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| __NOTOC__
| | #REDIRECT [[Disopyramide#Warnings]] |
| {{Disopyramide}}
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| {{CMG}}; {{AE}} {{SS}}
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| ==Warnings and Precautions==
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| {|
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| |[[File:Disopyramide01.jpg|thumb|800px]]
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| ===Negative Inotropic Properties===
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| ====Heart Failure/Hypotension====
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| Norpace or Norpace CR may cause or worsen [[congestive heart failure]] or produce severe [[hypotension]]as a consequence of its negative inotropic properties. [[hypotension]]has been observed primarily in patients with primary cardiomyopathy or inadequately compensated [[congestive heart failure]]. Norpace or Norpace CR should not be used in patients with uncompensated or marginally compensated [[congestive heart failure]] or [[hypotension]]unless the [[congestive heart failure]] or [[hypotension]]is secondary to cardiac [[arrhythmia]]. Patients with a history of heart failure may be treated with Norpace or Norpace CR, but careful attention must be given to the maintenance of cardiac function, including optimal digitalization. If [[hypotension]]occurs or [[congestive heart failure]] worsens, Norpace or Norpace CR should be discontinued and, if necessary, restarted at a lower dosage only after adequate cardiac compensation has been established.
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| ====QRS Widening====
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| Although it is unusual, significant widening (greater than 25%) of the QRS complex may occur during Norpace or Norpace CR administration; in such cases Norpace or Norpace CR should be discontinued.
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| ====Q-T Prolongation====
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| As with other Type 1 antiarrhythmic drugs, prolongation of the Q-T interval (corrected) and worsening of the [[arrhythmia]], including ventricular [[tachycardia]] and ventricular fibrillation, may occur. Patients who have evidenced prolongation of the Q-T interval in response to [[quinidine]] may be at particular risk. As with other Type 1A antiarrhythmics, disopyramide phosphate has been associated with torsade de pointes.
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| If a Q-T prolongation of greater than 25% is observed and if ectopy continues, the patient should be monitored closely, and consideration given to discontinuing Norpace or Norpace CR.
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| ====Hypoglycemia====
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| In rare instances significant lowering of blood-glucose values has been reported during Norpace administration. The physician should be alert to this possibility, especially in patients with [[congestive heart failure]], chronic malnutrition, hepatic, renal or other diseases, or drugs (e.g., beta-adrenoceptor blockers, alcohol) which could compromise preservation of the normal glucoregulatory mechanisms in the absence of food. In these patients the blood-glucose levels should be carefully followed.
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| ====Concomitant Antiarrhythmic Therapy====
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| The concomitant use of Norpace or Norpace CR with other Type 1A antiarrhythmic agents (such as quinidine or procainamide), Type 1C antiarrhythmics (such as [[encainide]], [[flecainide]] or [[propafenone]]), and/or [[propranolol]] should be reserved for patients with life-threatening [[arrhythmia]]s who are demonstrably unresponsive to single-agent antiarrhythmic therapy. Such use may produce serious negative inotropic effects, or may excessively prolong conduction. This should be considered particularly in patients with any degree of cardiac decompensation or those with a prior history thereof. Patients receiving more than one antiarrhythmic drug must be carefully monitored.
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| ====Heart Block====
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| If first-degree heart block develops in a patient receiving Norpace or Norpace CR, the dosage should be reduced. If the block persists despite reduction of dosage, continuation of the drug must depend upon weighing the benefit being obtained against the risk of higher degrees of heart block. Development of second- or third-degree AV block or unifascicular, bifascicular, or trifascicular block requires discontinuation of Norpace or Norpace CR therapy, unless the ventricular rate is adequately controlled by a temporary or implanted ventricular pacemaker.
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| ====Anticholinergic Activity====
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| Because of its anticholinergic activity, disopyramide phosphate should not be used in patients with [[glaucoma]], [[myasthenia gravis]], or urinary retention unless adequate overriding measures are taken; these consist of the topical application of potent miotics (e.g., [[pilocarpine]]) for patients with [[glaucoma]], and catheter drainage or operative relief for patients with urinary retention. Urinary retention may occur in patients of either sex as a consequence of Norpace or Norpace CR administration, but males with benign prostatic hypertrophy are at particular risk. In patients with a family history of [[glaucoma]], intraocular pressure should be measured before initiating Norpace or Norpace CR therapy. Disopyramide phosphate should be used with special care in patients with myasthenia gravis since its anticholinergic properties could precipitate a myasthenic crisis in such patients.
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| ===PRECAUTIONS===
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| ====General====
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| =====Atrial Tachyarrhythmias=====
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| Patients with atrial flutter or fibrillation should be digitalized prior to Norpace or Norpace CR administration to ensure that drug-induced enhancement of AV conduction does not result in an increase of ventricular rate beyond physiologically acceptable limits.
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| =====Conduction Abnormalities=====
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| Care should be taken when prescribing Norpace or Norpace CR for patients with sick sinus syndrome ([[bradycardia-tachycardia syndrome]]), Wolff-Parkinson-White syndrome (WPW), or bundle branch block. The effect of disopyramide phosphate in these conditions is uncertain at present.
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| =====Cardiomyopathy=====
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| Patients with [[myocarditis]] or other cardiomyopathy may develop significant [[hypotension]]in response to the usual dosage of disopyramide phosphate, probably due to cardiodepressant mechanisms. Therefore, a loading dose of Norpace should not be given to such patients, and initial dosage and subsequent dosage adjustments should be made under close supervision (see Dosage and Administration).
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| =====Renal Impairment=====
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| More than 50% of disopyramide is excreted in the urine unchanged. Therefore Norpace dosage should be reduced in patients with impaired renal function (see Dosage and Administration). The electrocardiogram should be carefully monitored for prolongation of PR interval, evidence of QRS widening, or other signs of overdosage (seeOverdosage).
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| Norpace CR is not recommended for patients with severe renal insufficiency (creatinine clearance 40 ml/min or less).
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| =====Hepatic Impairment=====
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| Hepatic impairment also causes an increase in the plasma half-life of disopyramide. Dosage should be reduced for patients with such impairment. The electrocardiogram should be carefully monitored for signs of overdosage (see Overdosage).
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| Patients with cardiac dysfunction have a higher potential for hepatic impairment; this should be considered when administering Norpace or Norpace CR.
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| =====Potassium Imbalance=====
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| Antiarrhythmic drugs may be ineffective in patients with [[hypokalemia]], and their toxic effects may be enhanced in patients with [[hyperkalemia]]. Therefore, potassium abnormalities should be corrected before starting Norpace or Norpace CR therapy.<ref name="dailymed.nlm.nih.gov">{{Cite web | last = | first = | title = NORPACE (DISOPYRAMIDE PHOSPHATE) CAPSULE, GELATIN COATED [G.D. SEARLE LLC DIVISION OF PFIZER INC] | url = http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=e2aa1642-d262-4520-bc6a-9fd3ad795677 | publisher = | date = | accessdate = 3 March 2014 }}</ref>
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| ==References==
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| {{Reflist}}
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| [[Category:Pyridines]]
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| [[Category:Sodium channel blockers]]
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| [[Category:Amides]]
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| [[Category:Cardiovascular Drugs]]
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| [[Category:Drugs]]
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