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. |
| Molecular Weight | 501.9 |
| Action Class | Second-generation antihistamine (piperidine derivative) |
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 | Limited human data; animal studies show no evidence of harm. Use only if clearly needed. |
| 2nd trimester | No known risk; usual antihistamine precautions apply. Consider as alternative to older antihistamines. |
| 3rd trimester | No known risk near term; avoid excessive doses. Not associated with uterine contractions. |
Clinical note
Aluminum and magnesium-containing antacids decrease absorption Rarely may cause headache or drowsiness.
| FDA category | Animal |
| Placental transfer | Placental transfer is likely based on molecular weight and limited studies; exact degree not well quantified. |
| Breastfeeding |
■ FDA Black Box Warning
None.
| Common Effects | urticaria |
| Serious Effects | Anaphylaxis, Angioedema, Severe cutaneous adverse reactions (e.g., Stevens-Johnson syndrome), Hypersensitivity reactions, Cardiac arrhythmias (rare, primarily with overdose or pre-existing QT prolongation) |
Hypersensitivity to fexofenadine or any component of the formulationSevere renal impairment (CrCl <10 mL/min) - contraindicated due to lack of data
| 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. |
Loading safety data…
| Fexofenadine is excreted into breast milk in low amounts; unlikely to cause adverse effects in nursing infants. Use with caution, especially in neonates. Weigh benefits against potential risks. |
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | 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. |