Drug Name

Calan (Verapamil)

Drug Uses

This drug is a calcium channel blocker. Calcium is involved in blood vessel contraction and in controlling the electrical impulses within the heart. By blocking calcium, calan relaxes and widens blood vessels and can normalize heartbeats. Calan is used to treat chest pain (angina), high blood pressure or irregular heartbeats. Ask your doctor or pharmacist about possible problems related to use of short-acting calcium channel blockers.

How Taken

This medication should be swallowed whole with a full glass of water unless your doctor directs you otherwise. This medication must be taken as directed to prevent chest pain. It is not effective if taken only when chest pain occurs. Do not stop taking this medication suddenly without your doctor's permission. Chest pain can occur if the medication is stopped too fast. Your dose may need to be gradually decreased.

Drug Class and Mechanism

Calan belongs to a class of medications, called calcium channel blockers. These medications block the movement of calcium into the muscle cells of the coronary arteries (the arteries supplying the heart) as well as the other arteries of the body. Since calcium is what triggers contraction of muscles, blocking entry of calcium relaxes the arterial muscles. This relaxation allows the arteries to become larger so that more blood can flow through them. Thus, calan is useful in treating and preventing chest pain (angina) resulting from spasm (contraction) of the coronary arteries that reduces the flow of blood to the heart. Relaxing the muscles lining the arteries in the rest of the body lowers blood pressure and thereby reduces the pressure against which the heart must pump blood. As a result, the heart works less and requires less oxygen-carrying blood. This allows the heart to work with the reduced flow of blood caused by coronary artery disease and prevents angina (which occurs whenever the flow of blood to the heart is inadequate). Calan also decreases the conduction of electrical impulses through the heart that control the coordination of contraction. As a result, the rate of contraction slows.

Missed Dose

If you miss a dose, take as soon as remembered; do not take if it is almost time for the next dose, instead, skip the missed dose and resume your usual dosing schedule. Do not "double-up" the dose to catch up.

Storage

Store at room temperature away from sunlight and moisture.

Warnings/Precautions

Before using this drug, tell your doctor your medical history, including: allergies (especially drug allergies), heart problems (e.g., heart rhythm disturbances, heart failure), liver or kidney disease, very low blood pressure, muscular dystrophy, brain tumors (cancer). Before heart surgery, tell your doctor you use this medicine. Calan prolongs and intensifies the effects of alcohol in your system. Avoid (or very carefully limit) alcoholic beverages while using this medication. Caution is advised when this drug is used in the elderly. This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor. This drug is excreted into breast milk and a decision should be made whether to stop the drug or avoid breast-feeding. Consult your doctor before breast-feeding.

Possible Side Effects

This drug may cause dizziness and lightheadedness especially during the first few days. Avoid activities requiring alertness. When you sit or lie down for a while, get up slowly to allow your body to adjust and minimize dizziness. You may also experience weakness, fatigue, nausea, muscle cramps, headache, flushing or constipation. These effects should disappear as your body adjusts to the medication. Inform your doctor if they become bothersome. Notify your doctor immediately if you develop: breathing difficulties, swelling of the hands or feet, irregular heartbeat, fever, stomach/abdominal pain, yellowing eyes and skin, dark urine. If you notice other effects not listed above, contact your doctor or pharmacist.

More Information

Laboratory tests (e.g., liver function tests) should be performed periodically to monitor for side effects. Do not share this medication with others.