Verapamil

Verapamil, sold under various trade names, is a medication used for the treatment of high blood pressure, angina (chest pain from not enough blood flow to the heart), and supraventricular tachycardia. It may also be used for the prevention of migraines and cluster headaches. It is given by mouth or by injection into a vein. Verapamil, sold under various trade names, is a medication used for the treatment of high blood pressure, angina (chest pain from not enough blood flow to the heart), and supraventricular tachycardia. It may also be used for the prevention of migraines and cluster headaches. It is given by mouth or by injection into a vein. Common side effects include headache, low blood pressure, nausea, and constipation. Other side effects include allergic reactions and muscle pains. It is not recommended in people with a slow heart rate or heart failure. It is believed to cause problems for the baby if used during pregnancy. It is in the non–dihydropyridine calcium channel blocker family of medications. Verapamil was approved for medical use in the United States in 1981. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Verapamil is available as a generic medication. The wholesale cost in the developing world is about US$1.71–2.70 per month. In the United States a month of treatment costs $25–50. Long acting formulations exist. In 2016 it was the 130th most prescribed medication in the United States with more than 5 million prescriptions. Verapamil is used for controlling ventricular rate in supraventricular tachycardia and migraine headache prevention. It is a class-IV antiarrhythmic and more effective than digoxin in controlling ventricular rate. Verapamil is not listed as a first line agent by the guidelines provided by JAMA in JNC-8. However, it may be used to treat hypertension if patient has co-morbid atrial fibrillation or other types of arrhythmia. Verapamil is also used intra-arterially to treat cerebral vasospasm. Verapamil is used to treat the condition cluster headache. Use of verapamil is generally avoided in people with severe left ventricular dysfunction, hypotension (systolic blood pressure less than 90 mm Hg), cardiogenic shock, and hypersensitivity to verapamil. It is also contraindicated in people with atrial flutter or fibrillation. The most common side effect of Verapamil is constipation (7.3%). Other side effects include: dizziness (3.3%), nausea (2.7%), low blood pressure (2.5%), and headache 2.2%. Other side effects seen in less than 2% of the population include: edema, congestive heart failure, pulmonary edema, fatigue, elevated liver enzymes, shortness of breath, low heart rate, atrioventricular block, rash and flushing. Along with other calcium channel blockers, verapamil is known to induce gingival enlargement. Acute overdose is often manifested by nausea, weakness, slow heart rate, dizziness, low blood pressure, and abnormal heart rhythms. Plasma, serum, or blood concentrations of verapamil and norverapamil, its major active metabolite, may be measured to confirm a diagnosis of poisoning in hospitalized patients or to aid in the medicolegal investigation of fatalities. Blood or plasma verapamil concentrations are usually in a range of 50–500 μg/l in persons on therapy with the drug, but may rise to 1–4 mg/l in acute overdose patients and are often at levels of 5–10 mg/l in fatal poisonings.