Calcium%252525252520channel%252525252520blockers

# Calcium Channel Blockers (CCBs) ## Overview CCBs are categorized into two main classes: **Dihydropyridines (DHPs)** (e.g., amlodipine, nifedipine), which primarily cause systemic vasodilation, and **Non-dihydropyridines (Non-DHPs)** (diltiazem, verapamil), which possess negative inotropic and chronotropic properties affecting the AV node. ## Primary Indications * **DHPs:** Hypertension, chronic stable angina, Prinzmetal angina. * **Non-DHPs:** Supraventricular tachyarrhythmias (atrial fibrillation/flutter), hypertension, angina. ## 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 (Non-DHP):** * *Oral (SR/ER):* 120–360 mg/day (varies by formulation). * *IV:* 0.25 mg/kg bolus, followed by 5–15 mg/hr infusion. Consult local institutional protocols for titration. * **Verapamil (Non-DHP):** * *Oral (SR):* 120–480 mg/day. * *IV:* 2.5–5 mg slow IV push over 2–3 minutes. ## Pediatric Dosing *Dosing is highly patient-specific; obtain institutional protocols or specialized pediatric references (e.g., Harriet Lane).* * **Amlodipine:** 0.06–0.3 mg/kg/day PO (Max 10 mg/day). * **Diltiazem:** Oral dosing is not standardized; often initiated at 1.5–3 mg/kg/day divided TID/QID. * *Note:* Avoid Non-DHPs in neonates/infants due to risk of severe refractory hypotension/bradycardia unless directed by a pediatric cardiologist. ## Dose Adjustments * **Hepatic Impairment:** Reduce starting doses for both classes. CCBs undergo extensive hepatic metabolism. * **Renal Impairment:** Generally no dose adjustment required for renal clearance, but monitor for exacerbation of underlying heart failure or peripheral edema. ## Contraindications * **Non-DHPs:** Severe bradycardia, second- or third-degree AV block, sick sinus syndrome (without pacemaker), and HFrEF (systolic heart failure). * **DHPs:** Cardiogenic shock (caution with severe aortic stenosis). * **Hypersensitivity:** Known allergy to the specific agent. ## Adverse Effects * **DHPs:** Peripheral edema (dose-dependent), flushing, headache, reflex tachycardia, gingival hyperplasia. * **Non-DHPs:** Bradycardia, AV block, constipation (especially verapamil), worsening of heart failure, and fatigue. ## Key Drug Interactions * **CYP3A4 Inhibitors:** (e.g., clarithromycin, ketoconazole) significantly increase CCB plasma concentrations (toxicity risk). * **CYP3A4 Inducers:** (e.g., rifampin, phenytoin) decrease CCB efficacy. * **Beta-Blockers:** Enhanced risk of bradycardia and AV block when combined with Non-DHPs. * **Digoxin:** Verapamil and diltiazem increase serum digoxin levels; dose reduction of digoxin may be required. ## Monitoring * **Efficacy:** Blood pressure, heart rate, rhythm (for Non-DHPs). * **Safety:** Baseline and periodic ECG, signs of peripheral edema, symptoms of heart failure (orthopnea, exertional dyspnea). ## Clinical Pearls * **DHP Edema:** Peripheral edema is caused by preferential arteriolar dilation rather than fluid overload; diuretics are typically ineffective for this specific "calcium channel blocker-induced edema." * **Non-DHP Caution:** Never administer IV Non-DHPs with IV beta-blockers without careful monitoring; the additive effect on the AV node can induce cardiac arrest. * **Formulation:** Ensure Nifedipine ER is not crushed or chewed; swallowing efficacy is dependent on the osmotic delivery system. *** **Disclaimer:** This information is for educational purposes only. Drug dosing, contraindications, and interaction profiles can change. Always verify current prescribing information using institutional formularies, clinical decision support tools (e.g., Lexicomp, UpToDate), or a pharmacist before administration.