COMPOSITION: Each capsule contains disopyramide phosphate equivalent to 100 mg disopyramide base or 150 mg disopyramide base.
PHARMACOLOGICAL CLASSIFICATION: A 6.2 Cardiac Depressants
PHARMACOLOGICAL ACTION: NORPACE is an antiarrhythmic agent, which shortens sinus node recovery time, lengthens the effective refractory period of the atrium and has minimal effect on the effective refractory period of the A-V node. The conduction times through the A-V node and the His-Purkinje system are relatively unaffected by NORPACE in the human. However, prolongation of A-V conduction time and conduction time in the His-Purkinje system has been observed in the dog. Also studies on the transmembrane potential of isolated dog Purkinje tissue have shown that there is a decrease in upstroke velocity and an increase in duration of the action potential, identifying NORPACE as a Type 1 antiarrhythmic agent.
INDICATIONS: NORPACE is indicated for the treatment of patients with various atrial and ventricular arrhythmias. It has been shown to be effective in the control of unifocal and multifocal premature ventricular contractions, premature atrial contractions and paroxysmal atrial tachycardia, when such arrhythmias appear either singly or in combination.
NORPACE has been shown to be equally effective in treatment of primary cardiac arrhythmias and those which occur in association with previous myocardial infarction. NORPACE may be used in patients receiving digitalis when adequate control of congestive heart failure has been achieved.
CONTRA-INDICATIONS: NORPACE is contra-indicated in the pre-existing A-V heart block, shock, glaucoma, urinary retention and hypersensitivity to the drug. NORPACE should not be administered to any patient with poorly compensated congestive heart failure.
WARNINGS: NORPACE should not be administered to patients with cardiomyopathy and associated congestive heart failure unless the patient is digitalized and adequately compensated. NORPACE should be used with caution in the presence of digitalis intoxication.
Development of acute urinary retention, for any reason, requires the discontinuation of NORPACE. Antiarrhythmic agents may be ineffective in patients with severe hypokalaemia. In such a patient, the potassium deficit should be corrected before instituting the NORPACE therapy.
DOSAGE AND DIRECTIONS FOR USE: The recommended initial adult oral dosage is 400 to 600 mg per day given as 100 mg or 150 mg capsules every 6 hours. Subsequent dosage adjustment up to 800 mg per day may be made, based on the therapeutic response.
SIDE-EFFECTS AND SPECIAL PRECAUTIONS: Anticholinergic effects may be experienced by some patients and will usually be manifested by dry mouth, constipation, blurring of vision, dizziness or difficulty in initiating a urinary stream. These effects are usually mild and transient in nature and may be eliminated by a reduction of dosage. Other reactions, which have been reported in association with the administration of NORPACE, include nausea, diarrhoea, abdominal pain or cramping, insomnia, syncope, tinnitus and maculopapular or erythematous cutaneous eruptions.
Animal teratology and reproduction studies with NORPACE have demonstrated no adverse effects. However, safe conditions for the use of NORPACE in pregnant women have not been established. The use of any drug in women of childbearing capability requires that the potential benefits of the drug be weighed against its possible hazards to the mother and foetus.
Clinical studies with NORPACE have not been carried out in children, nor have controlled studies been conducted in which NORPACE is used in combination with other antiarrhythmic agents.
NORPACE should be used with caution in patients with benign prostatic hypertrophy due to its anticholinergic action.
If first degree heart block develops in a patient receiving NORPACE, the dosage should be reduced. If the block persists despite the reduction of dosage, continuation of the drug must depend upon an assessment of risk versus benefit. The development of second or third degree heart block requires the discontinuation of NORPACE therapy, unless the heart is adequately controlled by a temporary or implanted ventricular pacemaker. In patients with impaired renal function, the therapeutic dose of NORPACE should be reduced and the electrocardiogram should be carefully monitored for lengthening of the P-R, QT and QRS intervals. NORPACE should be used with caution in the presence of digitalis intoxication.
KNOWN SYMPTOMS OF OVERDOSAGE AND PARTICULARS OF ITS TREATMENT: Overdosage may be manifested by anticholinergic effects, dry mouth, blurred vision, urinary hesitancy or retention and significant widening of the QRS complex. The physician should also be aware of the possibility of ventricular fibrillation or cardiac arrest occurring.
Treatment of overdosage is along conventional lines. Assisted respiration may be necessary, as may the use of a cardiac ventricular pacemaker.
It is advisable to administer intravenous infusions of sodium lactate (1,86% isotonic) 250 mL in 10 to 30 minutes repeated if needed. Ensure normal serum potassium.
IDENTIFICATION: NORPACE 100: Two-piece hard gelatine capsule with an opaque white body and an opaque caramel cap. “SEARLE 123”is printed in black on the body and the cap.
NORPACE 150: Two-piece hard gelatine capsule with an opaque caramel body and an opaque brown cap. “SEARLE 906”is printed in white on the body and the cap.
PRESENTATION: NORPACE 100 is supplied in bottles containing 100 capsules.
NORPACE 150 is supplied in bottles containing 100 capsules.
STORAGE INSTRUCTIONS: Store in a dry place below 30°C.
KEEP OUT OF REACH OF CHILDREN.
NORPACE 100/150 Capsules