Tambocor XL is a brand name for the medication flecainide, which is classified as an antiarrhythmic drug. It is primarily used to prevent and treat a wide range of irregular heartbeats or arrhythmias. By blocking certain electrical signals in the heart that can cause an irregular heartbeat, Tambocor XL helps to maintain a normal heart rhythm and improve heart function. This extended-release formulation allows for more consistent levels of the medication in the bloodstream, potentially reducing the frequency of doses compared to immediate-release forms. It is important for patients to follow their healthcare provider's instructions closely when taking Tambocor XL, as it must be used with caution and under medical supervision due to the potential for serious side effects, especially in patients with certain pre-existing heart conditions.