by billythekid

I have a question:

At my institution, Cardizem drips are ordered to run at 10 mg/hr, while our Cardene drips are ordered as titrate to SBP 130. Why the difference in dosing/parameters between the two?

Understanding both are Ca channel blockers, I've been told (of course I asked) that Cardene has more specific effects on the Ca receptors located in the arteries (effecting vasodilatation or vasoconstriction), whereas Cardizem has an effect on these same receptors but also has a more negative inotropic effect d/t reduced contractility and decreased chronotropy. I've gotten 10 explanations as to the differences of these two drugs and their subsequent dosage/parameter variations. Either their explanations aren't 100% on target, or I'm just having a mental block processing the information... anyone care to elaborate please?

Why is Cardizem written at a specific rate, while Cardene is titrated to SBP 130?

Thanks!
Bill

Re: Question regarding dosing of Cardizem drip vs Cardene drip

Both generally have ballpark starting rates, about 10/hr. They just have different targets.

Nicardipine is a dihydropyridine and primarily dilates smooth muscle. It is an antihypertensive so it's titration is only by target SBP. It has a ceiling, so additional agents may be necessary.

Dilt is a benzothiazepine, primarily used for ventricular rate control in tachyarrhythmias. The starting dose is somewhat weight based (the initial bolus should be 0.25-0.35 mg/kg), so the initial drip rate mirrors this dose. It also maxes, around 25-30/hr.

There's no hard and fast rule about what dose you start at, but pts w/ risk for sudden hypotension (hypovolemia, sepsis) and bradycardia should be titrated with caution for cardene and dilt respectively.

Re: Question regarding dosing of Cardizem drip vs Cardene drip

Bill,
You typically see diltiazem used for rate control in tachy arrythmias (i.e. afib) don't see it used for pressure control mostly.

Cardene is a calcium channel blocker but it's use is typically used for pressure control (lots of facilities use cardene in place of nipride on renal patients).

Re: Question regarding dosing of Cardizem drip vs Cardene drip

Originally Posted by TakeBack

Both generally have ballpark starting rates, about 10/hr. They just have different targets.

Nicardipine is a dihydropyridine and primarily dilates smooth muscle. It is an antihypertensive so it's titration is only by target SBP. It has a ceiling, so additional agents may be necessary.

Dilt is a benzothiazepine, primarily used for ventricular rate control in tachyarrhythmias. The starting dose is somewhat weight based (the initial bolus should be 0.25-0.35 mg/kg), so the initial drip rate mirrors this dose. It also maxes, around 25-30/hr.

There's no hard and fast rule about what dose you start at, but pts w/ risk for sudden hypotension (hypovolemia, sepsis) and bradycardia should be titrated with caution for cardene and dilt respectively.

Thanks for the responses!

I think I need to clarify (rephrase) my original question:

Since they are both calcium channel blockers, what causes diltiazem and nicardipine to have different physiologic responses ie Cardene most often utilized for pressure control and Cardizem utilized for rate control. Is Cardizem *not* as effective in controlling pressure, and if so, why? etc

Do they both affect the same receptors, or since Cardene is labeled 'selective' ca blocker, what are the differences in the pharmacodynamics? I've been reading up to contrast the two, but the descriptions of their actions are quite similar and do not account for why one is used over the other for hypertension vs rate control.

Thanks!

Re: Question regarding dosing of Cardizem drip vs Cardene drip

Originally Posted by billythekid

Thanks for the responses!

I think I need to clarify (rephrase) my original question:

Since they are both calcium channel blockers, what causes diltiazem and nicardipine to have different physiologic responses ie Cardene most often utilized for pressure control and Cardizem utilized for rate control. Is Cardizem *not* as effective in controlling pressure, and if so, why? etc

Do they both affect the same receptors, or since Cardene is labeled 'selective' ca blocker, what are the differences in the pharmacodynamics? I've been reading up to contrast the two, but the descriptions of their actions are quite similar and do not account for why one is used over the other for hypertension vs rate control.

Thanks!

Nicardipine functions mainly on the vascular smooth muscle. This class has been shown to have some EP effects on the SAN and AVN but not that is clinically significant at the doses used for hypertesion tx.
Diltiazem has strong negative effects on AVN conduction, as opposed to cardene, the reason it is used as an acute rate control drug. It also causes vasodilation. It is preferable for rate control b/c it has a less profound hypotensive effect than other CCBs like nifedipine or BBs like metoprolol.

Nicardipine = vasodilation
Diltiazem = rate control + some vasodilation

They all work on calcium channels, but the structure of the drug influences their different activities as described above.

The detailed clinical pharm is not something you probably need to worry too much about at the bedside. These are both widely used drugs and have pretty predicatable effect profiles.

Re: Question regarding dosing of Cardizem drip vs Cardene drip

Originally Posted by TakeBack

Nicardipine functions mainly on the vascular smooth muscle. This class has been shown to have some EP effects on the SAN and AVN but not that is clinically significant at the doses used for hypertesion tx.
Diltiazem has strong negative effects on AVN conduction, as opposed to cardene, the reason it is used as an acute rate control drug. It also causes vasodilation. It is preferable for rate control b/c it has a less profound hypotensive effect than other CCBs like nifedipine or BBs like metoprolol.

Nicardipine = vasodilation
Diltiazem = rate control + some vasodilation

They all work on calcium channels, but the structure of the drug influences their different activities as described above.

The detailed clinical pharm is not something you probably need to worry too much about at the bedside. These are both widely used drugs and have pretty predicatable effect profiles.

I've been searching for the answer you just provided for the past week or so.... very much appreciated!