Calcium Channel Blockers (CCBs)

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Overview of Calcium Channel Blockers (CCBs)

1. Classes & Agents

ClassExamplesMain EffectsSide EffectsKey Indications
Dihydropyridines (DHPs)Short: nifedipine, clevidipine, nimodipine
Intermediate: nitrendipine, nicardipine, lercanidipine
Long: amlodipine, felodipine		Potent vasodilators (arteries)
Minimal myocardial depression		Headache, flushing, dizziness, peripheral edema, reflex tachycardia, gingival hyperplasiaHypertension, angina (stable & vasospastic), Raynaud’s, hypertensive emergencies (nicardipine, clevidipine), SAH vasospasm prevention (nimodipine), tocolysis, gestational hypertension
Non-Dihydropyridines (NDHPs)Benzothiazepines: diltiazem
Phenylalkylamines: verapamil, gallopamil		Moderate vasodilation
Negative inotropy, chronotropy, dromotropy		Bradycardia, AV block, reduced contractility, constipation (verapamil), hyperprolactinemia, gingival hyperplasiaHypertension, supraventricular arrhythmias (AF, SVT), angina, HOCM, migraine/cluster headache (verapamil)

2. Mechanism of Action

  • Block L-type Ca²⁺ channels in cardiac & vascular smooth muscle → ↓ Ca²⁺ influx

  • Effects:

    • Vasodilation → ↓ afterload, ↓ BP

    • Negative inotropy → ↓ cardiac output

    • Negative chronotropy → ↓ heart rate

    • Negative dromotropy → slows AV conduction

  • DHPs: act mainly on arteries

  • NDHPs: act mainly on heart (verapamil > diltiazem)


3. Adverse Effects

DHPs:

  • Headache, flushing, dizziness

  • Peripheral edema (esp. amlodipine)

  • Reflex tachycardia (esp. nifedipine)

  • Gingival hyperplasia

NDHPs:

  • Bradycardia, AV block

  • Reduced contractility

  • Constipation (verapamil)

  • Hyperprolactinemia

  • Gingival hyperplasia

4. Contraindications

  • All CCBs: hypersensitivity, severe hypotension, acute coronary syndrome

  • DHPs: HOCM, severe aortic stenosis

  • NDHPs: heart failure with reduced EF, bradycardia, 2°/3° AV block, WPW, sick sinus syndrome, combination with beta-blockers (risk of AV block & bradycardia)

✅ Key Exam Pearls:

  • Amlodipine → Arteries (DHPs)

  • Verapamil → Ventricles (NDHPs)

  • Short-acting nifedipine → can worsen angina due to reflex tachycardia

  • Nimodipine → specific for SAH vasospasm prevention

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