Pharmacologic Screening of Antihistamine Drugs

Classification and Recommendations

Second-generation antihistamines are the recommended initial treatment for pharmacology practical screening of antihistaminic drugs due to their superior safety profile and reduced sedative effects compared to first-generation antihistamines, as recommended by the American Academy of Allergy, Asthma, and Immunology 1
First-generation antihistamines have significant potential to cause sedation, performance impairment, and anticholinergic effects, and should be avoided as first-line therapy due to safety concerns and potential for impairment 1
The American College of Allergy, Asthma, and Immunology recommends second-generation antihistamines for allergic conditions due to their better safety profile 1

Begin with second-generation antihistamines due to better safety profile, prioritizing non-sedating options first (fexofenadine, loratadine, desloratadine) 1
Compare antihistamines based on sedative properties at recommended doses, time to maximum concentration, duration of action, and potential for drug interactions 1, 2
Cetirizine has the shortest time to maximum concentration, and desloratadine has the longest elimination half-life at 27 hours 2

For hepatic impairment, avoid mizolastine and use loratadine and desloratadine with caution, as recommended by the British Association of Dermatologists 2
For renal impairment, avoid acrivastine and reduce doses of cetirizine and levocetirizine 2
For pregnancy, generally avoid all antihistamines if possible, especially in the first trimester, according to the British Journal of Dermatology 2

Compare efficacy for specific symptoms (rhinorrhea, sneezing, itching, congestion) 1
Assess anticholinergic effects, such as dry mouth and urinary retention 1

Loratadine and desloratadine are generally non-sedating at recommended doses, and patients should be offered at least two non-sedating options as responses vary between individuals 1, 2
Intranasal antihistamines may be considered for first-line treatment of allergic and non-allergic rhinitis, and have a clinically significant effect on nasal congestion 1