NORPACE CR (disopyramide phosphate) · Pfizer
Norpace CR is indicated for the treatment of documented, life-threatening ventricular arrhythmias, such as sustained ventricular tachycardia. Due to its proarrhythmic potential, it is not recommended for less severe arrhythmias, and its use in patients with asymptomatic ventricular premature contractions should be avoided. Therapy must be initiated in a hospital setting. Notably, Norpace CR should not be used when rapid establishment of disopyramide plasma levels is required. Furthermore, antiarrhythmic drugs have not been demonstrated to improve survival in patients with ventricular arrhythmias.
How NORPACE CR Works
Disopyramide phosphate is a Class Ia antiarrhythmic agent. It works by decreasing the rate of diastolic depolarization (Phase 4) in cells with increased automaticity and decreasing the upstroke velocity (Phase 0) of the action potential. It increases the action potential duration (APD) and the effective refractory period in normal cardiac tissues. Additionally, it reduces the disparity in refractoriness between infarcted and normally perfused myocardium. These electrophysiological effects help suppress ectopic foci and stabilize the cardiac rhythm without affecting alpha- or beta-adrenergic receptors.
Details
- Status
- Prescription
- First Approved
- 1982-07-20
- Routes
- ORAL
- Dosage Forms
- CAPSULE, EXTENDED RELEASE
NORPACE CR Approval History
What NORPACE CR Treats
2 indicationsNORPACE CR is approved for 2 conditions since its original approval in 1982. These indications span multiple therapeutic areas including oncology, immunology, and more.
- Ventricular Arrhythmia
- Ventricular Tachycardia
NORPACE CR Boxed Warning
Mortality In the National Heart, Lung and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a long-term, multi-center, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had had a myocardial infarction more than 6 days but less than 2 years previously, an excessive mortality or non-fatal cardiac arrest rate (7.7%) was seen in patients treated with encainide or flecainide compared with that seen in patients assigned to carefu...
Mortality In the National Heart, Lung and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a long-term, multi-center, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had had a myocardial infarction more than 6 days but less than 2 years previously, an excessive mortality or non-fatal cardiac arrest rate (7.7%) was seen in patients treated with encainide or flecainide compared with that seen in patients assigned to carefully matched placebo-treated groups (3.0%). The average duration of treatment with encainide or flecainide in this study was 10 months. The applicability of the CAST results to other populations (e.g., those without recent myocardial infarction) is uncertain. Considering the known proarrhythmic properties of Norpace or Norpace CR and the lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, the use of Norpace or Norpace CR as well as other antiarrhythmic agents should be reserved for patients with life-threatening ventricular arrhythmias.
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Other CDER-designated drugs from the same sponsor (2016–2025).
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Trial Timeline
Full development history with FDA approval milestones
Understanding FDA Approval Types
| Count | Type | What it means |
|---|---|---|
| - | ORIG | Original approval - drug first enters market |
| - | SUPPL - Efficacy | New indication (new disease/condition approved) |
| - | SUPPL - Labeling | Label text changes (warnings, dosing updates) |
| - | SUPPL - Manufacturing | Production changes (new facility) |
| - | SUPPL - Chemistry | Formulation changes (new dosage strength) |
Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.
NORPACE CR FDA Label Details
Indications & Usage
Norpace and Norpace CR are indicated for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia, that, in the judgment of the physician, are life-threatening. Because of the proarrhythmic effects of Norpace and Norpace CR, their use with lesser arrhythmias is generally not recommended. Treatment of patients with asymptomatic ventricular premature contractions should be avoided. Initiation of Norpace or Norpace CR treatment, as with other antiarrhythmic agents used to treat life-threatening arrhythmias, should be carried out in the hospital. Norpace CR sh...
Mortality In the National Heart, Lung and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a long-term, multi-center, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had had a myocardial infarction more than 6 days but less ...
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Data Sources
Data sourced from official FDA and NIH databases. Click links to verify on original sources.