Calcium Antagonists: Calcium Channel Blockers Quiz
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Questions and Answers

Which subunit of the voltage-gated calcium channel do Calcium Antagonists bind to?

  • Gamma
  • Alpha1 (correct)
  • Beta1
  • Alpha2

    • What is the mechanism of action of Calcium Antagonists in preventing the diffusion of Ca2+ through the pore in an open channel?

  • Enhancing calcium diffusion
  • Indirectly preventing diffusion by binding to the alpha1 subunit (correct)
  • Directly blocking the calcium pore
  • Binding to the gamma subunit

    • Which type of Calcium Channel Blocker is preferentially acting on the heart?

  • Dihydropyridines
  • Verapamil (correct)
  • Nifedipine
  • Amlodipine

    • What is one example of a Benzothiazepine Calcium Channel Blocker?

    <p>Diltiazem</p> Signup and view all the answers

    In which type of angina would reducing coronary artery spasm be beneficial?

    <p>Variant angina</p> Signup and view all the answers

    What is the main pharmacological effect in smooth muscles caused by Calcium Channel Blockers?

    <p>Arterial vasodilation</p> Signup and view all the answers

    What is the primary reason for the contraindication of Calcium Channel Blockers (CCB) in heart failure?

    <p>They can worsen cardiac contractility.</p> Signup and view all the answers

    What is the mechanism behind the reflex increase in sympathetic activity caused by Calcium Channel Blockers (CCB)?

    <p>Vasodilation-induced baroreceptor reflex.</p> Signup and view all the answers

    Which of the following is an adverse drug reaction associated with Calcium Channel Blockers?

    <p>Peripheral edema.</p> Signup and view all the answers

    How does grapefruit interact with Calcium Channel Blockers?

    <p>It decreases CCB metabolism.</p> Signup and view all the answers

    Which of the following statements is true regarding the clinical use of Dihydropyridine Calcium Channel Blockers?

    <p>They protect ischemic tissues effectively.</p> Signup and view all the answers

    What is a characteristic of Calcium Antagonists' pharmacokinetics?

    <p>Well absorbed when taken orally except in special circumstances.</p> Signup and view all the answers

    What is a contraindication for all calcium channel blockers in the presence of overt heart failure?

    <p>Congestive heart failure</p> Signup and view all the answers

    What adverse drug reaction is most frequently associated with nifedipine among the calcium channel blockers?

    <p>Peripheral edema</p> Signup and view all the answers

    Which calcium antagonist does not increase mortality in patients with heart failure due to nonischemic left ventricular systolic dysfunction?

    <p>Amlodipine</p> Signup and view all the answers

    What type of interaction occurs between calcium channel blockers and grapefruit?

    <p>Synergistic interaction</p> Signup and view all the answers

    Which clinical condition is not a common use for calcium channel blockers?

    <p>Heart failure</p> Signup and view all the answers

    Which calcium antagonist has a long half-life and is typically dosed once daily?

    <p>Amlodipine</p> Signup and view all the answers

    Study Notes

    Calcium Antagonists Overview

    • Bind primarily to the alpha-1 subunit of voltage-gated calcium channels.
    • Mechanism of action involves blocking the Ca2+ influx by preventing channel opening, thereby inhibiting calcium entry during depolarization.

    Types and Examples

    • Dihydropyridine calcium channel blockers preferentially affect vascular smooth muscle, reducing blood pressure.
    • An example of a Benzothiazepine calcium channel blocker is diltiazem.

    Clinical Applications

    • Reducing coronary artery spasm is beneficial in Prinzmetal's angina.
    • Calcium channel blockers primarily cause vasodilation in smooth muscles, decreasing overall vascular resistance.

    Contraindications and Considerations

    • Contraindicated in patients with heart failure due to potential for worsening symptoms and increasing preload.
    • Reflex sympathetic activity is stimulated due to decreased blood pressure, as the body compensates with increased heart rate and contractility.

    Adverse Effects and Interactions

    • Common adverse drug reactions include peripheral edema, flush, and hypotension; especially noted with nifedipine.
    • Grapefruit juice can significantly increase plasma concentrations of calcium channel blockers, enhancing effects and side effects.

    Clinical Use and Pharmacokinetics

    • Dihydropyridine calcium channel blockers are primarily used for hypertension and angina.
    • Calcium antagonists exhibit varied pharmacokinetics; for instance, amlodipine has a long half-life, allowing for once-daily dosing.
    • All calcium channel blockers are contraindicated in overt heart failure cases to avoid exacerbation.

    Notable Conditions and Interactions

    • Calcium channel blockers are not typically used for heart failure management.
    • No calcium antagonist has been shown to increase mortality in patients with nonischemic left ventricular systolic dysfunction.

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    Description

    Test your knowledge on Calcium Channel Blockers including the classes, mechanisms of action, and pharmacological effects of calcium antagonists such as phenylalkylamines, dihydropyridines, and benzothizepines.

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