to muscarinic (specifically muscarinic 2 receptors) receptors on the vagus nerve within the SA node. The drug blocks parasympathetic tone, it does not increase sympathetic tone.

That's exactly what I said it does. You block the vagus and you get uninhibited sympathetic effects...

E.R. Rookie · Feb 8, 2009

Awesome, I appreciate all your help!