Calcium%2525252525252525252525252520channel%2525252525252525252525252520blockers

## Overview Calcium channel blockers (CCBs) are a class of drugs that reduce the influx of calcium ions into cardiac and vascular smooth muscle cells. They are broadly categorized into dihydropyridines (DHPs) and non-dihydropyridines (non-DHPs). DHPs primarily affect vascular smooth muscle, while non-DHPs affect both vascular and cardiac muscle. ## Primary Indications * Hypertension * Angina pectoris (stable and vasospastic) * Certain arrhythmias (e.g., supraventricular tachycardia - non-DHPs) * Raynaud's phenomenon ## Adult Dosing Dosing is highly dependent on the specific agent, formulation (immediate-release vs. extended-release), and indication. **Dihydropyridines (e.g., amlodipine, nifedipine, felodipine):** * **Amlodipine:** Start at 5 mg orally once daily, may increase to 10 mg orally once daily. Max: 10 mg/day. * **Nifedipine ER:** Start at 30 mg orally once daily, titrate gradually to 60-90 mg orally once daily. Max: 120 mg/day. * **Felodipine ER:** Start at 5 mg orally once daily, titrate to 10 mg orally once daily. Max: 10 mg/day. **Non-Dihydropyridines (e.g., verapamil, diltiazem):** * **Verapamil IR:** 80-120 mg orally 2-3 times daily. Max: 160 mg/dose or 480 mg/day. * **Verapamil ER:** 180 mg orally once daily, may increase to 120-240 mg orally once daily or twice daily. Max: 480 mg/day. * **Diltiazem IR:** 30-60 mg orally 3-4 times daily. Max: 360 mg/day. * **Diltiazem ER (various formulations):** Doses vary significantly by formulation. Common starting doses range from 60 mg to 180 mg once or twice daily. Max doses are formulation-dependent and can range from 240 mg to 480 mg daily. *Specific dosing regimens for specific indications and formulations should be guided by product labeling and local protocols.* ## Pediatric Dosing Established pediatric dosing for CCBs is limited and often off-label. Dosing may be initiated at lower doses and titrated cautiously. * **Amlodipine:** Limited data for hypertension in children ≥ 6 years. Typical starting dose: 2.5 mg/day. May titrate to 5 mg/day. Max: 5 mg/day. * **Verapamil:** Used for supraventricular tachycardia in infants and children. IV doses are typically 0.1-0.25 mg/kg/dose. Oral doses and chronic use data are less well-established and require expert consultation. * **Diltiazem:** Used for supraventricular tachycardia in infants and children. IV doses are typically 0.25 mg/kg/dose. Oral doses and chronic use data are less well-established and require expert consultation. *Consult pediatric-specific drug references or specialists for detailed pediatric dosing recommendations.* ## Dose Adjustments * **Hepatic Impairment:** Reduce dose and titrate cautiously, particularly with non-DHPs, as they undergo significant hepatic metabolism. * **Elderly:** May be more sensitive to hypotensive effects and bradycardia; initiate at lower doses. * **Renal Impairment:** Generally, dose adjustments are not required for renal impairment, but caution is advised, especially with non-DHPs. ## Contraindications * Severe hypotension * Cardiogenic shock * Acute myocardial infarction (most DHPs unless specifically indicated, e.g., amlodipine for ongoing angina) * Severe left ventricular dysfunction (especially non-DHPs) * Heart block (2nd or 3rd degree) or sick sinus syndrome without a pacemaker (especially non-DHPs) * Concomitant use of beta-blockers (IV) or disopyramide (non-DHPs) due to additive negative chronotropic and inotropic effects. * Known hypersensitivity to the drug. ## Adverse Effects * **Common:** Peripheral edema (DHPs), headache, flushing, dizziness, constipation (verapamil), nausea. * **Cardiovascular:** Hypotension, bradycardia, AV block, heart failure exacerbation, syncope, palpitations. * **Non-cardiac:** Gingival hyperplasia (prolonged use), rash, hypersensitivity reactions. ## Key Drug Interactions * **Beta-blockers:** Additive myocardial depressant effects (negative chronotropy and inotropy), increasing risk of bradycardia and heart block. Non-DHPs have a more significant interaction. * **CYP3A4 Inhibitors (e.g., grapefruit juice, azole antifungals, macrolide antibiotics):** Increase serum concentrations of many CCBs (especially DHPs and non-DHPs), increasing risk of hypotension and other adverse effects. * **CYP3A4 Inducers (e.g., rifampin, carbamazepine, phenytoin):** Decrease serum concentrations of many CCBs, potentially leading to reduced efficacy. * **Digoxin:** Non-DHPs can increase digoxin levels. * **Statins (simvastatin, atorvastatin):** CCBs can increase statin concentrations, particularly simvastatin and atorvastatin, increasing risk of myopathy. Avoid high-dose simvastatin with CCBs. * **Amiodarone:** Increased risk of bradycardia and AV block. ## Monitoring * Blood pressure (supine and standing) * Heart rate * Electrocardiogram (ECG), especially when initiating non-DHPs or in patients with pre-existing conduction abnormalities. * Signs and symptoms of heart failure. * Renal function and electrolytes periodically. * Liver function tests periodically, especially in patients with hepatic impairment. ## Clinical Pearls * Dihydropyridines are generally preferred for hypertension due to their potent vasodilatory effects and lower risk of cardiac conduction disturbances. * Non-dihydropyridines (verapamil, diltiazem) are useful for rate control in atrial fibrillation and for angina, but carry a higher risk of bradycardia and AV block. * Extended-release formulations are preferred for chronic management of hypertension and angina to provide consistent plasma concentrations and reduce dosing frequency. * Peripheral edema with DHPs is dose-related and can be managed with diuretics or by switching to a non-DHP (if appropriate). * Gingival hyperplasia is a rare but possible side effect, particularly with prolonged use of DHPs; emphasize good oral hygiene. * Avoid grapefruit juice with most CCBs. * In patients with concomitant heart failure, CCBs should be used with extreme caution; amlodipine is generally considered the safest CCB in this population. *** *This information is intended for clinical pharmacists and healthcare professionals. It is not exhaustive and does not replace the need to consult official prescribing information, current guidelines, and individual patient factors. Always verify current prescribing information before making clinical decisions.*