Is fexofenadine better than cetirizine?

Fexofenadine vs. Cetirizine: Comparative Efficacy and Side Effect Profile

Fexofenadine is better than cetirizine primarily due to its superior side effect profile, with significantly less sedation at recommended doses while maintaining equivalent efficacy for allergic symptoms. 1

Efficacy Comparison

• Both medications demonstrate similar efficacy in treating allergic rhinitis symptoms 2, 3
• In clinical trials, fexofenadine 120mg once daily was shown to be as effective as cetirizine 10mg once daily in reducing overall symptoms of seasonal allergic rhinitis 2
• Both medications effectively relieve:
  • Sneezing
  • Rhinorrhea
  • Itchy nose, palate, or throat
  • Itchy, watery, or red eyes

Side Effect Profile Differences

Sedation

• Fexofenadine does not cause sedation at recommended doses or even at higher than FDA-approved doses 1
• Cetirizine is associated with sedative properties compared to placebo 1
  • Mild drowsiness reported in 13.7% of cetirizine users versus 6.3% with placebo 1
  • In direct comparison studies, patients receiving fexofenadine experienced significantly less drowsiness than those receiving cetirizine 3

Performance Impairment

• Fexofenadine does not cross the blood-brain barrier, making it free of sedative effects even at dosages up to 240 mg/day 4
• Cetirizine has been associated with performance impairment at 10mg or higher doses in some studies 1

Duration of Action

• Both medications are suitable for once-daily administration 4
• Some studies suggest cetirizine may have a longer duration of antihistaminic effect in the skin 5
• However, both provide 24-hour symptom relief when used at recommended doses 4, 2

Special Considerations

Renal Impairment

• In moderate renal impairment, cetirizine dose should be halved 1
• Cetirizine should be avoided in severe renal impairment 1

Older Adults

• Fexofenadine is preferable in older adults who are more sensitive to psychomotor impairment and at increased risk for falls 6

Drug Interactions

• Fexofenadine has minimal cardiac effects and does not inhibit cardiac K+ channels 4
• Fexofenadine is not associated with QT prolongation even when combined with erythromycin or ketoconazole 4

Clinical Decision Algorithm

1. For most patients with allergic rhinitis:

   • Choose fexofenadine as first-line therapy due to equivalent efficacy with less sedation

2. Consider cetirizine when:

   • Patient has previously responded well to it without sedation
   • Cost is a significant factor (cetirizine may be less expensive)

3. Avoid cetirizine and prefer fexofenadine in:

   • Patients who need to drive or operate machinery
   • Elderly patients
   • Patients with history of sedation with antihistamines
   • Patients with moderate-to-severe renal impairment

Dosing

• Fexofenadine: 180mg once daily or 60mg twice daily
• Cetirizine: 10mg once daily

In conclusion, while both medications demonstrate similar efficacy in controlling allergic symptoms, fexofenadine offers a clear advantage in terms of reduced sedation and cognitive impairment, making it the preferred choice for most patients requiring antihistamine therapy.