Ranexa for Treating Angina

Ranexa (ranolazine) is a relatively new drug with a unique mechanism of action that's used mainly for the treatment of chronic stable angina. It is sometimes used for other cardiovascular conditions that produce chest pain as well. 

What Is Angina?

Angina is pain or discomfort in the chest that results from the heart muscle being deprived of oxygen-rich blood. Some describe the feeling as pressure or squeezing, and the discomfort can be felt in the shoulders, arms, neck, jaw, or back, in addition to the chest. Angina pain may even feel like indigestion.

Angina is a symptom rather than a disease in and of itself. Usually, it signals that a person has atherosclerotic coronary artery disease (CAD), resulting in a narrowing of one or more of the coronary arteries. When people with CAD stress their hearts (for instance, when they exert themselves), the region of the heart muscle that is supplied by the narrowed artery can become ischemic, which means it is deprived of oxygen. When the heart muscle becomes ischemic, angina often occurs.

How Does Ranexa Benefit Angina?

Ranexa has a unique mechanism of action, and as a result it can be added to other medications to treat angina (such as beta-blockers and nitrates) to improve the control of this symptom.

Originally it was believed that Ranexa caused the heart muscle to switch from using fatty acids to glucose for energy production. This process would reduce the amount of oxygen the heart muscle needed to function—and, thus, would diminish ischemia.

More recently, however, researchers learned that the principal effect of Ranexa is actually to block what is called the "late inward sodium channel" in heart cells. This sodium channel increases the calcium concentration inside cardiac cells and increases the muscle contraction and energy usage of the heart muscle.

By blocking this sodium channel (which it does only in ischemic cells, not healthy heart cells), Ranexa improves the metabolism in ischemic heart cells, reducing damage to the heart muscle and also reducing angina symptoms.

When Is Ranexa Useful?

The chief use of Ranexa is to treat people with chronic stable angina. Ranexa can significantly reduce the frequency of angina episodes and increase the amount of exercise that can be performed without experiencing angina. It is usually combined with standard drug therapy for angina.

In addition to standard therapy, a few studies have suggested that Ranexa may also be useful in managing unstable angina, when the heart doesn't get enough blood flow or oxygen.

Ranexa also has shown promise in the treatment of microvascular angina, chest pain that's due to abnormalities in the tiny arteries of the heart.

How Is Ranexa Taken?

Ranexa comes as 500 milligram and 1,000 milligram extended-release tablets, and generic forms of ranolazine are also available. The usual dose is 500 milligrams twice per day, but it may be increased to 1,000 milligrams twice per day.

Ranexa is one of the drugs that should not be taken along with grapefruit or grapefruit juice, which can increase the blood levels of Ranexa and make side effects more likely.

Side Effects with Ranexa

The most common reported side effects of Ranexa are headache, constipation, and nausea. Other less serious side effects may include:

• Dizziness or a spinning sensation
• Headache
• Dry mouth
• Weakness
• Ringing in the ears

In addition, while taking Ranexa, it is important to pay attention to any of the following serious side effects and immediately call your physician if they occur:

• Feeling as though you might pass out
• Swelling in the hands, ankles, or feet
• Slow, fast, or pounding heartbeats
• Tremors
• Blood in the urine
• Urinating less frequently or not at all
• Shortness of breath
• Rashes, bruising, tingling, numbness, pain, or muscle weakness

Initially, a chief concern about Ranexa was that it can prolong the QT interval (a measurement of electrical activity within the heart) on an ECG (electrocardiogram). Some drugs with this effect can increase the risk of developing dangerous heart arrhythmias.

However, careful studies have shown this risk to be minimal or nonexistent with Ranexa. In fact, Ranexa now has been shown to actually reduce the risk of developing ventricular arrhythmias and atrial fibrillation (conditions that cause abnormal heart rhythms) and is sometimes used off-label as an antiarrhythmic drug.

In addition, people with cirrhosis (scarring) of the liver should not take Ranexa, and neither should people taking Saint-John’s wort and certain other medications for: 

• Fungus infection
• Depression
• HIV
• Tuberculosis (TB)
• Seizures

Studies suggest that side effects are more common in people over 75 years of age, so this drug should be used with caution in older individuals. Pregnant women are advised not to take Ranexa.

A Word From Verywell

Ranexa is a unique drug that has proven to be useful in the treatment of chronic stable angina. It can be useful to patients with other chest pain syndromes as well.