Norpace

Uses

Norpace is used for the ventricular arrhythmias, especially after myocardial infarction, supraventricular arrhythmias.

Norpace is also used to associated treatment for these conditions: Arrhythmia of ventricular origin

How Norpace works

Norpace is a Type 1A antiarrhythmic drug (ie, similar to procainamide and quinidine). It inhibits the fast sodium channels. In animal studies Norpace decreases the rate of diastolic depolarization (phase 4) in cells with augmented automaticity, decreases the upstroke velocity (phase 0) and increases the action potential duration of normal cardiac cells, decreases the disparity in refractoriness between infarcted and adjacent normally perfused myocardium, and has no effect on alpha- or beta-adrenergic receptors.

Dosage

Norpace dosage

The recommended dose of Norpace is 400 mg /day in 4 divided doses (100 mg capsule 6 hourly).

Patients with renal insufficiency should take 100 mg capsule according to the schedule given below:

Creatinine clearance (ml/min) >15: Approximate dosing q 8 hrq 12 hrq 24 hr

Patients in whom rapid control of ventricular arrhythmia is essential, an initial loading dose of 300 mg Norpace is recommended, followed by the appropriate maintenance dosage.

Side Effects

Usually Norpace is well tolerated but occasionally in some cases dry mouth/ nose/ eye, nausea, vomiting, diarrhea, bloating, blurred vision, urinary problems, headache, skin rash, dizziness, nervousness & impotence (1-3%) may occur.

Toxicity

LD₅₀=580 mg/kg in rats

Precaution

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.

Food Interaction

• Avoid alcohol.
• Take with or without food. The absorption is unaffected by food.

[Moderate] MONITOR: Grapefruit juice may increase the plasma concentrations of orally administered drugs that are substrates of the CYP450 3A4 isoenzyme.

The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit.

Because grapefruit juice inhibits primarily intestinal rather than hepatic CYP450 3A4, the magnitude of interaction is greatest for those drugs that undergo significant presystemic metabolism by CYP450 3A4 (i.e., drugs with low oral bioavailability).

In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands.

Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition.

Pharmacokinetic interactions involving grapefruit juice are also subject to a high degree of interpatient variability, thus the extent to which a given patient may be affected is difficult to predict.

MANAGEMENT: Patients who regularly consume grapefruit or grapefruit juice should be monitored for adverse effects and altered plasma concentrations of drugs that undergo significant presystemic metabolism by CYP450 3A4.

Grapefruit and grapefruit juice should be avoided if an interaction is suspected.

Orange juice is not expected to interact with these drugs.

Norpace Alcohol interaction

[Minor] Ethanol significantly increases the renal elimination of disopyramide, apparently by inducing diuresis (inhibition of antidiuretic hormone).

Limited data show that ethanol does not, however, significantly affect the elimination half-life or total plasma clearance of disopyramide. No special precautions appear to be necessary.

Norpace Drug Interaction

Major: metoprolol, metoprololModerate: diphenhydramine, diphenhydramineUnknown: aspirin, aspirin, rosuvastatin, rosuvastatin, duloxetine, duloxetine, apixaban, apixaban, acetaminophen, acetaminophen, clopidogrel, clopidogrel, ascorbic acid, ascorbic acid, cholecalciferol, cholecalciferol

Norpace Disease Interaction

Major: cardiovascular dysfunction, proarrhythmic effects, anticholinergic activity, sinus-AV node dysfunctionModerate: electrolyte imbalance, hepatic dysfunction, hypoglycemia, renal dysfunction

Elimination Route

Nearly complete

Half Life

6.7 hours (range 4-10 hours)

Elimination Route

In healthy men, about 50% of a given dose of disopyramide is excreted in the urine as the unchanged drug, about 20% as the mono-N-dealkylated metabolite and 10% as the other metabolites.

Pregnancy & Breastfeeding use

Pregnancy: There are no adequate and well-controlled studies in pregnant women. Norpace should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Lactation: Because of the potential for serious adverse reactions in nursing infants from Norpace, a decision should be made whether to discontinue nursing or to discontinue the drug , taking into account the importance of the drug to the mother

Contraindication

Norpace is contraindicated in the pre-existing A-V heart block, shock, glaucoma, urinary retention and known hypersensitivity to the drug.

Acute Overdose

Deliberate or accidental over dosage of oral Norpace may be followed by apnea, loss of consciousness & loss of spontaneous respiration. In such a case immediate hospitalization and all life saving measures should be taken.

Innovators Monograph

You find simplified version here Norpace