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# Calcium Channel Blockers (CCBs)
## Overview
Calcium channel blockers (CCBs) inhibit the influx of calcium ions into cardiac and vascular smooth muscle. They are divided into two main categories: **Dihydropyridines** (e.g., amlodipine, nifedipine), which are potent vasodilators with minimal negative inotropic effects, and **Non-dihydropyridines** (e.g., diltiazem, verapamil), which possess significant negative chronotropic and inotropic effects.
## Primary Indications
* **Dihydropyridines:** Hypertension, stable angina, Prinzmetal’s angina.
* **Non-dihydropyridines:** Supraventricular tachycardias (SVT), atrial fibrillation rate control, hypertension, chronic stable angina.
## Adult Dosing
* **Amlodipine:** 5 mg to 10 mg PO once daily. Max: 10 mg/day.
* **Nifedipine (ER):** 30 mg to 90 mg PO once daily. Max: 90 mg/day.
* **Diltiazem (ER):** 120 mg to 360 mg PO daily (frequency depends on formulation). Max: 480 mg/day.
* **Verapamil (ER):** 180 mg to 480 mg PO daily in divided doses. Max: 480 mg/day.
## Pediatric Dosing
Dosing is highly dependent on age, weight, and indication; institutional protocols or specialized resources (e.g., Neofax, Harriet Lane) should always be consulted.
* **Amlodipine:** Typically 0.1 mg/kg/day (start). Max: 0.6 mg/kg or 10 mg/day.
* **Diltiazem/Verapamil:** Not first-line for pediatrics. Dosing varies significantly by arrhythmia protocol; consult pediatric cardiology.
## Dose Adjustments
* **Hepatic Impairment:** Reduce starting doses for diltiazem, verapamil, and nifedipine due to extensive hepatic metabolism.
* **Renal Impairment:** Generally safe; no standard dose reduction required.
## Contraindications
* **All CCBs:** Known hypersensitivity.
* **Non-dihydropyridines:** Second/third-degree AV block (without a pacemaker), sick sinus syndrome, severe heart failure (specifically with reduced ejection fraction).
## Adverse Effects
* **Common:** Peripheral edema (dihydropyridines), constipation (verapamil), gingival hyperplasia, dizziness, flushing.
* **Serious:** Bradycardia/heart block (non-dihydropyridines), worsening of heart failure, severe hypotension, reflex tachycardia.
## Key Drug Interactions
* **CYP3A4 Inhibitors/Inducers:** Strong inhibitors (e.g., clarithromycin, ritonavir) increase CCB levels; inducers (e.g., rifampin, phenytoin) decrease levels.
* **Beta-blockers:** Concomitant use with non-dihydropyridines increases the risk of heart block and severe bradycardia.
* **Simvastatin:** Limit to 20 mg/day if taking amlodipine (due to increased rhabdomyolysis risk).
## Monitoring
* **Baseline/Ongoing:** Blood pressure, heart rate, EKG (if on non-dihydropyridines), peripheral edema checks, and liver function tests (if clinically indicated).
## Clinical Pearls
* **Dihydropyridines:** Peripheral edema is dose-dependent and typically does not respond well to diuretics, as it is a result of arterial vasodilation rather than fluid overload.
* **Non-Dihydropyridines:** Use extreme caution when combining with beta-blockers due to additive cardiac depression.
* **Formulations:** ER/SR formulations must not be crushed or chewed to prevent rapid release and toxicity.
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**Disclaimer:** This information is for educational purposes only. Drug dosing, indications, and contraindications may change based on emerging data and local clinical policy. Always verify information with current prescribing data (e.g., package inserts) and your institution’s clinical pharmacy department before prescribing or administering medication.
