====== Desloratadine ======

===== Classification =====
  * Second-Generation H1 Antihistamine
  * Selective peripheral H1 receptor inverse agonist
  * Active metabolite of [[allergy:drugs:loratadine|Loratadine]]

Parent class: [[allergy:histamine|Histamine & Antihistamines]]

----

===== Mechanism of Action =====

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

----

===== Pharmacologic Background =====

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

----

===== Pharmacokinetics =====

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

Minimal clinically significant CYP interactions at standard doses.

----

===== Indications =====

  * [[allergy:clinical:allergic_rhinitis|Allergic Rhinitis]]
  * Chronic idiopathic urticaria
  * Seasonal allergic symptoms

Effective for:
  * Sneezing
  * Itching
  * Rhinorrhea

Less effective for:
  * Nasal congestion (intranasal corticosteroids superior)

----

===== Dosing (Adult) =====

  * 5 mg PO once daily

Pediatric dosing based on age.

----

===== Adverse Effects =====

Generally well tolerated.

Possible:
  * Headache
  * Dry mouth
  * Fatigue (rare)

Sedation:
  * Very low
  * Comparable to loratadine

----

===== Contraindications / Cautions =====

  * Severe hepatic impairment (monitor)
  * Hypersensitivity

----

===== Drug Interactions =====

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

----

===== Clinical Pearls =====

  * 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.

----

===== Comparison Within Class =====

^ Drug ^ Sedation Risk ^ Elimination ^ Unique Feature ^
| [[allergy:drugs:loratadine|Loratadine]] | Very low | Hepatic (CYP3A4) | Prodrug |
| [[allergy:drugs:desloratadine|Desloratadine]] | Very low | Hepatic | Active metabolite |
| [[allergy:drugs:cetirizine|Cetirizine]] | Low | Renal | Racemic mixture |
| [[allergy:drugs:levocetirizine|Levocetirizine]] | Low | Renal | R-enantiomer |
| [[allergy:drugs:fexofenadine|Fexofenadine]] | Minimal | Renal/Fecal | Least sedating |

----

===== Related Pages =====

  * [[allergy:histamine|Histamine & Antihistamines]]
  * [[allergy:drugs:loratadine|Loratadine]]
  * [[allergy:clinical:allergic_rhinitis|Allergic Rhinitis – Stepwise Therapy]]