Calcium%252525252525252525252520channel%252525252525252525252520blockers

# Calcium Channel Blockers (CCBs) ## Overview CCBs inhibit the influx of calcium ions into vascular smooth muscle and cardiac muscle via L-type calcium channels. Divided into two main classes: **Dihydropyridines** (e.g., amlodipine, nifedipine; primarily vasodilators) and **Non-dihydropyridines** (e.g., diltiazem, verapamil; negative inotropic/chronotropic effects). ## Primary Indications * Hypertension * Angina pectoris * Supraventricular tachyarrhythmias (non-DHPs only) * Raynaud's phenomenon (dihydropyridines) ## Adult Dosing * **Amlodipine:** Hypertension: 2.5–10 mg PO once daily (Max: 10 mg/day). * **Diltiazem (ER):** Hypertension: 180–360 mg PO once daily; Arrhythmia (IV): 0.25 mg/kg bolus, followed by 5–15 mg/hr infusion. * **Verapamil (ER):** Hypertension: 120–480 mg PO daily; Angina: 80–120 mg TID. * **Nifedipine (ER):** Hypertension/Angina: 30–90 mg PO once daily (Max: 120 mg/day). ## Pediatric Dosing *Dosing is highly protocol-dependent; verify with individual institution guidelines.* * **Amlodipine:** 0.1 mg/kg/day PO (Max: 5 mg daily for age 6–17 years). * **Diltiazem:** Not commonly used as first-line. Hypertension: 1–2 mg/kg/day divided TID (Immediate release). ## Dose Adjustments * **Hepatic Impairment:** Reduce starting doses for diltiazem, verapamil, and amlodipine as they are extensively metabolized by the liver. * **Renal Impairment:** Generally no adjustment required for CCBs; however, monitor for fluid retention. ## Contraindications * **Non-DHPs (Diltiazem/Verapamil):** Acute heart failure (HFrEF), second or third-degree AV block, sick sinus syndrome (unless pacemaker present), severe hypotension. * **Dihydropyridines:** Severe aortic stenosis (may worsen cardiac output). ## Adverse Effects * **Peripheral Edema:** Most common with dihydropyridines (dose-dependent). * **Non-DHPs:** Bradycardia, AV block, worsening of heart failure, constipation (especially verapamil). * **General:** Flushing, dizziness, hypotension, headache. ## Key Drug Interactions * **CYP3A4 Inhibitors/Inducers:** Levels significantly increased by clarithromycin, ketoconazole, and grapefruit juice; decreased by rifampin. * **Beta-blockers:** Increased risk of additive bradycardia and AV block when used with non-DHPs. * **Statins:** Diltiazem and verapamil inhibit CYP3A4, increasing serum concentrations of atorvastatin and simvastatin; limit simvastatin dose. ## Monitoring * Blood pressure and heart rate (daily during titration). * Cardiac rhythm (ECG) for initiation of non-DHP IV formulations. * Signs of symptomatic heart failure (weight gain, dyspnea). ## Clinical Pearls * **Dihydropyridines vs. Non-Dihydropyridines:** Do not combine non-DHPs with beta-blockers without specialist oversight due to potentially fatal heart block or severe myocardial suppression. * **Edema:** Peripheral edema caused by dihydropyridines is vasodilatory and typically unresponsive to diuretics. Consider adding an ACE inhibitor/ARB or switching agents. * **Immediate-release nifedipine:** Avoid using for acute hypertension ("sublingual nifedipine") due to risk of unpredictable, severe hypotension and reflex tachycardia. *** *Disclaimer: This information is for educational purposes only and does not replace professional clinical judgment. Dosing and clinical protocols vary by institution; always verify current prescribing information, package inserts, and local practice guidelines before prescribing or administering medication.*