Calcium%2525252525252520channel%2525252525252520blockers

# Calcium Channel Blockers (CCBs) ## Overview CCBs inhibit the influx of calcium ions into vascular smooth muscle and cardiac muscle cells. They are classified into two main groups: * **Dihydropyridines (DHPs):** Selectively act as potent vasodilators (e.g., amlodipine, nifedipine). * **Non-Dihydropyridines (Non-DHPs):** Have significant negative chronotropic and inotropic effects (e.g., diltiazem, verapamil). ## Primary Indications * **Hypertension (DHP/Non-DHP):** First-line therapy for most patients. * **Angina Pectoris (DHP/Non-DHP):** Chronic stable or vasospastic. * **Supraventricular Tachycardias (Non-DHP only):** Rate control for AFib/AFlutter. ## 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 ER (Non-DHP):** 120–360 mg PO once daily. Max: 360 mg/day (or 480 mg depending on formulation). * **Verapamil ER (Non-DHP):** 120–480 mg PO daily (divided or ER). Max: 480 mg/day. ## Pediatric Dosing *Note: Strict weight-based dosing is required; consult local pediatric formulary (e.g., Lexicomp/Harriet Lane).* * **Amlodipine:** 0.06–0.1 mg/kg PO once daily. Max: 5–10 mg/day depending on age. * **Diltiazem:** 1.5–3.5 mg/kg/day PO divided tid/qid. * **Verapamil:** 4–8 mg/kg/day PO divided tid/qid. ## Dose Adjustments * **Hepatic Impairment:** Reduce starting doses for diltiazem and verapamil; these undergo extensive hepatic metabolism. * **Renal Impairment:** Generally no adjustment required; however, monitor for hypotension and peripheral edema. ## Contraindications * **Non-DHPs:** Severe bradycardia, second- or third-degree AV block (without a pacemaker), sick sinus syndrome, and HFrEF (systolic heart failure). * **General:** Known hypersensitivity to the specific agent. ## Adverse Effects * **DHPs:** Peripheral edema, flushing, headache, gingival hyperplasia, reflex tachycardia. * **Non-DHPs:** Bradycardia, AV block, constipation (especially verapamil), constipation, worsen heart failure symptoms. ## Key Drug Interactions * **CYP3A4 Inhibitors/Inducers:** Levels of CCBs may significantly increase (e.g., clarithromycin, azoles) or decrease (e.g., rifampin). * **Beta-Blockers:** Increased risk of AV block and profound bradycardia (additive effects with Non-DHPs). * **Statins:** Diltiazem and verapamil increase levels of simvastatin and lovastatin; limit simvastatin dose to 10 mg/day. * **Digoxin:** Verapamil and diltiazem can increase serum digoxin concentration. ## Monitoring * **Blood Pressure and Heart Rate:** Assess at every visit or during titration. * **EKG:** Required when initiating or titrating Non-DHPs (PR interval assessment). * **Edema:** Monitor lower extremities, especially with DHPs. * **Symptoms of Heart Failure:** Monitor for weight gain, orthopnea, or dyspnea. ## Clinical Pearls * **Do not use immediate-release nifedipine** for hypertensive urgency/emergency due to risk of unpredictable hypotension and reflex tachycardia. * **Diltiazem/Verapamil** should generally be avoided in patients with HFrEF due to negative inotropic effects. * **Gingival hyperplasia** is a well-documented risk with long-term DHP use; emphasize oral hygiene. * Always check the specific extended-release formulation, as conversion between brands is not always 1:1. *** **Disclaimer:** This information is for educational purposes and does not replace professional clinical judgment. Always verify dosages, contraindications, and drug interactions using current, site-specific hospital protocols and evidence-based drug databases (e.g., Lexicomp, Micromedex) before prescribing or administering medications.