CHILDREN'S FEXOFENADINE HYDROCHLORIDE ALLERGY
Clinical safety rating: safe
Aluminum and magnesium-containing antacids decrease absorption Rarely may cause headache or drowsiness.
Fexofenadine is a selective peripheral H1-receptor antagonist. It inhibits histamine release from mast cells and basophils, reducing allergic symptoms.
| Metabolism | Minimally metabolized; primarily excreted unchanged in feces (80%) and urine (11%). CYP3A4 and CYP2D6 contribute to minor metabolism. |
| Excretion | Primarily fecal (80%) and renal (11%) as unchanged drug. |
| Half-life | 14.4 hours (range 11-16 hours) in healthy adults; prolonged in renal impairment. |
| Protein binding | 60-70%, primarily to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 5.4-5.8 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is approximately 33% due to first-pass metabolism. |
| Onset of Action | 1-2 hours after oral administration. |
| Duration of Action | Approximately 24 hours, allowing once-daily dosing. |
Fexofenadine hydrochloride 60 mg orally twice daily or 180 mg orally once daily.
| Dosage form | TABLET |
| Renal impairment | For GFR 15-59 mL/min: 60 mg orally once daily. For GFR <15 mL/min or hemodialysis: 30 mg orally once daily. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe impairment (Child-Pugh C). |
| Pediatric use | 6 months to <2 years: 15 mg orally twice daily. 2 to <12 years: 30 mg orally twice daily. ≥12 years: same as adult. |
| Geriatric use | Initiate at 60 mg orally once daily; may increase to 60 mg twice daily based on response and tolerance. Monitor for increased sedation or dizziness. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Aluminum and magnesium-containing antacids decrease absorption Rarely may cause headache or drowsiness.
| FDA category | Animal |
| Breastfeeding | Fexofenadine is excreted into breast milk in small amounts; the milk-to-plasma ratio is approximately 0.4. The drug is considered compatible with breastfeeding based on low transfer and lack of adverse effects in infants. Caution is advised when used in nursing mothers due to potential for sedation in infants. |
| Teratogenic Risk |
■ FDA Black Box Warning
None.
| Common Effects | urticaria |
| Serious Effects |
Hypersensitivity to fexofenadine or any component of the formulation.
| Precautions | Renal impairment (dose adjustment required); hypersensitivity reactions; rare cases of hepatitis; use with caution in elderly. |
| Food/Dietary | Avoid concomitant intake of fruit juices (apple, grapefruit, orange) as they reduce fexofenadine absorption by up to 36%. Take with water only. Avoid taking with high-fat meals; may slightly delay absorption. |
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| FDA Pregnancy Category C. In animal studies, no teratogenic effects were observed at doses up to 3 times the maximum recommended human dose. However, there are no adequate and well-controlled studies in pregnant women. Fexofenadine should be used during pregnancy only if clearly needed. First trimester: Theoretical risk due to antihistamine use, but no specific data. Second and third trimesters: No known fetal risks. |
| Fetal Monitoring | No specific monitoring required beyond routine prenatal care. Observe for maternal adverse effects such as sedation, dizziness, or dry mouth. No fetal monitoring indicated. |
| Fertility Effects | No known effect on fertility. Animal studies have not shown impaired fertility at clinically relevant doses. |
| Clinical Pearls | Fexofenadine is a second-generation antihistamine with low CNS penetration; sedation is rare. Onset of action is within 1 hour, duration ~24 hours. Use with caution in renal impairment (CrCl <80 mL/min): start at 30 mg daily. Not significantly metabolized by CYP450; few drug interactions. Avoid concurrent use with aluminum/magnesium-containing antacids (separate by at least 2 hours). |
| Patient Advice | Take this medication on an empty stomach, at least 1 hour before or 2 hours after a meal. · Do not take with fruit juices (apple, grapefruit, orange) as they decrease absorption; take with water only. · Do not exceed the recommended dose; double-check the product labeling for children's dosing based on weight and age. · This medication may cause drowsiness in some patients, though less than older antihistamines; use caution when driving or operating machinery until you know how it affects you. · Store at room temperature, away from moisture and heat. |