"What are calcium channel blockers (CCBs) and how do they work?
Calcium channel blockers are drugs that block the entry of calcium into the muscle cells of the heart and arteries.
- The entry of calcium is critical for"...
There is no specific antidote for verapamil overdosage; treatment is supportive. Delayed pharmacodynamic consequences may occur with sustained-release formulations, and observe patients for at least 48 hours, preferably under continuous hospital care. Reported effects include hypotension, bradycardia, cardiac conduction defects, arrhythmias, hyperglycemia, and decreased mental status. In addition, there have been literature reports of noncardiogenic pulmonary edema in patients taking large overdoses of verapamil (up to approximately 9 g).
In acute overdosage, consider gastrointestinal decontamination with cathartics and whole bowel irrigation. Calcium, inotropes (i.e., isoproterenol HCl, dopamine HCl, and glucagon), atropine sulfate, vasopressors (i.e., norepinephrine, and epinephrine), and cardiac pacing have been used with variable results to reverse hypotension and myocardial depression. In a few reported cases, overdose with calcium channel blockers that was initially refractory to atropine became more responsive to this treatment when the patients received large doses (close to 1 gram/hour for more than 24 hours) of calcium chloride.
Calcium chloride is preferred to calcium gluconate since it provides 3 times more calcium per volume. Asystole should be handled by the usual measures including cardiopulmonary resuscitation. Verapamil cannot be removed by hemodialysis.
Verapamil is contraindicated in:
- Severe left ventricular dysfunction [see WARNINGS AND PRECAUTIONS].
- Hypotension (less than 90 mm Hg systolic pressure) or cardiogenic shock.
- Sick sinus syndrome (except in patients with a functioning artificial ventricular pacemaker).
- Second- or third-degree AV block (except in patients with a functioning artificial ventricular pacemaker).
- Patients with atrial flutter or atrial fibrillation and an accessory bypass tract (e.g., Wolff-Parkinson-White, Lown-Ganong-Levine syndromes) [see WARNINGS AND PRECAUTIONS].
Last reviewed on RxList: 10/27/2014
This monograph has been modified to include the generic and brand name in many instances.
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