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My pharmacology professor glossed over the mechanism that causes edema besides briefly discussing after/preload. If Calcium channel blockers and beta blockers both are negative ionotropes then why isn't heart failure some form of adverse effect in both drug classes?

Justin Edward
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    Why do you think the mechanism is heart failure? Peripheral edema can be caused by other things, and in this case I believe it is. – Carey Gregory Nov 07 '22 at 23:37
  • Good point. I was hyper focused on heart failure as it is what we were learning in class. What other mechanism would the calcium channel blockers be using? Does it have something to do with the blocking of the channels in the blood vessels? – Justin Edward Nov 09 '22 at 00:06
  • Consider what will happen if arteriolar resistance is decreased but resistance remains the same in the venous circulation. Or just google calcium channel blockers + edema and you will find this. Questions here are required to demonstrate prior research, so I recommend that you [edit] your question and add this link along with a relevant quote from the article. – Carey Gregory Nov 09 '22 at 00:17
  • Sorry I am new here. I didn’t mean to pose my question the wrong way. – Justin Edward Nov 09 '22 at 00:43
  • That's okay, many new users do the same. Just follow my suggestions and you're good. Your question has upvotes so people think it's a good question. – Carey Gregory Nov 09 '22 at 01:43

1 Answers1

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It has to do with different mechanism of action of both substances. Both calcium channel blockers and beta blockers are used to lower blood pressure, but the ways, how the hypotensive effect is achieved, are different.

As a first approximation, the arterial blood pressure PA evolves with

PA = PV + R * dV/dt,

where PV is central venous pressure, R is total peripheral resistance and dV/dt is cardiac output.

Calcium channel blockers have vasodilatory action, i.e. they lower R. Beta-blockers act mainly on the heart so that they decrease dV/dt. Both mechanisms lower blood pressure, but the ways are different.

Different are also their side effects. Beta-blockers may lead to bradycardia (and other problems), and calcium channel blockers increase the hydrostatic pressure in the precapillary circulation, thereby permitting fluid shifts into the interstitial compartment. Beta-blockers have even a slight vasoconstrictor effect.

This is the reason why patients on calcium channel blockers are more prone to oedema than persons on beta-blockers.

References

  1. Sica D. Calcium channel blocker-related periperal edema: can it be resolved? J Clin Hypertens (Greenwich). 2003 Jul-Aug;5(4):291-4, 297. doi 10.1111/j.1524-6175.2003.02402.x. PMID 12939574.

  2. Makani H, Bangalore S, Romero J, Htyte N, Berrios RS, Makwana H, Messerli FH. Peripheral edema associated with calcium channel blockers: incidence and withdrawal rate--a meta-analysis of randomized trials. J Hypertens. 2011 Jul;29(7):1270-80. doi 10.1097/HJH.0b013e3283472643. PMID 21558959.

jwdietrich
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