These agents are selective peripheral H1 receptor inverse agonists with minimal central nervous system penetration.
Primary use:
| Drug | Usual Adult Dose | Sedation Risk | Elimination | Unique Feature |
|---|---|---|---|---|
| Loratadine | 10 mg daily | Very low | Hepatic (CYP3A4) | Prodrug |
| Desloratadine | 5 mg daily | Very low | Hepatic | Active metabolite |
| Cetirizine | 10 mg daily | Low | Renal | Active metabolite of hydroxyzine |
| Levocetirizine | 5 mg daily | Low | Renal | R-enantiomer refinement |
| Fexofenadine | 180 mg daily | Minimal | Renal/Fecal | Least sedating |
(Note: All far less sedating than first-generation agents.)
If daytime alertness is critical: Fexofenadine
If patient has hepatic impairment: Cetirizine or Levocetirizine
If patient has renal impairment: Loratadine or Desloratadine
If chronic urticaria: Cetirizine commonly effective