Disopyramide Phosphate

Contraindications

• Preexisting 2nd or 3rd degree AV block (if an artificial pacemaker has not been inserted).b

• Cardiogenic shock.b

• Known hypersensitivity to disopyramide.b

Warnings/Precautions

Warnings

In CAST study, excessive rate of mortality and nonfatal cardiac arrest reported in patients with asymptomatic, non-life-threatening ventricular arrhythmias and recent MI (>6 days but <2 years previously) who were receiving encainide or flecainide compared with placebo.a

Because of disopyramide’s arrhythmogenic potential and the lack of evidence for improved survival for class I antiarrhythmic agents,112 116 117 118 use disopyramide only for life-threatening arrhythmias.112 Use in less severe arrhythmias currently is not recommended, and treatment of asymptomatic VPCs should be avoided.112

Initiate therapy only in a hospital setting.112

May cause or worsen CHF or produce severe hypotension.a Hypotension occurs more commonly in patients with primary cardiomyopathy or inadequately compensated CHF.a

Do not use in patients with uncompensated or marginally compensated CHF or hypotension unless the CHF or hypotension is secondary to cardiac arrhythmia.a In patients with a history of heart failure, cardiac function must be carefully maintained, including optimal digitalization.a

If hypotension occurs or CHF worsens, discontinue disopyramide and, if necessary, resume therapy at a lower dosage only after establishing adequate cardiac compensation.a

Increased risk of severe hypotension in patients with myocarditis or other cardiomyopathy.b Do not administer a loading dose to such patients; select initial dosage and make subsequent dosage adjustments under close supervision.b (See Patients with Cardiomyopathy or Possible Cardiac Decompensation under Dosage and Administration.)

Possible worsening of existing arrhythmias or occurrence of new arrhythmias, including VT and VF associated with prolonged QT interval.a b Increased risk of such effects if used concomitantly with other drugs (i.e., quinidine) that prolong the QT interval.a b

a b

If a QT prolongation >25% occurs and if ectopy continues, monitor patient closely.a Consider discontinuance of disopyramide.a

Hypoglycemia reported rarely.a b

Monitor blood glucose concentrations closely in patients with compromised glucoregulatory mechanisms in the absence of food (e.g., patients with CHF, chronic malnutrition, hepatic or renal disease, those using alcohol or receiving certain drugs [e.g., β-adrenergic blockers]).b

Reserve combined use for serious arrhythmias unresponsive to monotherapy; monitor closely.a

Reduce dosage if first-degree AV heart block occurs.b If the block persists, weigh the benefit of therapy against the potential risk of higher degrees of AV block.b

If second- or third-degree AV block or unifascicular, bifascicular, or trifascicular block occurs, discontinue disopyramide therapy, unless the ventricular rate is adequately controlled by an artificial pacemaker.b

Possible anticholinergic effects; do not use in patients with glaucoma, myasthenia gravis, or urinary retention without instituting adequate overriding measures (e.g., pilocarpine ophthalmic drops for glaucoma, catheter drainage or operative relief for urinary retention).a

Possible increased risk of urinary retention in males with benign prostatic hypertrophy.a

Measure intraocular pressure before initiating therapy in patients with a family history of glaucoma.a

May precipitate myasthenic crisis; use with caution in patients with myasthenia gravis.a

Use with caution in geriatric patients. (See Geriatric Use under Cautions.)a

General Precautions

Possible enhanced AV conduction; patients with atrial flutter or fibrillation should be digitalized prior to administration.b

Use with caution in patients with sick sinus syndrome (including bradycardia-tachycardia syndrome), Wolff-Parkinson-White syndrome, or bundle-branch block, since effects of the drug in these conditions are unpredictable.b

Correct abnormalities in serum potassium concentration before initiating therapy.a

May be ineffective in patients with hypokalemia and toxic effects may be enhanced in patients with hyperkalemia.a

Specific Populations

Category C.a

Distributed into milk.112 Discontinue nursing or the drug.112

Safety and efficacy not established.a However, disopyramide has been used in children.a b (See Pediatric Patients under Dosage and Administration.)

Insufficient experience in patients ≥65 years of age to determine whether geriatric patients respond differently than younger adults.a

Select dosage with caution because of age-related decreases in hepatic, renal, and/or cardiac function and potential for concomitant disease and drug therapy.a (See Geriatric Patients under Dosage and Administration.)

Substantially eliminated by kidneys; assess renal function periodically and adjust dosage accordingly.a (See Renal Impairment under Dosage and Administration.)

Possible anticholinergic effects; not generally recommended for use in patients with glaucoma, urinary retention, or benign prostatic hypertrophy unless adequate overriding measures are taken.a (See Anticholinergic Effects under Warnings.)

Increased plasma half-life; dosage adjustment recommended.a (See Hepatic Impairment under Dosage and Administration.)

Patients with cardiac dysfunction are more likely to have comorbid hepatic impairment.a

Carefully monitor ECG for prolongation of PR interval, evidence of QRS widening, or other signs of toxicity.a

Increased plasma half-life; dosage adjustments necessary based on degree of renal impairment.a (See Renal Impairment under Dosage and Administration.)

Carefully monitor ECG for prolongation of PR interval, evidence of QRS widening, or other signs of toxicity.a

Not recommended for use in patients with severe renal insufficiency (Clcr ≤40 mL/min).a

Common Adverse Effects

Anticholinergic effects (e.g., dry mouth, urinary hesitancy, constipation, blurred vision, dry nose/eyes/throat), urinary frequency/urgency, urinary retention, nausea, pain/bloating/gas, dizziness, general fatigue/muscle weakness, headache, malaise, aches/pains.a b

Consult your pharmacist.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

Notes

Missed Dose

Consult your pharmacist.

Storage

Consult your pharmacist.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

Information last revised July 2016. Copyright(c) 2016 First Databank, Inc.