disopyramide phosphate at a glance
Medicine class
Class Ia antiarrhythmic
Main role
Prevention or control of selected atrial and ventricular arrhythmias
Formulation
Prolonged-release tablet that must not be crushed or chewed
Key monitoring
ECG, potassium and blood glucose monitoring may be required
What is disopyramide phosphate used for?
The selected prolonged-release product is licensed to prevent or control several cardiac arrhythmias.
Maintaining normal rhythm after electrical or medicine-assisted conversion
Preventing arrhythmias after myocardial infarction
Treating persistent atrial or ventricular extrasystoles, paroxysmal supraventricular tachycardia and Wolff–Parkinson–White syndrome
Suppressing arrhythmias during surgery
Controlling arrhythmias associated with digitalis or similar cardiac glycosides
How does disopyramide phosphate work?
It blocks fast sodium channels, slowing electrical conduction and increasing the time before heart cells can be activated again. It also has negative inotropic and anticholinergic effects.
disopyramide phosphate preparations and strengths
Modified-release tablet
Route: Oral
Strengths: 250 mg
How to take disopyramide phosphate
Take it exactly as prescribed. The selected product is taken by mouth.
Swallow the prolonged-release tablet with water.
Do not crush or chew it because this may disrupt prolonged release.
Do not change or stop treatment without advice from the prescribing team.
Ask a pharmacist before using non-prescription or herbal products.
disopyramide phosphate side effects
Common or expected effects
- Frequency not known: dry mouth, nausea, vomiting, abdominal pain, reduced appetite, constipation or diarrhoea
- Frequency not known: blurred or double vision, difficulty focusing, dizziness or cognitive problems
- Frequency not known: difficulty passing urine or sexual dysfunction
Get urgent medical advice
- New or worsening abnormal heartbeat, fainting, severe dizziness or low blood pressure
- Breathlessness or swelling that may indicate worsening heart failure
- Severe hypoglycaemia, including confusion, seizure or unconsciousness
- Inability to pass urine, severe constipation or symptoms of bowel obstruction
- Fever, severe sore throat or mouth ulcers
- Yellow skin or eyes
- Swelling of the face, lips, tongue or throat, or difficulty breathing
disopyramide phosphate in pregnancy
Safety in human pregnancy has not been established, and disopyramide may stimulate uterine contractions. It should be considered only when the expected benefit outweighs possible maternal and fetal risks. Obtain specialist advice and do not stop cardiac treatment without speaking to the prescribing team.
disopyramide phosphate while breastfeeding
Disopyramide and its active metabolite can enter breast milk, but evidence is limited. Use is recommended only when considered essential, with specialist assessment, close observation of the infant and consideration of alternative feeding.
disopyramide phosphate interactions
Disopyramide has important cardiac, metabolic and anticholinergic interactions. A prescriber or pharmacist should review all prescribed, non-prescription and herbal products.
Other antiarrhythmics and medicines that prolong QT
Combined effects can provoke serious ventricular arrhythmias; many combinations are contraindicated or should be avoided.
Macrolide antibiotics and azole antifungals
They may increase disopyramide concentrations; macrolides can also increase QT-related risk.
Sildenafil, tadalafil and other PDE5 inhibitors
Additive QT prolongation is possible, so concomitant use is not recommended.
Common questions about disopyramide phosphate
Answers are fully visible for fast scanning and source review.
Why does disopyramide phosphate require ECG monitoring?
It can prolong QT, widen QRS complexes, impair conduction or provoke a new arrhythmia.
Can disopyramide phosphate make an arrhythmia worse?
Yes. It can worsen an existing rhythm problem or cause a new one, particularly with low potassium, structural heart disease or interacting medicines.
Can disopyramide phosphate cause low blood sugar?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.