Ranexa for Treating Angina

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

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 heart muscle becomes ischemic, angina often occurs.

Ranexa has a unique mechanism of angina, and as a result it can be added to other anti-anginal medications (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, which 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 of 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, so it does not affect “normal” heart cells), Ranexa improves the metabolism in ischemic heart cells, reducing damage to the heart muscle, and also reducing angina symptoms.

The chief utility of Ranexa is in the treatment of a person with chronic, stable angina. Ranexa can significantly reduce the frequency of angina episodes and increases the amount of exercise that can be performed without experiencing angina. It is usually combined with more standard anti-anginal drug therapy.

A few studies have suggested that Ranexa may also be useful (in addition to standard therapy) in the management of unstable angina.

Ranexa has also been used by some experts to treat chest pain that has not responded to standard therapy in people with hypertrophic cardiomyopathy.

In addition, Ranexa has shown promise in the treatment of microvascular angina.

Ranexa comes as 500 mg and 1000 mg extended-release tablets, and generic forms of ranolazine are also available. The usual dose is 500 mg twice per day, but may be increased to 1000 mg twice per day.

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

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 seek immediate guidance from 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" on the ECG (a measurement of electrical activity within the heart). 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, 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 St. 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, and this drug should be used with caution in older individuals. Pregnant women are advised not to take Ranexa.

Ranexa is a unique anti-anginal drug that has proven to be useful in the treatment of chronic stable angina, and that can be used in other chest pain syndromes as well.