LORATADINE REDIDOSE
Clinical safety rating: safe
No significant drug interactions at recommended doses Rarely may cause headache or somnolence.
Selective peripheral H1 receptor antagonist; inhibits histamine release from mast cells.
| Metabolism | Hepatic via CYP3A4 and CYP2D6; active metabolite desloratadine. |
| Excretion | Renal (approximately 40% as metabolites), biliary/fecal (approximately 60% as metabolites). Less than 1% excreted unchanged in urine. |
| Half-life | Terminal elimination half-life is 8–14 hours (mean ~12 hours) for desloratadine (active metabolite); parent loratadine half-life ~3–20 hours (mean ~8 hours). Clinically, once-daily dosing maintains steady state in 5–7 days. |
| Protein binding | Loratadine: ~97% bound to plasma proteins (albumin and alpha-1-acid glycoprotein). Desloratadine: ~82–87% bound. |
| Volume of Distribution | Loratadine: Vd ~119 L (approximately 1.7 L/kg for a 70 kg adult). Desloratadine: Vd ~338 L (approximately 4.8 L/kg). Indicates extensive tissue distribution. |
| Bioavailability | Oral bioavailability is not well-defined due to extensive first-pass metabolism; absolute bioavailability is approximately 45–60% for loratadine. Desloratadine has high oral bioavailability (>80%). |
| Onset of Action | Oral: Onset of antihistaminic effect occurs within 1–3 hours, with maximal effect at 4–6 hours. |
| Duration of Action | Duration of action is approximately 24 hours, allowing once-daily dosing. Clinical effect persists beyond 24 hours in some patients. |
| Molecular Weight | 382.88 |
| Action Class | Second-generation antihistamine (H1-receptor antagonist) |
10 mg orally once daily
| Dosage form | TABLET, ORALLY DISINTEGRATING |
| Renal impairment | No adjustment required for GFR ≥10 mL/min. For GFR <10 mL/min, use every other day dosing (10 mg every 48 hours). |
| Liver impairment | Child-Pugh Class A: 10 mg orally once daily. Child-Pugh Class B or C: 10 mg orally every other day. |
| Pediatric use | Children 2–5 years: 5 mg orally once daily. Children ≥6 years: 10 mg orally once daily. |
| Geriatric use | No specific adjustment required; use with caution due to potential for increased anticholinergic effects and renal impairment. Start at 10 mg orally once daily. |
| 1st trimester | Limited human data; animal studies show no fetal harm. Use only if clearly needed. |
| 2nd trimester | No evidence of malformations; generally considered low risk. |
| 3rd trimester | Low risk; no known adverse effects near term. |
Clinical note
No significant drug interactions at recommended doses Rarely may cause headache or somnolence.
| FDA category | Animal |
| Placental transfer | Loratadine crosses the placenta in animal studies; human data limited but likely similar. |
| Breastfeeding | Loratadine is excreted into breast milk in small amounts. Infant dose estimated <1% of maternal weight-adjusted dose. No adverse effects reported in nursing infants. |
■ FDA Black Box Warning
None.
| Common Effects | urticaria |
| Serious Effects | Anaphylaxis, Angioedema, Hepatic failure, Severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome and toxic epidermal necrolysis, Tachyarrhythmias (rare, especially with overdose or in patients with prolonged QT interval) |
Hypersensitivity to loratadine or any component of the formulation
| Precautions | Use with caution in patients with hepatic or renal impairment; avoid in acute asthma attacks; potential for somnolence (rare at recommended doses). |
| Food/Dietary | No significant food interactions. May be taken with or without food. Grapefruit juice does not significantly affect loratadine metabolism. |
Loading safety data…
| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | Loratadine is categorized as FDA Pregnancy Category B. No teratogenic effects have been observed in animal studies, and no well-controlled studies in pregnant women. There is no evidence of increased risk of major birth defects in first trimester exposure based on human data. |
| Fetal Monitoring | No specific monitoring required beyond routine prenatal care. Monitor pregnant women with severe hepatic impairment (Child-Pugh class C) as clearance may be reduced. |
| Fertility Effects | No known adverse effects on human fertility. Loratadine did not impair fertility in animal studies at doses up to 20 times the human dose. |
| Clinical Pearls | Loratadine RediDose is a rapidly disintegrating tablet formulation for patients with difficulty swallowing. Onset of action is within 1-3 hours. It is a non-sedating antihistamine with minimal anticholinergic effects. Reduce dose in hepatic impairment (Child-Pugh score 5-6: 10 mg every other day). Not recommended in severe renal impairment (CrCl <10 mL/min). |
| Patient Advice | Place the tablet on the tongue; it dissolves without water. Take orally once daily with or without food. · Avoid exceeding 10 mg daily for adults and children ≥6 years. Do not use for children <6 years unless directed by a doctor. · May cause drowsiness or dizziness; avoid driving until you know how the drug affects you. · If symptoms persist >1 week or worsen, consult a healthcare provider. · Inform your doctor if you have liver or kidney disease, or if you are pregnant or breastfeeding. |