Adults: Individualize dose. Usual: 240mg qam. Elderly/Small People: Initial: 120mg qam. Titrate: If inadequate response with 120mg, increase to 180mg qam, then 240mg qam, then 360mg qam, then 480mg qam based on therapeutic efficacy and safety evaluated approximately 24 hrs after dosing. Switching from Immediate-Release Verapamil: Use same total daily dose. May sprinkle on applesauce. Swallow whole; do not crush or chew.
May cause congestive heart failure (CHF), pulmonary edema, hypotension, asymptomatic 1stdegree AV block, transient bradycardia, and PR interval prolongation. Marked 1st-degree block or progressive development to 2nd/3rd-degree AV block requires dose reduction, or d/c and institution of appropriate therapy. Elevated transaminases with and without concomitant elevation in alkaline phosphatase and bilirubin reported; monitor LFTs periodically. Hepatocellular injury reported. Ventricular response/fibrillation has occurred in patients with paroxysmal and/or chronic A-fib/flutter and a coexisting accessory AV pathway. Sinus bradycardia, pulmonary edema, severe hypotension, 2nd-degree AV block, and sinus arrest reported in patients with hypertrophic cardiomyopathy. Caution with hepatic/renal impairment; monitor for abnormal PR interval prolongation. May decrease neuromuscular transmission in patients with Duchenne's muscular dystrophy and may cause worsening of myasthenia gravis; decrease dose with attenuated neuromuscular transmission.
Constipation, dizziness, headache, lethargy.
May increase levels with CYP3A4 inhibitors (eg, erythromycin, ritonavir) and grapefruit juice. May decrease levels with CYP3A4 inducers (eg, rifampin). Hypotension and bradyarrhythmias reported with telithromycin. May cause myopathy/rhabdomyolysis with HMG-CoA reductase inhibitors that are CYP3A4 substrates; limit dose of simvastatin to 10mg/day or lovastatin to 40mg/day, and may need to lower doses of other CYP3A4 substrates (eg, atorvastatin). Additive negative effects on HR, AV conduction, and contractility with -blockers; avoid with ventricular dysfunction. Asymptomatic bradycardia with atrial pacemaker has been observed with concomitant use of timolol eye drops. Decreased metoprolol clearance reported. Sinus bradycardia resulting in hospitalization and pacemaker insertion has been reported with the use of clonidine; monitor HR. Chronic treatment may increase digoxin levels, which may result in digitalis toxicity. Additive effects with other antihypertensives (eg, vasodilators, ACE inhibitors, diuretics). Excessive reduction in BP with agents that attenuate -adrenergic function (eg, prazosin). Avoid disopyramide within 48 hrs before or 24 hrs after verapamil. Additive negative inotropic effects and AV conduction prolongation with flecainide. Avoid quinidine with hypertrophic cardiomyopathy. May increase carbamazepine, cyclosporine, and alcohol effects. Increased bleeding time with aspirin. Cimetidine may either reduce or not change clearance. May increase sensitivity to neurotoxic effects of lithium; monitor lithium levels. Rifampin may reduce oral bioavailability. May increase clearance with phenobarbital. Caution with inhalation anesthetics. May potentiate neuromuscular blockers; both agents may need dose reduction.
Category C, not for use in nursing.
Absorption: Administration of variable doses resulted in different pharmacokinetic parameters. T
=7-9 hrs. (Immediate-release) Absolute bioavailability (20-35%) Distribution: Plasma protein max
binding (90%); crosses placenta; found in breast milk. Metabolism: Liver (extensive), norverapamil (metabolite). Elimination: Urine (70%, metabolites; 3-4%, unchanged), feces (16%,
Instruct to swallow cap whole; do not crush or chew. Advise that the entire contents of the capsule can be sprinkled onto a spoonful of applesauce; instruct to swallow the applesauce immediately without chewing, and follow with a glass of cool water. Caution that the applesauce should not be hot and should be soft enough to be swallowed without chewing. Instruct to consume the mixture immediately and not store for future use; contents should not be subdivided. Advise to seek medical attention if any adverse reactions occur. Counsel not to breastfeed and to report immediately if pregnant.
Clinical Pearl is a Continuous professional development platform with a precise and concise point of care clinical knowledge search engine and 360-degree learning cycle management platform for all healthcare professionals and organizations.