VERAPAMIL SUMMARY
VERAPAMIL HYDROCHLORIDE
Extended-release Capsules
mg, 180 mg and 240 mg
Verapamil HCl is a calcium antagonist or slow channel inhibitor.
Intravenous Verapamil HCI is indicated for the following:
- Rapid conversion to sinus rhythm of paroxysmal supraventricular tachycardias, including those associated with accessory bypass tracts (Wolff-Parkinson-White [W-P-W] and Lown-Ganong-Levine [L-G-L] syndromes). When clinically advisable, appropriate vagal maneuvers (e.g., Valsalva maneuver) should be attempted prior to verapamil hydrochloride administration.
- Temporary control of rapid ventricular rate in atrial flutter or atrial fibrillation except when the atrial flutter and/or atrial fibrillation are associated with accessory bypass tracts (Wolff-Parkinson-White [W-P-W] and Lown-Ganong-Levine [L-G-L] syndromes).
In controlled studies in the United States, about 60% of patients with supraventricular tachycardia converted to normal sinus rhythm within 10 minutes after intravenous verapamil. Uncontrolled studies reported in the world literature describe a conversion rate of about 80%. About 70% of patients with atrial flutter and/or fibrillation with a fast ventricular rate respond with a decrease in ventricular rate of at least 20%. Conversion of atrial flutter or fibrillation to sinus rhythm is uncommon (about 10%) after verapamil and may reflect the spontaneous conversion rate, since the conversion rate after placebo was similar. Slowing of the ventricular rate in patients with atrial fibrillation/flutter lasts 30 to 60 minutes after a single injection.
Because a small fraction (<1%) of patients treated with verapamil respond with life-threatening adverse responses (rapid ventricular rate In atrial flutter/fibrillation and an accessory bypass tract, marked hypotension, or extreme bradycardia/asystole - see Contraindications and Warnings), the initial use of intravenous verapamil should, if possible, be in a treatment setting with monitoring and resuscitation facilities, including DC-cardioversion capability (see Suggested Treatment of Acute Cardiovascular Adverse Reactions). As familiarity with the patient's response is gained, use in an office setting may be acceptable.
Cardioversion has been used safely and effectively after intravenous verapamil.
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