Indications
Procainamide Hydrochloride is used to treat serious, life-threatening irregular heartbeats, mainly fast rhythms that start in the lower chambers of the heart (ventricular arrhythmias). It may also be used for some fast rhythms starting in the upper chambers, such as atrial fibrillation, under specialist care.
How It Works
Procainamide is a class IA antiarrhythmic. It slows the movement of sodium into heart muscle cells, which slows the electrical signals in the heart and makes the heart muscle less excitable. This helps restore and keep a normal, steady rhythm.
Dosage and Administration
The dose is set by a heart specialist according to the rhythm problem, body weight, kidney function and blood levels, so it is taken only as prescribed. Treatment is usually started in hospital with ECG monitoring; injections are given by a doctor or nurse. Tablets should be swallowed whole at evenly spaced times. Do not stop or change the dose on your own.
Interactions
- Other medicines that prolong the QT interval on the ECG (such as Amiodarone, Sotalol, Erythromycin, some antipsychotics and antidepressants) increase the risk of dangerous rhythms.
- Cimetidine, Trimethoprim and Amiodarone raise procainamide levels.
- It can strengthen muscle relaxants used in anaesthesia and weaken the effect of myasthenia gravis medicines such as Pyridostigmine.
- Blood pressure lowering medicines may cause excessive low blood pressure.
Contraindications
- Allergy to Procainamide or Procaine.
- Complete heart block or certain other conduction problems without a pacemaker.
- Long QT syndrome or torsades de pointes.
- Systemic lupus erythematosus.
- Myasthenia gravis.
Side Effects
Common effects include nausea, loss of appetite, diarrhoea, bitter taste, dizziness and low blood pressure. With long-term use, many people develop antibodies in the blood and some get a lupus-like illness with joint pain, fever, rash and chest pain. It can rarely cause a severe drop in white blood cells, which raises the risk of infection, and can itself trigger new dangerous heart rhythms.
Get urgent medical help if you have fainting, a racing or very irregular heartbeat, chest pain, fever, sore throat or mouth ulcers, unusual bruising or bleeding, joint pain with rash, or swelling of the face or difficulty breathing.
Pregnancy and Lactation
It should be used in pregnancy only when clearly needed under specialist care. It passes into breast milk, so breastfeeding is generally not recommended during treatment.
Precautions and Warnings
- Regular blood counts, ECGs and sometimes blood levels are needed, especially in the first 3 months.
- Use with care in kidney or liver disease, heart failure and older people; doses are adjusted.
- Keep potassium and magnesium levels normal.
- Tell all doctors and dentists that you take it.
Overdose
Overdose can cause very low blood pressure, slow or dangerous heart rhythms, confusion and fits. It is a medical emergency; get help immediately.
Therapeutic Class
Class IA antiarrhythmic.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children. Injections are stored as directed on the pack.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.