disopyramide

Contraindicated in:

Hypersensitivity;
Cardiogenic shock;
2nd- or 3rd-degree heart block;
Sick sinus syndrome (without a pacemaker);
Lactation: Lactation.

Use Cautiously in:

HF or left ventricular dysfunction (dose ↓ recommended);
Renal impairment (dose ↓ recommended if CCr ≤40 mL/min);
Hepatic impairment;
Prostatic enlargement;
Myasthenia gravis;
Glaucoma;
OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk;
Geri: May induce HF in older adults.

Adv. Reactions/Side Effects ⬆ ⬇

CV: HF, arrhythmias, dyspnea, edema, heart block, hypotension

EENT: dry eyes, blurred vision, dry throat

Endo: hypoglycemia

GI: constipation, dry mouth, abdominal pain, flatulence, nausea

GU: urinary hesitancy, urinary retention

Neuro: fatigue, dizziness, headache

Misc: impaired temperature regulation

Interactions ⬆ ⬇

Drug-drug:

May potentiate anticoagulant effect of warfarin.
Rifampin, phenobarbital, and phenytoin may ↓ levels and effectiveness.
Cimetidine orerythromycin may ↑ levels and risk of toxicity.
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 TCAs.
↑risk of arrhythmias with pimozide.

Drug-Natural Products:

↑anticholinergic effects with angel's trumpet, jimson weed, and scopolia.

Availability ⬆ ⬇

(Generic available)

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

Route/Dosage ⬆ ⬇

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

Renal Impairment

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

US Brand Names ⬆ ⬇

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.

Classifications ⬆ ⬇

Therapeutic Classification: antiarrhythmics (class I)

Pharmacokinetics ⬆ ⬇

Absorption: Well absorbed from the GI tract.

Distribution: Widely distributed to tissues

Metabolism/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).

Canadian Brand Names ⬆ ⬇

Time/Action Profile ⬆ ⬇

(antiarrhythmic effects)

ROUTE	ONSET	PEAK	DURATION
PO	0.5–3.5 hr	2.5 hr	1.5–8.5 hr
PO-CR	0.5–3.5 hr	4.9 hr	12 hr

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.
Rep: May cause fetal harm. Advise females of reproductive potential to notify health care professional promptly if pregnancy is planned or suspected and to avoid breastfeeding during therapy.

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Indications ⬇

Contraind./Precautions ⬆ ⬇