Verapamil
Calcium Antagonist · Calcium antagonist
Indications
Tab: Treatment & prophylaxis of angina pectoris, supraventricular tachycardia of reciprocating type associated with Wolff-Parkinson-White syndrome. Mild to moderate hypertension. Inj: Supraventricular arrhythmias.
Dosage
Adults: ORAL: Angina: Vasospastic/Unstable/Chronic Stable: Usual: 80-120 mg three times daily. Titrate: Increase by once daily or once weekly intervals. Arrhythmia: A-Fib (Digitalized): Usual: 240-320 mg/day divided in three or four doses daily. PSVT Prophylaxis (Non-Digitalized): 240-480 mg/day divided in three or four doses daily. Max: 480 mg/day. Hypertension: Initial: 80 mg three times daily. Usual: 360-480 mg/day. SR Cap/Tab: Initial: 180 mg every morning. Titrate: Increase to 240 mg every morning, then 180 mg twice daily; or 240 mg + 120 mg every evening, then 240 mg every 12 hr. Adults: INJECTION: SVT: IV: 2.5-5 mg (over 2 min); 2nd dose of 5-10 mg (~0.15 mg/kg) may be given 15-30 min after the initial dose if patient tolerates, but does not respond to initial dose; Max total dose: 20 mg. Children: Modified release preparation not licensed for use in children. Hypertension,…
Administration
For IV use only. Give as a slow IV injection over at least a 2 min time period under continuous ECG and blood pressure monitoring. Disopyramide or flecainide should not be given within 48 hours before or 24 hours after verapamil because additive negative inotropic effects can result. Compatibility: Stable in Ringer’s solution, D5W, NS. For stability reason, this product is not recommended for dilution with sodium lactate injection in polyvinyl chloride bags. Verapamil injection will precipitate in any solution with a pH above 6. Stability: Store at controlled room temperature 15°C-30°C (59°F-86°F). Protect from light.
Adverse Effects
Constipation. Rarely flushes, dizziness, vomiting, fatigue, ankle oedema, GI upset, paraesthesia, extrapyramidal syndrome, skin reactions, tremor, vertigo, tinnitus, muscle weakness, myalgia, arthralgia, bradycardia, asystole, tachycardia, headaches, nausea, allergies, reversible liver function impairment, gynaecomastia, gingival hyperplasia. Decreased heart rate, hypotension, decreased myocardial contractability, 2nd or 3rd degree AV block.
Risk Factor (Pregnancy/Lactation)
Pregnancy: Risk cannot be ruled out. Lactation: Caution advised or effect undetermined. Contraindications: Cardiogenic shock. 2nd or 3rd degree AV block, SA block. Severe bradycardia, sick sinus syndrome. Uncompensated heart failure. Acute phase of MI. Hypotension of less than 90 mmHg systolic. Precautions: 1st degree AV block, poor cardiac reserve should be controlled with digitalis and diuretics. Bradycardia, acute MI, renal or hepatic impairment, conduction disturbances. Atrial flutter/fibrillation with an accessory pathway. Hepatic or renal impairment. Myasthaenia gravis.
Interactions
Beta-blockers, digoxin or antiarrhythmics, cyclosporin, theophylline, muscle relaxants, carbamazepine, rifampicin, lithium, phenobarbitone, phenytoin, cimetidine, inhaled anaesthetics, alcohol, antihypertensives, grapefruit juice, CYP3A4 inhibitors or inducers (e.g., ketoconazole, erythromycin, ritonavir), immunosuppressants, statins, St John's wort, dantrolene, aspirin, alpha blockers, imipramine, glibenclamide, other antihypertensives, doxorubicin, buspirone, midazolam, colchicine, almotriptan, sulfinpyrazone, ivabradine, dabigatran.
Advice to Patient
Take with meals. Do not chew or crush extended release forms, swallow whole. Contact prescriber if there is chest pain, palpitations, irregular heartbeat, unusual cough, difficulty in breathing, swelling of feet or ankles, muscle weakness, muscle tremors, confusion, skin rash or irritation. Avoid grapefruit juice, alcohol and caffeine during therapy. Check pulse daily and inform prescriber if it falls below 50 beats per minute.
Pharmacokinetics
Note: Lean body wt affects verapamil pharmacokinetics inversely. Onset of action: Peak effect: Oral: Immediate release: 1-2 hrs. IV bolus: 3-5 min. Duration: Oral: Immediate release tabs: 6-8 hrs. IV: 0.5-6 hrs. Absorption: Oral: Well absorbed (>90%). Metabolism: Hepatic (extensive first-pass effect). Bioavailability: Oral: 20%-35%. Half-life elimination: Inj: Terminal: 2-5 hrs. Oral: Immediate release: Single dose: 2.8-7.4 hrs. Multiple doses: 4.5-12 hrs. Extended release: Approx. 12 hrs. Severe hepatic impairment: 14-16 hrs. Time to peak, serum: Oral: Immediate release: 1-2 hrs. Excretion: Urine (approx. 74%). Faeces (=16%).
Brands with this active ingredient
Compiled by Healify Pharmacy from published drug references. How we compile it →
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