From the Guidelines
No, terfenadine is not used in the US due to its potential to cause serious cardiac side effects, particularly life-threatening heart rhythm abnormalities. The use of terfenadine has been restricted in most countries, including the US, where it was withdrawn from the market in 1998 by the FDA 1. This decision was made due to the risk of QT prolongation and torsades de pointes, especially when terfenadine is co-administered with certain medications, such as ketoconazole or macrolide antibiotics, that inhibit its metabolism by the CYP 3A4 isoenzyme 1. Some key points to consider when evaluating the use of terfenadine include:
- The potential for terfenadine to block cardiac K+ channels and prolong repolarization, leading to an increased risk of arrhythmias 1
- The risk of toxic levels of terfenadine when its metabolism is impaired by co-administration of certain medications or substances, such as grapefruit juice 1
- The availability of safer alternative antihistamines, such as fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec), and desloratadine (Clarinex), which do not carry the same cardiac risks as terfenadine. It is essential for patients who previously used terfenadine to consult with their healthcare provider about appropriate antihistamine alternatives to ensure their safety and well-being.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Terfenadine Usage in the US
- Terfenadine is a second-generation antihistamine that was widely prescribed for allergic and upper respiratory diseases 2.
- However, due to its potential to cause life-threatening ventricular arrhythmias, its use has been limited 3, 4.
- Studies have shown that terfenadine can prolong the QT interval and cause torsades de pointes, a potentially fatal ventricular arrhythmia 3, 4, 5.
- As a result, terfenadine is no longer recommended for use in the US due to its potential cardiotoxic effects 3, 4.
- Other second-generation antihistamines, such as loratadine and cetirizine, are considered safer alternatives and are still widely used in the US 3, 4.
Regulatory Status
- The US FDA has issued warnings about the potential cardiotoxic effects of terfenadine and has recommended that it be used with caution 3, 4.
- Terfenadine is no longer marketed in the US due to its potential risks 3, 4.
- However, it may still be available in some countries or through online pharmacies, and patients should be aware of its potential risks and benefits before using it 6.