Calcium%2525252520channel%2525252520blockers

# Calcium Channel Blockers (CCBs) ## Overview Calcium channel blockers (CCBs) inhibit the influx of calcium ions into vascular smooth muscle and myocardium. They are classified into two main groups: **Dihydropyridines** (e.g., amlodipine, nifedipine), which primarily cause peripheral vasodilation, and **Non-Dihydropyridines** (e.g., diltiazem, verapamil), which possess greater negative inotropic and chronotropic effects. ## Primary Indications * Hypertension * Chronic stable angina * Supraventricular tachycardias (Rate control—non-DHPs only) * Vasospastic angina (Prinzmetal’s) * Raynaud’s phenomenon (Dihydropyridines) ## Adult Dosing * **Amlodipine (DHP):** 2.5–10 mg PO once daily. Max: 10 mg/day. * **Nifedipine ER (DHP):** 30–90 mg PO once daily. Max: 90 mg/day. * **Diltiazem IR:** 30–90 mg PO TID/QID; **ER (various):** 120–360 mg PO daily. * **Verapamil IR:** 80–160 mg PO TID; **ER:** 180–480 mg PO daily. *Note: Dosing varies significantly by formulation (IR vs. ER); consult specific product monographs to avoid toxicity.* ## Pediatric Dosing * **Amlodipine:** 0.1 mg/kg once daily (max 5 mg) for <6 years; 2.5–5 mg once daily (max 10 mg) for ≥6 years. * **Verapamil/Diltiazem (Off-label):** Used for SVT/arrhythmias; dosing requires pediatric cardiology consultation. Avoid IR products due to erratic absorption and toxicity risks. ## Dose Adjustments * **Hepatic Impairment:** Reduce starting doses for diltiazem and verapamil; significantly lower doses (e.g., 50% reduction) may be required as these agents undergo extensive hepatic metabolism. * **Renal Impairment:** Generally no adjustment required, but monitor for increased sensitivity to hypotensive effects. ## Contraindications * **Non-DHPs:** Severe bradycardia, second- or third-degree AV block (without a pacemaker), decompensated heart failure (HFrEF), and sick sinus syndrome. * **General:** Known hypersensitivity to the agent; hypotension (SBP <90 mmHg). ## Adverse Effects * **Dihydropyridines:** Peripheral edema (dose-dependent), reflex tachycardia, flushing, headache, gingival hyperplasia. * **Non-Dihydropyridines:** Bradycardia, AV block, constipation (especially verapamil), exacerbation of HFrEF, dizziness. ## Key Drug Interactions * **CYP3A4 Inhibitors/Inducers:** Strong inhibitors (e.g., clarithromycin, ketoconazole) significantly increase CCB levels; inducers (e.g., rifampin, phenytoin) decrease levels. * **Beta-blockers:** Additive negative chronotropic/inotropic effects (caution with non-DHPs). * **Statins:** Diltiazem and verapamil inhibit CYP3A4, increasing concentrations of simvastatin and lovastatin (limit doses significantly). * **Digoxin:** Verapamil and diltiazem increase serum digoxin levels. ## Monitoring * **Baseline/Routine:** Blood pressure, heart rate, EKG (if non-DHP), renal/hepatic function. * **Symptomatic:** Monitor for signs of peripheral edema, signs of heart failure (dyspnea, weight gain), and symptoms of bradycardia. ## Clinical Pearls * **Never substitute:** Diltiazem and verapamil extended-release formulations are not always bioequivalent; prescribe by brand if indicated by local safety protocols. * **Edema management:** Peripheral edema from amlodipine is often resistant to diuretics; adding an ACE inhibitor or ARB may mitigate the effect by normalizing capillary hydrostatic pressure. * **Avoid Sublingual Nifedipine:** Immediate-release nifedipine sublingual/punctured capsule is contraindicated due to risk of precipitous hypotension, myocardial infarction, and death. *** **Educational Disclaimer:** This information is for educational purposes for healthcare professionals. Clinical practice guidelines and local protocols vary. Verify all dosing, compatibility, and safety information with current institutional resources and official FDA-approved prescribing information before administration.