Adults

For Seasonal Allergic Rhinitis and Chronic Idiopathic Urticaria: 60 mg twice daily OR 120 mg or 180 mg once daily. For a 30 mg/5 mL suspension, 10 mL (60 mg) twice daily or 20 mL (120 mg) once daily.

Elderly

No specific dosage adjustment is generally required for elderly patients with normal renal function.

Pediatric

For Seasonal Allergic Rhinitis (2-11 years): 30 mg (5 mL of 30 mg/5 mL suspension) twice daily. For Chronic Idiopathic Urticaria (6 months to < 2 years): 15 mg (2.5 mL of 30 mg/5 mL suspension) twice daily. For Chronic Idiopathic Urticaria (2-11 years): 30 mg (5 mL of 30 mg/5 mL suspension) twice daily.

Renal_impairment

For adults with impaired renal function (CrCl ≤ 80 mL/min), the recommended initial dose is 60 mg once daily. For children with impaired renal function, a reduced initial dose is recommended based on age and severity of impairment; for example, 15 mg once daily for 6 months to <2 years and 30 mg once daily for 2-11 years.

Onset

Onset of action typically occurs within 1 hour.

Excretion

Primarily excreted unchanged, with about 80% eliminated in feces via biliary excretion and about 10% in urine.

Half life

The elimination half-life is approximately 11-15 hours.

Absorption

Rapidly absorbed from the gastrointestinal tract. Peak plasma concentrations are reached approximately 1-3 hours after oral administration. Bioavailability is about 33%.

Metabolism

Minimally metabolized; approximately 5% of the dose is metabolized, primarily by the liver.

Erythromycin & Ketoconazole

These drugs can increase fexofenadine plasma concentrations due to effects on P-glycoprotein, although this usually does not result in clinically significant side effects.

Antacids (Aluminum & Magnesium-containing)

Coadministration with aluminum- or magnesium-containing antacids can decrease fexofenadine absorption. Separate administration by at least 2 hours.