Calcium%252525252525252525252525252525252525252525252525252525252525252525252525252520channel%252525252525252525252525252525252525252525252525252525252525252525252525252520blockers

# Calcium Channel Blockers ## Overview Calcium channel blockers (CCBs) are a class of drugs that reduce the influx of calcium into cardiac and vascular smooth muscle cells, leading to vasodilation and decreased myocardial contractility and heart rate. They are classified as either dihydropyridines (DHPs) or non-dihydropyridines (non-DHPs). ## Primary Indications * Hypertension * Angina Pectoris (stable, variant) * Supraventricular Tachycardias (rate control) * Raynaud's Phenomenon ## Adult Dosing Dosing varies significantly by agent and indication. **Dihydropyridines (DHPs):** Primarily used for hypertension and angina. * **Amlodipine:** Start at 5 mg once daily. Usual range: 5-10 mg once daily. Maximum: 10 mg once daily. * **Nifedipine (extended-release):** Start at 30 mg once daily. Usual range: 30-90 mg once daily. Maximum: 120 mg once daily. * **Felodipine:** Start at 5 mg once daily. Usual range: 5-10 mg once daily. Maximum: 10 mg once daily. **Non-dihydropyridines (Non-DHPs):** Used for hypertension, angina, and rate control in supraventricular tachycardias. * **Verapamil:** * Hypertension: Start at 80 mg two to three times daily. Usual range: 80-120 mg two to three times daily. Maximum: 480 mg per day. * Angina: Start at 40-80 mg two to three times daily. Usual range: 80-120 mg two to three times daily. Maximum: 480 mg per day. * Supraventricular Tachycardia (IV): 2.5-5 mg IV bolus, may repeat with 5-10 mg IV bolus after 15-30 minutes. Maximum IV dose: 20 mg. * **Diltiazem:** * Hypertension (immediate-release): Start at 30 mg three to four times daily. Usual range: 180-300 mg per day divided into three to four doses. * Hypertension (extended-release): Start at 120-180 mg once daily. Usual range: 120-360 mg once daily. Maximum: 480 mg per day. * Angina: Similar dosing to hypertension. * Supraventricular Tachycardia (IV): 0.25 mg/kg IV bolus, may repeat with 0.35 mg/kg IV bolus after 15 minutes. Continuous infusion: 5-15 mg/hr. ## Pediatric Dosing Pediatric dosing is generally not well-established and requires careful consideration. Specific indications and dosages may vary based on expert consensus and institutional protocols. * **Verapamil:** For supraventricular tachycardia in infants and children, IV doses of 0.1 to 0.3 mg/kg/dose have been used, administered over 1 to 2 minutes. Close monitoring is essential. * **Diltiazem:** Oral dosing for hypertension in children has been reported, but specific guidelines are limited. ## Dose Adjustments * **Hepatic Impairment:** Reduce dose in patients with severe hepatic impairment, especially for non-DHPs. * **Renal Impairment:** Generally no dose adjustment needed for DHPs. For non-DHPs, cautious initiation and titration may be necessary. ## Contraindications * Severe hypotension * Cardiogenic shock * Recent myocardial infarction with pulmonary congestion (specific to non-DHPs) * Sick sinus syndrome or AV block greater than first degree (without a pacemaker) (specific to non-DHPs) * Known hypersensitivity to the drug * Heart failure with reduced ejection fraction (use with caution, especially non-DHPs) ## Adverse Effects * **Common:** Peripheral edema, headache, flushing, dizziness, constipation (especially verapamil), nausea, rash. * **Cardiovascular:** Bradycardia, hypotension, AV block, exacerbation of heart failure. * **Non-DHPs:** Gingival hyperplasia. ## Key Drug Interactions * **Beta-blockers:** Increased risk of bradycardia, AV block, and heart failure due to additive negative chronotropic and inotropic effects. * **Grapefruit Juice:** Can increase plasma concentrations of some CCBs (e.g., amlodipine, felodipine, verapamil). Advise patients to avoid. * **CYP3A4 Inhibitors/Inducers:** Inhibitors (e.g., ketoconazole, erythromycin) can increase CCB levels; inducers (e.g., rifampin) can decrease levels. * **Digoxin:** Non-DHPs can increase digoxin levels. * **Statins:** Certain statins (simvastatin, atorvastatin) may have increased plasma concentrations when used with CCBs. ## Monitoring * Blood pressure and heart rate * Signs of peripheral edema * Electrocardiogram (ECG) for bradycardia or AV block, especially with non-DHPs. * Renal and hepatic function (periodically) * Signs of worsening heart failure. ## Clinical Pearls * DHPs are generally more potent vasodilators and have less effect on cardiac conduction than non-DHPs. * Non-DHPs (verapamil, diltiazem) have significant negative chronotropic and inotropic effects and should be used cautiously or avoided in patients with heart failure or conduction abnormalities. * Constipation is a common side effect of verapamil; dietary fiber and adequate fluid intake may help. * When switching CCBs, a washout period may be necessary. * For rate control in atrial fibrillation with rapid ventricular response, intravenous non-DHPs are preferred over DHPs. *** *Disclaimer: This information is for educational purposes and does not substitute for professional medical advice. Always consult with a qualified healthcare provider and refer to the most current prescribing information for definitive guidance.*