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# Calcium Channel Blockers ## Overview Calcium channel blockers (CCBs) are a class of medications that inhibit the influx of calcium ions into vascular smooth muscle and cardiac muscle, leading to vasodilation and/or decreased myocardial contractility and heart rate. They are classified into dihydropyridines (e.g., amlodipine, nifedipine) and non-dihydropyridines (e.g., verapamil, diltiazem). ## Primary Indications * Hypertension * Angina pectoris (stable and vasospastic) * Certain arrhythmias (supraventricular tachycardias, rate control for atrial fibrillation/flutter) * Raynaud's phenomenon ## Adult Dosing Dosing varies significantly based on the specific agent and indication. * **Dihydropyridines:** * Amlodipine: 2.5-10 mg once daily. Max: 10 mg daily. * Nifedipine (extended-release): 30-90 mg once daily. Max: 120 mg daily. * Nicardipine (infusion): Typically 5-15 mcg/kg/min, titrate as needed. * **Non-dihydropyridines:** * Diltiazem (extended-release): 180-360 mg once daily. Max: 360 mg daily. * Verapamil (extended-release): 180-480 mg once daily or divided into two doses. Max: 480 mg daily. * Verapamil (IV): 2.5-5 mg bolus, may repeat with 5-10 mg in 15-30 minutes. *Exact dosing depends on local protocol and patient-specific factors.* ## Pediatric Dosing Limited data for many CCBs. Dosing is often weight-based and requires careful titration, typically initiated at lower doses than adults. Consultation with a pediatric specialist is often recommended. * **Amlodipine:** 0.1-0.6 mg/kg once daily (usual maximum 5-10 mg daily). * **Diltiazem:** 0.5-2 mg/kg/day divided every 6-8 hours (IV), or 3-5 mg/kg/day divided every 6-8 hours (PO). * **Verapamil:** 0.1-4 mg/kg/day divided every 6-8 hours (PO), or 0.1-0.3 mg/kg/dose IV. *Specific pediatric dosing requires careful consideration and is often guided by specialty centers and drug-specific guidelines.* ## Dose Adjustments * **Hepatic Impairment:** Reduce initial dose and titrate cautiously, as CCBs are extensively metabolized by the liver. * **Renal Impairment:** Generally no dose adjustment is needed for hemodynamically stable patients. However, monitor for adverse effects. ## Contraindications * Severe hypotension * Cardiogenic shock (with exceptions for specific agents and indications) * Recent myocardial infarction (exceptions may apply for specific agents) * Sick sinus syndrome or high-grade AV block without a pacemaker (non-dihydropyridines) * Known hypersensitivity to the drug ## Adverse Effects * **Dihydropyridines:** Peripheral edema, headache, flushing, dizziness, reflex tachycardia. * **Non-dihydropyridines:** Bradycardia, AV block, constipation (especially verapamil), nausea, dizziness, headache. * **Both:** Hypotension, gingival hyperplasia (long-term use). ## Key Drug Interactions * **Beta-blockers:** Additive effects on bradycardia and AV conduction. * **Grapefruit Juice:** Increases levels of some CCBs (e.g., amlodipine, nifedipine), increasing risk of hypotension. * **CYP3A4 Inhibitors/Inducers:** Can alter CCB metabolism (e.g., azole antifungals, macrolides, rifampin). * **Digoxin:** Non-dihydropyridines can increase digoxin levels. * **Statins:** Increased risk of myopathy with some statins (e.g., simvastatin, atorvastatin) when co-administered with certain CCBs. ## Monitoring * Blood pressure (including postural changes) * Heart rate and rhythm * Signs and symptoms of heart failure * Electrolytes (especially with diuretic co-administration) * Renal and hepatic function ## Clinical Pearls * Dihydropyridines are generally preferred for vasodilation and hypertension, while non-dihydropyridines are useful for rate control in supraventricular tachycardias and atrial fibrillation due to their negative chronotropic and inotropic effects. * Non-dihydropyridines should be used with caution in patients with reduced left ventricular function. * Avoid short-acting nifedipine for hypertension due to risk of reflex tachycardia and precipitous BP drops. * Peripheral edema with dihydropyridines is dose-dependent and can sometimes be managed with lower doses or addition of an ACE inhibitor/ARB. *** **Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant guidelines for complete details before making any treatment decisions. Dosing and recommendations can vary based on individual patient factors and local institutional protocols.