CLARINEX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CLARINEX (CLARINEX).
Desloratadine is a long-acting tricyclic histamine antagonist with selective peripheral H1-receptor antagonist activity. It inhibits histamine release from mast cells and reduces allergic inflammation.
| Metabolism | Extensively metabolized in the liver via glucuronidation and to a lesser extent via CYP2D6 and CYP3A4 to active metabolite 3-hydroxydesloratadine. |
| Excretion | Desloratadine is primarily eliminated via renal excretion (~40% as metabolites) and fecal elimination (~45% as metabolites). Less than 2% is excreted unchanged in urine. |
| Half-life | Terminal elimination half-life is approximately 27 hours (range 20-30 hours). This long half-life supports once-daily dosing and allows for steady-state concentrations within 7 days. |
| Protein binding | 83-87% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Approximately 49 L/kg (range 36-62 L/kg). The large Vd indicates extensive tissue distribution beyond the vascular space. |
| Bioavailability | Absolute bioavailability is not determined due to lack of intravenous formulation. Oral absorption is rapid and complete, with no significant first-pass metabolism; relative bioavailability is considered high. |
| Onset of Action | Oral: Onset of action occurs within 1-2 hours, with peak plasma concentrations reached at approximately 3 hours. Clinical effect on histamine-induced wheal and flare is evident by 2 hours. |
| Duration of Action | Duration of action is at least 24 hours, allowing for once-daily administration. Suppression of wheal and flare persists for >24 hours after a single dose. |
| Molecular Weight | 310.82 |
| Action Class | Macrolides |
| Brand Substitutes | Plugclar 500mg Injection, Clariglan 500mg Injection, Cefrithro Injection, Clarineon 500mg Injection, Clary 500mg Injection, Clinopak 600mg Injection, Clinzucia 600mg Injection, Clindol 600mg Injection, Egyclin 600mg Injection, Clindum 600mg Injection |
5 mg orally once daily.
| Dosage form | Tablet |
| Renal impairment | GFR 30-50 mL/min: 5 mg every 48 hours; GFR <30 mL/min or ESRD: 5 mg every 48 hours. |
| Liver impairment | Child-Pugh A: 5 mg every 48 hours; Child-Pugh B or C: 5 mg every 48 hours. |
| Pediatric use | 6-11 months: 1 mg orally once daily; 12-23 months: 1.25 mg orally once daily; 2-5 years: 1.25 mg orally once daily; 6-11 years: 2.5 mg orally once daily; ≥12 years: 5 mg orally once daily. |
| Geriatric use | No specific dose adjustment recommended; use with caution due to potential increased sensitivity. |
| 1st trimester | Desloratadine is generally avoided in the first trimester due to lack of sufficient human data; animal studies have not shown fetal harm, but caution is advised. |
| 2nd trimester | Limited human data suggest low risk; use only if clearly needed. |
| 3rd trimester | Limited data; may cause irritability in neonates if used near term, but generally considered low risk. |
Clinical note
Comprehensive clinical and safety monograph for CLARINEX (CLARINEX).
| Placental transfer | Desloratadine crosses the placenta; studies indicate fetal levels are approximately 50% of maternal plasma levels. |
| Breastfeeding | Desloratadine is excreted into breast milk in low amounts (estimated relative infant dose <2% of maternal weight-adjusted dose). Adverse effects in infants are unlikely, but caution is recommended due to lack of long-term studies. |
■ FDA Black Box Warning
None.
| Serious Effects | Anaphylaxis, Angioedema, Severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome and toxic epidermal necrolysis, Hepatotoxicity, Seizures, QT prolongation (rare) |
Hypersensitivity to desloratadine or any component of the formulationSevere renal impairment (CrCl <10 mL/min) for the syrup formulation containing sorbitol
| Precautions | Use with caution in patients with hepatic or renal impairment; dose adjustment recommended., May cause somnolence or fatigue; patients should avoid driving or operating machinery until they know how the drug affects them., Avoid use in patients with known hypersensitivity to desloratadine or loratadine. |
| Food/Dietary | No significant food interactions. Grapefruit juice does not alter desloratadine pharmacokinetics. Alcohol may potentiate sedation in some individuals. |
Loading safety data…
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | FDA Pregnancy Category C. Animal studies (rats, rabbits) at doses up to 210 mg/kg/day (approximately 210 times the human AUC at recommended dose) showed no teratogenicity but increased preimplantation loss and decreased implantation. No adequate human studies. Use only if benefit outweighs risk. First trimester: limited data, theoretical risk; avoid unless necessary. Second and third trimesters: no known specific risks, but caution due to limited data. |
| Fetal Monitoring | Monitor maternal blood pressure and heart rate. Assess for sedation, dizziness. Fetal monitoring not specifically required; however, in case of maternal overdose or adverse effects, fetal heart rate monitoring may be considered. No specific fetal ultrasound or nonstress test mandated. |
| Fertility Effects | No human fertility studies. In animal studies (rats), desloratadine at oral doses up to 24 mg/kg/day (approximately 210 times human AUC) showed no effect on fertility or reproductive performance. No known impairment in humans based on postmarketing data. |
| Clinical Pearls | Desloratadine (CLARINEX) is a non-sedating antihistamine; onset of action within 1 hour; no significant anticholinergic effects; dose adjustment in renal impairment (CrCl <30 mL/min: 5 mg every other day); efficacy may be reduced in patients with hepatic impairment; does not prolong QTc at usual doses; grapefruit juice does not affect pharmacokinetics. |
| Patient Advice | Take once daily with or without food. · Do not exceed recommended dose; may cause drowsiness in some patients, avoid driving if affected. · Store at room temperature away from moisture and heat. · Inform your doctor if you have kidney or liver disease. · Do not use for immediate relief of asthma symptoms. |