CHILDREN'S FEXOFENADINE HYDROCHLORIDE HIVES
Clinical safety rating: safe
Aluminum and magnesium-containing antacids decrease absorption Rarely may cause headache or drowsiness.
Fexofenadine is a peripheral H1-receptor antagonist that selectively inhibits histamine-mediated effects on H1 receptors, reducing allergic symptoms. It does not penetrate the blood-brain barrier significantly, minimizing sedation.
| Metabolism | Minimally metabolized; 5% undergoes hepatic metabolism via CYP3A4; 95% excreted unchanged in feces (80%) and urine (11-12%). |
| Excretion | Fexofenadine is primarily excreted unchanged in feces (approximately 80%) via biliary elimination, with minimal renal excretion (approximately 11%). It is not metabolized by the liver. |
| Half-life | Terminal elimination half-life is approximately 14.4 hours (range 11–15 hours) in healthy adults. This supports once-daily dosing. Half-life may be prolonged in patients with renal impairment (up to 19 hours). |
| Protein binding | Fexofenadine is approximately 60–70% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Volume of distribution (Vd) is approximately 5.4–5.8 L/kg, indicating extensive tissue distribution and binding to peripheral tissues. |
| Bioavailability | Oral bioavailability is approximately 33% (range 25–40%), likely due to incomplete absorption and first-pass intestinal efflux by P-glycoprotein. Bioavailability is unaffected by food. |
| Onset of Action | Onset of action for oral tablets or suspension is within 1 hour. Maximal effect on histamine-induced wheal and flare is observed by 2–3 hours. |
| Duration of Action | Duration of action for antihistamine effect (suppression of wheal and flare) is approximately 24 hours, supporting once-daily dosing. Clinical relief of allergic symptoms may persist for 24 hours. |
| Molecular Weight | 501.8 |
| Action Class | Second-generation antihistamine (piperidine derivative) |
Adults and children 12 years and older: 180 mg orally once daily or 60 mg orally twice daily.
| Dosage form | TABLET |
| Renal impairment | For GFR <15 mL/min: Avoid use; for GFR 15-30 mL/min: 60 mg once daily; for GFR >30 mL/min: No adjustment needed. |
| Liver impairment | No specific adjustments recommended for mild to moderate hepatic impairment (Child-Pugh A or B); severe impairment (Child-Pugh C) has not been studied. |
| Pediatric use | Children 6 months to <2 years: 15 mg orally twice daily; 2 to <12 years: 30 mg orally twice daily; 12 years and older: adult dose. |
| Geriatric use | No specific adjustment required; monitor for adverse effects due to potential renal impairment; consider starting at lower end of dosing range. |
| 1st trimester | Limited data; no known teratogenicity; avoid if possible. |
| 2nd trimester | Limited data; no known fetal risk; use only if clearly needed. |
| 3rd trimester | Limited data; no known fetal risk; use only if clearly needed. |
Clinical note
Aluminum and magnesium-containing antacids decrease absorption Rarely may cause headache or drowsiness.
| FDA category | Animal |
| Placental transfer | Minimal; low molecular weight suggests some transfer but limited data. |
| Breastfeeding | Excreted into breast milk in low amounts; unlikely to cause adverse effects in infant; use with caution. |
■ FDA Black Box Warning
None
| Common Effects | urticaria |
| Serious Effects | Anaphylaxis, Angioedema, Severe cutaneous adverse reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis), Hypersensitivity reactions |
Hypersensitivity to fexofenadine or any component
| Precautions | Avoid use in patients with severe renal impairment (CrCl <15 mL/min) due to limited data, Use with caution in patients with hepatic impairment, Not recommended in children under 2 years of age, Potential for increased risk of adverse effects with concomitant use of drugs affecting transporters (e.g., OATP, P-gp) |
| Food/Dietary | Fruit juices such as apple, orange, and grapefruit decrease fexofenadine absorption by up to 36%; avoid coadministration. Administer with water only. Antacids containing aluminum or magnesium reduce absorption; separate by at least 2 hours. No other significant food interactions. |
Loading safety data…
| Lactation Rating | L2 |
| Teratogenic Risk | Pregnancy Category C. Insufficient human data; animal studies show no teratogenicity at doses up to 3 times MRHD. First trimester: Avoid unless benefit outweighs risk. Second/third trimester: No known specific risks; limited data. |
| Fetal Monitoring | No specific monitoring required. Standard prenatal care. Monitor for maternal adverse effects (e.g., drowsiness, dizziness) and fetal heart rate if concerns. |
| Fertility Effects | No known adverse effects on fertility. Animal studies show no impairment at doses up to 3 times MRHD. |
| Clinical Pearls | Fexofenadine is a non-sedating second-generation antihistamine indicated for chronic idiopathic urticaria. Onset of action is within 1 hour, peak effect at 2-3 hours. Does not cross blood-brain barrier significantly, thus minimal sedation. No QT prolongation at recommended doses. Contraindicated in severe renal impairment (CrCl <30 mL/min) due to reduced clearance; use lower dose (30 mg once daily for children). Tablet and oral suspension bioequivalence not established; do not interchange. Avoid coadministration with fruit juices (apple, orange, grapefruit) which decrease absorption by up to 36%; use water only for administration. Antacids containing aluminum and magnesium reduce absorption; separate by at least 2 hours. Not recommended in children under 2 years. |
| Patient Advice | Take this medication exactly as prescribed, usually twice daily for hives. · Do not take with fruit juices (apple, orange, grapefruit); use plain water only. · If you take antacids containing aluminum or magnesium, separate by at least 2 hours. · This medication may cause drowsiness in rare cases; avoid driving if affected. · Store at room temperature away from moisture and heat. · Do not exceed the recommended dose; overdose may cause severe drowsiness. · If symptoms persist or worsen, contact your healthcare provider. · Shake the oral suspension well before each use. |