Why hold nifedipine instead of carvedilol?

[vindy]

Hi Everyone,

This is my mini story from the beginning,

My patient's BP is 138/60 and apical HR of 57. She is on carvedilol, a beta blocker, and nifedipine, a calcium channel blocker. My instructor and I held nifedipine due to pt's low HR. So the next day, I asked my other instructor because I was so curious as to why we held nifedipine instead of carvedilol. She said that nifedipine is given to treat V-Tach and will bring the HR down very quickly compared to carvedilol. So I looked up nifedipine in my Davis drug guide, and it doesn't mention that it treats V-tach and nor does it say to hold med if pt is bradycardic, just to notify HCP if HR

(I will also ask the original instructor I gave med with to find out her reasoning. I hate to doubt teachers, but I just need to know WHY, lol)

[fromtheseaRN, BSN, RN]

i don't think the davis drug book is as detailed as it should be. in my critical care book, it states that calcium channel blockers reduce the automaticity of the SA node, and slow conduction in the AV node, thus slowing the heart rate. however, beta blockers also do that, so i'm not sure why one was held and not the other.

one thing my critical care instructor pointed out to us is that you don't necessarily need to hold the med because the HR is under a specified amount- the med is what is keeping it that low. it's all about the dr's orders.

i'm curious to see the other possible explanations!

[turnforthenurse, MSN, NP]

There are two classifications of CCBs: dihydropyridines and non-dihydropyridines.

Dihydropyridines affect primarily the arterioles and have little affect on the heart itself (doesn't affect HR, contractility, etc). Dihydropyridine CCBs can cause flushing, headache, excessive hypotension, edema and reflex tachycardia. Dihydropyridines include:

* amlodipine (Norvasc)

* felodipine (Plendil)

* nifedipine (Procardia, Adalat)

* nicardipine (Cardene)

* nimodipine (Nimotop)* (selective for cerebral blood vessels)

Because dihydropyridines can cause reflex tachycardia, you may see a beta blocker also prescribed.

Non-dihydropyridines, in addition to vasodilating, also have beta blocker-like properties (decrease HR). These include:

* verapamil (Calan)

* diltiazem (Cardizem)

Sometimes docs will write parameters for beta blockers. Typically, if SBP

I would have looked at VS trends and see if both meds were given in the past or if one was held, etc. As for your instructor's reasoning, I'm not really entirely sure. I know as a student you can't call the doctor and take orders from them, but I would have called the doc and asked about whether to hold or give the beta blocker. Nifedipine should not cause slowing of the HR.