From the Guidelines
Fexofenadine (Allegra) is the preferred non-drowsy allergy medication that does not cause QT interval prolongation, with a typical adult dose of 180mg once daily. Several non-drowsy allergy medications that don't typically cause QT prolongation include loratadine (Claritin), cetirizine (Zyrtec), and desloratadine (Clarinex) 1. These second-generation antihistamines are generally considered safe for people concerned about QT interval prolongation. According to the guidelines for evaluation and management of urticaria in adults and children, cetirizine, desloratadine, fexofenadine, levocetirizine, loratadine, and mizolastine are licensed for urticaria in the U.K. 1. However, mizolastine is contraindicated in clinically significant cardiac disease and when there is prolongation of the Q-T interval, making it an unsuitable option for patients with QT prolongation concerns 1.
Key Considerations
- Fexofenadine has the least potential for cardiac effects and minimal sedation, making it a preferred option 1.
- The typical adult dose is 180mg once daily for fexofenadine, 10mg once daily for loratadine and cetirizine, and 5mg once daily for desloratadine.
- These medications work by blocking histamine receptors without significantly crossing the blood-brain barrier, which is why they cause less drowsiness than older antihistamines.
- It's essential to note that while these medications are generally considered safe regarding QT prolongation, anyone with heart conditions or taking other medications should consult with their healthcare provider before starting any new medication, as individual factors and drug interactions can affect safety 1.
Important Safety Information
- Patients with renal impairment should avoid certain medications, such as acrivastine, which should be avoided in moderate renal impairment (creatinine clearance 10–20 mL min) 1.
- Patients should be offered the choice of at least two nonsedating H1 antihistamines because responses and tolerance vary between individuals 1.
From the FDA Drug Label
No differences in adverse events or QTc interval were observed when subjects were administered fexofenadine hydrochloride alone or in combination with either erythromycin or ketoconazole The non-drowsy allergy medication fexofenadine does not cause QT interval prolongation, as indicated by the lack of differences in QTc interval observed in studies 2.
- Key points:
- Fexofenadine hydrochloride was administered alone or in combination with erythromycin or ketoconazole
- No differences in QTc interval were observed
- Fexofenadine is a non-drowsy allergy medication
- The medication is prescribed for the relief of symptoms of seasonal allergic rhinitis or chronic idiopathic urticaria (hives)
From the Research
Non-Drowsy Allergy Medications
Non-drowsy allergy medications that do not cause QT interval prolongation include:
- Loratadine 3, 4, 5, 6
- Cetirizine 3, 4, 5, 6
- Fexofenadine 3, 4, 5, 7
- Desloratadine 5, 7, 6
- Levocetirizine 7, 6
- Bilastine 7
- Rupatadine 7
Mechanism of QT Interval Prolongation
The cardiotoxic effects of some nonsedating antihistamines are due to the inhibition of repolarization potassium channels, particularly IKr, which leads to prolongation of the action potential and QT interval, and the development of early after-depolarization, which triggers torsades de pointes (TdP) 3.
Safety Considerations
Patients at risk of developing TdP, such as those with congenital long QT syndrome, cardiac disease, liver disease, electrolyte disturbance, or those taking drugs that can prolong QT interval, should avoid nonsedating antihistamines that are also capable of prolonging the QT interval 3, 7. Caution is needed when using loratadine in patients with risk factors for torsades de pointes or who are taking certain enzyme inhibitors 6. Cetirizine should be avoided in cases of renal failure 6.