Calcium%25252525252520channel%25252525252520blockers

# Calcium Channel Blockers (CCBs) ## Overview CCBs are categorized into two main classes: **Dihydropyridines (DHP)** (e.g., amlodipine, nifedipine), which primarily cause peripheral vasodilation, and **Non-dihydropyridines (Non-DHP)** (e.g., diltiazem, verapamil), which have significant negative chronotropic and dromotropic effects on the heart. ## Primary Indications * **Hypertension** (All CCBs) * **Angina Pectoris** (All CCBs) * **Supraventricular Tachycardias / Rate Control** (Non-DHPs) * **Raynaud's Phenomenon** (DHPs) ## Adult Dosing * **Amlodipine:** 2.5–10 mg PO daily. Max: 10 mg/day. * **Nifedipine ER:** 30–90 mg PO daily. Max: 90 mg/day. * **Diltiazem (Extended Release):** 120–360 mg PO daily. Max: 480 mg/day. * **Verapamil (Extended Release):** 120–480 mg PO daily (divided BID or daily depending on formulation). Max: 480 mg/day. ## Pediatric Dosing *Dosing varies significantly by age, weight, and indication. Always consult weight-based institutional protocols (e.g., Harriet Lane).* * **Amlodipine:** 0.1 mg/kg/day (up to 5 mg) initially. Max: 10 mg/day. * **Diltiazem:** Often used for rate control; dosing requires expert titration (typically 1.5–3.5 mg/kg/day divided TID/QID for IR). ## Dose Adjustments * **Hepatic Impairment:** Reduce starting doses for diltiazem, verapamil, and nifedipine, as these undergo extensive hepatic metabolism. * **Renal Impairment:** Generally no dose adjustment required, but use caution due to potential for peripheral edema. ## Contraindications * **Severe Hypotension.** * **Non-DHPs:** HFrEF (reduced ejection fraction), 2nd or 3rd-degree heart block (without a pacemaker), and sick sinus syndrome. * **Nifedipine IR:** Avoid in hypertensive emergencies or routine hypertension due to risk of unpredictable, profound hypotension/reflex tachycardia. ## Adverse Effects * **DHPs:** Peripheral edema (dose-dependent), reflex tachycardia, flushing, headache, gingival hyperplasia. * **Non-DHPs:** Bradycardia, AV block, constipation (especially verapamil), HF exacerbation. ## Key Drug Interactions * **CYP3A4 Inhibitors/Inducers:** CCBs are CYP3A4 substrates; toxicity may occur with clarithromycin, azoles, or grapefruit juice. * **Beta-Blockers:** Increased risk of severe bradycardia and heart block (additive effect with non-DHPs). * **Statins:** Simvastatin/lovastatin levels increased by diltiazem/verapamil (limit simvastatin dose to 10 mg/day). * **Digoxin:** Verapamil and diltiazem significantly increase serum digoxin levels. ## Monitoring * **All:** Baseline and periodic blood pressure and heart rate. * **Non-DHPs:** ECG (PR interval prolongation) and signs of heart failure (weight gain, dyspnea). * **DHPs:** Assess for dependent edema. ## Clinical Pearls * **DHP vs. Non-DHP:** Do not use nondihydropyridines for hypertension in patients with systolic heart failure. * **Peripheral Edema:** DHP-induced edema is due to precapillary dilation, not fluid overload. Diuretics are generally ineffective; adding an ACEI/ARB or reducing the DHP dose is preferred. * **Formulations:** Never crush or chew extended or sustained-release formulations. *** **Educational Disclaimer:** This information is for educational purposes and does not constitute medical advice. Always verify current prescribing information, institutional protocols, and patient-specific factors via reliable clinical databases (e.g., Lexicomp, UpToDate) before prescribing or administering medication.