Desloratadine

• Second-Generation H1 Antihistamine
• Selective peripheral H1 receptor inverse agonist
• Active metabolite of Loratadine

Parent class: Histamine & Antihistamines

Desloratadine selectively blocks peripheral H1 receptors.

Effects:

• ↓ Histamine-mediated vasodilation
• ↓ Capillary permeability
• ↓ Pruritus
• ↓ Sneezing and rhinorrhea

Characteristics:

• Minimal blood-brain barrier penetration
• Very low sedation risk
• Long duration of action

Loratadine is metabolized in the liver (CYP3A4, CYP2D6) to desloratadine.

Desloratadine:

• Is the active metabolite
• Does not require hepatic activation
• Has longer half-life
• Provides consistent 24-hour symptom control

Clinically:

• Similar efficacy to loratadine
• Slightly more predictable pharmacokinetics

• Oral administration
• Rapid absorption
• Duration: ~24 hours
• Primarily hepatic metabolism
• Eliminated via urine and feces

Minimal clinically significant CYP interactions at standard doses.

• Allergic Rhinitis
• Chronic idiopathic urticaria
• Seasonal allergic symptoms

Effective for:

• Sneezing
• Itching
• Rhinorrhea

Less effective for:

• Nasal congestion (intranasal corticosteroids superior)

• 5 mg PO once daily

Pediatric dosing based on age.

Generally well tolerated.

Possible:

• Headache
• Dry mouth
• Fatigue (rare)

Sedation:

• Very low
• Comparable to loratadine

• Severe hepatic impairment (monitor)
• Hypersensitivity

• Minimal clinically significant CYP interaction
• Low risk of QT prolongation

• Active metabolite of loratadine.
• Similar efficacy and safety profile to loratadine.
• Once-daily dosing.
• Low sedation risk.
• Marketing distinction more than major clinical difference from loratadine.

• Histamine & Antihistamines
• Loratadine
• Allergic Rhinitis – Stepwise Therapy