Disopyramide Phosphate

Generic Name

Disopyramide Phosphate

Other Names

• Norpace
• Rythmodan

Drug Class

• Antiarrhythmic

Chemical Formula

C21H29N3O4 · H3PO4

Molecular Weight

437.45 g/mol

Mechanism of Action

• Blocks sodium channels in cardiac cells, leading to decreased excitability and conduction velocity

Indications

• Treatment of ventricular arrhythmias

Common Dosage Forms

• Capsule

Typical Dosage

• 100 mg to 400 mg every 6 to 8 hours

Pediatric Dosage

• Not established

Geriatric Dosage

• Reduce dose due to age-related decrease in renal function

Side Effects

• Anticholinergic effects (dry mouth, constipation)
• Arrhythmias
• Heart failure exacerbation
• Dizziness
• Blurred vision

Contraindications

• Hypersensitivity to disopyramide
• Heart block
• Severe heart failure

Pregnancy Category

• C - Risk cannot be ruled out

Lactation Safety

• Not recommended during breastfeeding due to limited data

Drug Interactions

• Quinidine
• Amiodarone
• Beta-blockers

Overdose Symptoms

• Severe arrhythmias
• Hypotension
• Convulsions

Antidote for Overdose

• Supportive care and symptomatic treatment

Storage Conditions

• Store at room temperature away from moisture and heat

Pharmacokinetics

• Absorption: Well absorbed orally
• Distribution: Highly protein-bound
• Metabolism: Hepatic
• Excretion: Renal

Precautions

• Regular monitoring of ECG and blood levels
• Avoid abrupt withdrawal

Warnings

• May cause QT prolongation
• Risk of proarrhythmia

Others

• Dose adjustment may be needed in patients with renal impairment