Verapamil

Indications

Verapamil Hydrochloride is used to treat high blood pressure, to prevent chest pain (angina), and to control certain fast heart rhythms, such as atrial fibrillation, atrial flutter and supraventricular tachycardia. It is sometimes also used to help prevent cluster headaches.

How It Works

Verapamil is a calcium channel blocker. It reduces the flow of calcium into the muscle cells of the heart and blood vessels. This relaxes and widens the arteries, lowers blood pressure, reduces the heart's workload and oxygen need, and slows the electrical signals through the heart so that a fast heartbeat becomes slower and steadier.

Dosage and Administration

Doses depend on the condition and the type of tablet. For high blood pressure or angina, adults often take 80 mg to 120 mg two or three times a day, or 120 mg to 240 mg once or twice daily as a slow-release tablet, as prescribed. Older people and those with liver problems may start lower. Swallow slow-release tablets whole with food. The injection is given by a doctor in hospital under heart monitoring.

Interactions

• Beta blockers (e.g. Atenolol, Metoprolol) can slow the heart too much; injected Verapamil must not be given close to an intravenous beta blocker.
• Verapamil raises levels of Digoxin, Simvastatin, Atorvastatin, Ciclosporin, Colchicine, Dabigatran and Carbamazepine.
• Clarithromycin, Erythromycin, Ketoconazole, Ritonavir and grapefruit juice raise Verapamil levels.
• Rifampicin and St John's Wort lower its effect.
• Other blood pressure medicines and alcohol add to its effect.

Contraindications

• Allergy to Verapamil.
• Very low blood pressure or cardiogenic shock.
• Second or third degree heart block, or sick sinus syndrome without a pacemaker.
• Uncontrolled heart failure.
• Atrial fibrillation or flutter with an accessory pathway, such as Wolff-Parkinson-White syndrome.
• Taking Ivabradine.

Side Effects

Constipation is the most common side effect. Others include headache, flushing, dizziness, tiredness, swollen ankles, nausea, slow heartbeat and gum overgrowth with long use.

Get urgent medical help if you faint, have a very slow or irregular heartbeat, severe breathlessness, chest pain, swelling of the face or throat, or yellowing of the skin or eyes.

Pregnancy and Lactation

Verapamil may be used in pregnancy only if your doctor decides the benefit outweighs the risk. It passes into breast milk in small amounts; ask your doctor before breastfeeding.

Precautions and Warnings

Tell your doctor if you have heart failure, a slow heart rate, liver or kidney disease, or a muscle disease such as myasthenia gravis. Do not stop suddenly, as angina may worsen. Get up slowly to avoid dizziness, and take care driving until you know how it affects you. Avoid grapefruit juice.

Overdose

Overdose can cause very low blood pressure, a dangerously slow heartbeat, heart block, high blood sugar and collapse. Seek emergency medical help at once; treatment is given in hospital.

Therapeutic Class

Calcium channel blocker (non-dihydropyridine), antihypertensive, antianginal and antiarrhythmic.

Storage

Store below 30°C in a dry place, away from light and out of the reach of children.