Flecainide acetate, often known by the trade name Tambocor, is a prescription medication used to manage heart rhythm disorders. Classified as a Class IC antiarrhythmic, the drug slows electrical signals in the heart to maintain a normal, steady rhythm. It primarily treats paroxysmal atrial fibrillation (PAF) and paroxysmal supraventricular tachycardia (PSVT), which are types of abnormally rapid heart rates. Like all medications, flecainide carries a risk of side effects.
Flecainide and Gastrointestinal Side Effects
Constipation is a side effect of flecainide, reported in approximately 4.4% of patients. This gastrointestinal (GI) symptom is typically mild or moderate. Flecainide blocks sodium channels to slow electrical conduction, and this mechanism may have secondary effects on the smooth muscle lining the digestive tract. This interference can slow the movement of the intestines, leading to delayed transit time and constipation.
Other common GI reactions include nausea, observed at a rate of almost 9%. Abdominal pain, stomach discomfort, and, less frequently, diarrhea have also been reported. While flecainide often has fewer GI side effects compared to some other antiarrhythmic drugs, these symptoms can significantly impact a patient’s quality of life. Patients experiencing persistent GI symptoms should discuss them with their healthcare provider, who can assess if the symptoms are drug-related or due to other causes.
Other Common Adverse Reactions
Side effects affecting the nervous system are common. Dizziness is highly reported, sometimes affecting up to 30% of patients, and can be accompanied by visual disturbances. These visual changes may include blurred vision, difficulty focusing, or seeing spots, observed in up to 28% of individuals. Other neurological symptoms include headaches, fatigue, and a fine tremor.
Cardiovascular side effects include the potential for proarrhythmia, meaning the drug can cause new or worsen existing heart rhythm problems. As a sodium channel blocker, flecainide causes subtle changes in the heart’s electrical activity, such as prolonging the PR and QRS intervals seen on an electrocardiogram. These changes reflect slower electrical conduction, which is the drug’s therapeutic effect but also the source of its risk. In rare cases, this potential can lead to dangerous ventricular arrhythmias or a worsening of heart failure symptoms, requiring immediate medical evaluation.
Managing Drug-Related Constipation
Management of constipation linked to flecainide begins with lifestyle adjustments. Patients should increase their daily intake of dietary fiber through fruits, vegetables, and whole grains to add bulk to stool. Adequate fluid intake is important, as hydration softens stool and facilitates easier passage. Regular physical activity helps stimulate the muscles of the intestines and encourages normal bowel function.
If these adjustments do not provide sufficient relief, over-the-counter remedies can be considered, but only after consultation with a prescribing physician. Bulk-forming laxatives, like psyllium, and osmotic laxatives, such as polyethylene glycol, are generally considered first-line options because they work gently to increase water content in the stool. Stimulant laxatives may be used for short periods but are reserved for when other treatments have not been successful. Patients must contact their healthcare provider immediately if they experience severe abdominal pain, persistent constipation that does not respond to basic remedies, or notice blood in their stool.