Verapamil ER treats high blood pressure or controls angina. The list of conditions treated is short partly due to the fact that this drug is an extended release formula. In tablets that don’t have a slow release, verapamil may have additional approved applications. For example, it might address certain types of arrythmias like supraventricular tachycardia, and atrial fibrillation or flutter. Some controversial applications of extended or non-extended release types of this medication have also been suggested; examples of off-label uses include treating migraines and cluster headaches, and the manic phases of bipolar disorder.
The group of medicines to which verapamil ER belongs is called the calcium channel blockers (CCBs). These medications reduce the amount of calcium that flows into heart cells. The action of CCBs provides greater and more efficient contractility of the heart and dilates or opens blood vessels to lessen resistance.
As a blood pressure medication, verapamil ER is useful due to the way it influences heart and blood vessel function. It can also reduce episodes of angina, but it is not fast acting like nitroglycerin. Patients may still need to keep nitroglycerin or another medication on hand for breakthrough angina pain.
Some pharmaceutical companies occasionally combine verapamil with other CCBs. This may increase its effectiveness in lowering blood pressure. These combination drugs are not advisable for everyone and may increase patients' risk of developing hypotension.
Each calcium channel blocker works differently, and many of them are used to treat certain arrhythmias. Verapamil ER isn’t always a first choice, but non-extended release tablets containing the drug could be used in this way. Often, arrhythmia control may require a more frequent application of medicine than ER formulas provide.
CCBs don’t treat all arrythmias. Heart rhythm dysfunctions like atrioventricular block or sick sinus syndrome can contraindicate the use of verapamil ER. Also, it’s important to note that all CCBs occasionally induce irregular heart rhythms and must be used carefully.
At present, the wisdom of using verapamil ER for conditions like cluster headaches or bipolar disorder has not been proven. Other calcium channel blockers have shown some limited effectiveness in treating these conditions. Unfortunately, all of them increase the risk of very dangerous side effects, including potentially life-threatening arrhythmias. It’s not clear that CCBs are ever a good choice for treatment of these conditions, unless no other options have worked effectively. More study is needed to determine if these off-label treatments justify their risks.