Rythmodan

disopyramide

(dye-soe-peer-a-mide) ,

Norpace

(trade name),

Norpace CR

(trade name),

Rythmodan

(trade name)

Classification

Therapeutic: antiarrhythmics
Pregnancy Category: C

Indications

Treatment of ventricular tachycardia.Treatment/prevention of supraventricular tachyarrhythmias.

Action

Decreases myocardial excitability and conduction velocity.
Has anticholinergic properties.
Little effect on heart rate but has a direct negative inotropic effect.

Therapeutic effects

Suppression of ventricular arrhythmias.

Pharmacokinetics

Absorption: Well absorbed from the GI tract.
Distribution: Widely distributed; enters breast milk.
Metabolism and Excretion: Metabolized by the liver; 10% excreted unchanged in the feces, 50% excreted unchanged by the kidneys.
Half-life: 8–18 hr (↑ in hepatic or renal impairment).

Time/action profile (antiarrhythmic effects)

ROUTEONSETPEAKDURATION
PO0.5–3.5 hr2.5 hr1.5–8.5 hr
PO-CR0.5–3.5 hr4.9 hr12 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Cardiogenic shock; 2nd-or 3rd-degree heart block; Sick sinus syndrome (without a pacemaker).
Use Cautiously in: HF or left ventricular dysfunction (dose ↓ recommended); Hepatic or renal insufficiency (dose ↓ recommended if CCr ≤40 mL/min); Prostatic enlargement; Myasthenia gravis; Glaucoma; Geriatric: Appears on Beers list. May induce heart failure in elderly patients; Obstetric / Lactation / Pediatric: Safety not established.

Adverse Reactions/Side Effects

Central nervous system

  • dizziness
  • fatigue
  • headache

Ear, Eye, Nose, Throat

  • blurred vision
  • dry eyes
  • dry throat

Cardiovascular

  • HF (life-threatening)
  • arrhythmias
  • AV block
  • dyspnea
  • edema
  • hypotension

Gastrointestinal

  • constipation (most frequent)
  • dry mouth (most frequent)
  • abdominal pain
  • flatulence
  • nausea

Genitourinary

  • urinary hesitancy (most frequent)
  • urinary retention (most frequent)

Endocrinologic

  • hypoglycemia

Miscellaneous

  • impaired temperature regulation

Interactions

Drug-Drug interaction

May potentiate anticoagulant effect of warfarin.Rifampin, phenobarbital, and phenytoin may ↓ blood levels and effectiveness.Cimetidine orerythromycin may ↓ metabolism and ↑ blood levels.May have additive toxic cardiac effects when used with other antiarrhythmics (prolonged conduction and ↓ cardiac output), especially verapamil —avoid using disopyramide for 48 hr before or 24 hr after.Anticholinergic side effects may be additive with other drugs having anticholinergic properties, including antihistamines and tricyclic antidepressants.↑ risk of arrhythmias with pimozide.↑ anticholinergic effects with angel's trumpet, jimson weed, and scopolia.

Route/Dosage

Oral (Adults >50 kg) 150 mg q 6 hr (as immediate-release capsules) or 300 mg q 12 hr (as CR dosage form; not to exceed 800 mg/day).
Oral (Adults <50 kg or Patients with Poor Left Ventricular Function) 100 mg q 6–8 hr (as immediate-release capsules) or 200 mg q 12 hr (as CR dosage form).
Oral (Children 12–18 yr) 6–15 mg/kg daily, in divided doses q 6 hr.
Oral (Children 4–12 yr) 10–15 mg/kg daily in divided doses q 6 hr.
Oral (Children 1–4 yr) 10–20 mg/kg daily in divided doses q 6 hr.
Oral (Children <1 yr) 10–30 mg/kg daily in divided doses q 6 hr.

Renal Impairment

Oral (Adults) CCr >40 mL/min or patients with hepatic impairment—100 mg q 6 hr; CCr 30–40 mL/min—100 mg q 8 hr; CCr 15–30 mL/min—100 mg q 12 hr; CCr <15 mL/min—100 mg q 24 hr as immediate-release dosage form.

Availability (generic available)

Capsules: 100 mg, 150 mg
Extended-release capsules: 100 mg, 150 mg

Nursing implications

Nursing assessment

  • Monitor BP, pulse, and ECG before and routinely throughout therapy. Check pulse before administering medication; withhold and notify health care professional if <60 or >120 bpm or if changes in rhythm.
  • Monitor intake and output ratios and daily weight; assess for edema and urinary retention daily.
  • Assess patient for signs of heart failure (peripheral edema, rales/crackles, dyspnea, weight gain, jugular venous distention). Notify health care professional if these occur.
  • Lab Test Considerations: Renal and hepatic functions and serum potassium levels should be evaluated periodically throughout therapy.
    • May cause elevated serum BUN, cholesterol, and triglyceride levels.
    • May cause decreased blood glucose concentrations.

Potential Nursing Diagnoses

Decreased cardiac output (Indications)
Impairedoral mucous membrane (Side Effects)

Implementation

  • Do not confuse disopyramide with desipramine.
  • When changing from quinidine sulfate to disopyramide, regular maintenance dose of disopyramide may be given 6–12 hr after last dose of quinidine sulfate.
    • Extended-release form (CR formulations) is indicated for maintenance therapy only. When changing from regular form to extended-release forms, give the first dose of extended-release form 6 hr after the last regular dose.
  • Oral: Administer medication on an empty stomach, 1 hr before or 2 hr after meals. CR form must be swallowed whole; do not break open, crush, or chew.
    • Pharmacist may prepare a suspension with 100-mg capsules and cherry syrup.

Patient/Family Teaching

  • Advise patient to take medication around the clock, as directed. Do not discontinue medication without consulting health care professional. If a dose is missed, take as soon as remembered unless within 4 hr of next dose. Do not double doses.
  • Medication may cause dizziness. Caution patients to avoid driving or other activities requiring alertness until response to medication is known.
  • Instruct patient to change positions slowly to minimize orthostatic hypotension.
  • Advise patient that frequent mouth rinses, good oral hygiene, and sugarless gum or candy may help relieve dry mouth.
  • Caution patient to avoid extremes of temperature, because this medication may cause impairment of body temperature regulation. Patient should use sunscreen and protective clothing to prevent photosensitivity reactions.
  • Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care professional before taking other Rx, OTC, herbal products, or alcohol.
  • If constipation becomes a problem, advise patient that increasing bulk and fluids in the diet and exercising may minimize constipation.
  • Instruct patient to notify health care professional if dry mouth, difficult urination, constipation, or blurred vision persists.

Evaluation/Desired Outcomes

  • Suppression of PVCs and ventricular tachycardia.
  • Prevention of further arrhythmias.

Rythmodan

A brand name for DISOPYRAMIDE.
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