DESLORATADINE
Clinical safety rating: safe
Animal studies have demonstrated safety
Desloratadine is a long-acting tricyclic histamine antagonist selective for the H1 receptor, inhibiting histamine release from mast cells and basophils. It reduces allergic inflammation by decreasing cytokine and chemokine release.
| Metabolism | Primarily metabolized by CYP2C8 and CYP3A4 to 3-hydroxydesloratadine; minor contribution from CYP2D6. |
| Excretion | Primarily renal (87% as metabolites, ~41% unchanged) and fecal (~9%). Metabolized to active 3-hydroxydesloratadine. |
| Half-life | Terminal half-life 27 hours (range 21–30 h) in healthy adults; supports once-daily dosing. |
| Protein binding | 82–87% bound to serum albumin. |
| Volume of Distribution | ~50 L/kg (approximately 0.6–0.7 L/kg) indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is approximately 65% (range 50–80%). |
| Onset of Action | Oral: 1 hour for symptom relief; intranasal: 30 minutes. |
| Duration of Action | 24 hours after oral dose; supports once-daily administration. |
| Molecular Weight | 310.82 |
| Action Class | Second-generation antihistamine (H1-receptor antagonist) |
5 mg orally once daily.
| Dosage form | TABLET |
| Renal impairment | GFR 30-50 mL/min: 5 mg every other day. GFR <30 mL/min or hemodialysis: 5 mg every third day. |
| Liver impairment | Mild to moderate hepatic impairment (Child-Pugh A or B): No adjustment required. Severe impairment (Child-Pugh C): 5 mg every other day. |
| Pediatric use | 6 months to 11 months: 1 mg orally once daily. 1 to 5 years: 1.25 mg orally once daily. 6 to 11 years: 2.5 mg orally once daily. ≥12 years: 5 mg orally once daily. |
| Geriatric use | No specific dose adjustment; use with caution due to potential age-related renal impairment; follow renal adjustment guidelines. |
| 1st trimester | Limited human data; animal studies show no risk. Use only if clearly needed. |
| 2nd trimester | No known risk in animal studies; human data limited. Use if benefit outweighs risk. |
| 3rd trimester | No known risk; monitor for neonatal withdrawal if used near term. |
Clinical note
No significant drug interactions at recommended doses Rarely may cause headache or somnolence.
| Placental transfer | Desloratadine crosses the placenta; data limited. |
| Breastfeeding | Desloratadine is excreted into breast milk in low amounts. Consider risk-benefit; alternative antihistamines with more data may be preferred. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Common Effects | urticaria |
| Serious Effects | Anaphylaxis, Angioedema, Severe cutaneous adverse reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis), Hepatotoxicity (elevated liver enzymes, hepatitis), Seizures, Tachycardia and palpitations, Hypersensitivity reactions |
Hypersensitivity to desloratadine or any ingredientSevere renal impairment (CrCl < 30 mL/min) - use caution, but not absolute
| Precautions | Use with caution in patients with severe renal impairment (CrCl <30 mL/min) or hepatic impairment., May cause drowsiness or fatigue; caution when driving or operating machinery., Caution in patients with a history of seizures or cardiac arrhythmias., Avoid concurrent use with alcohol or other CNS depressants. |
| Food/Dietary |
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| L2 |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: no adequate studies, potential risk unknown; animal studies show no teratogenicity. Second and third trimesters: no evidence of fetal harm in limited human data; use only if clearly needed. |
| Fetal Monitoring | Standard prenatal care; no specific fetal monitoring required. Monitor maternal response and adverse effects. |
| Fertility Effects | No known effect on human fertility; animal studies show no impairment of fertility at clinically relevant doses. |
| No significant food interactions. Avoid concurrent use with alcohol as it may increase CNS depression. |
| Clinical Pearls | Desloratadine is a long-acting, non-sedating antihistamine with minimal anticholinergic effects. It is indicated for allergic rhinitis and chronic idiopathic urticaria. Clinical pearls: Onset of action is within 1 hour; may cause mild headache or fatigue; does not significantly interact with CYP3A4 inhibitors; use with caution in renal impairment (CrCl <30 mL/min: dose every other day). |
| Patient Advice | Take once daily at the same time, with or without food. · Do not exceed recommended dose; may cause drowsiness in some patients, avoid driving if affected. · May take several days to achieve full effect for chronic symptoms. · If a dose is missed, take it as soon as remembered; if near the next dose, skip the missed dose. · Store at room temperature away from moisture and heat. |