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H1 antihistamines: current status and future directions
F Estelle R Simons1, Keith J Simons
1From the Departments of *Pediatrics and Child Health, **Immunology, ‡Canadian Institutes of Health Research National Training Program in Allergy and Asthma, §Faculty of Medicine, and ¶Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, Canada.
The World Allergy Organization Journal
|January 4, 2013
Summary
First-generation antihistamines can cause sedation due to crossing the blood-brain barrier. Second-generation antihistamines are preferred for allergies due to improved safety and efficacy profiles.
Area of Science:
- Pharmacology
- Allergy Treatment
Background:
- First-generation H1 antihistamines have been used for decades but lack optimal investigation.
- These older antihistamines readily cross the blood-brain barrier, leading to potential side effects like sedation and cognitive impairment.
Purpose of the Study:
- To compare and contrast the clinical pharmacology, efficacy, and safety of first-generation and second-generation H1 antihistamines.
- To identify the preferred H1 antihistamines for treating allergic conditions.
Main Methods:
- Review of existing literature on H1 antihistamine pharmacology, efficacy, and safety.
- Comparative analysis of first-generation and second-generation H1 antihistamines based on blood-brain barrier penetration and clinical data.
Main Results:
- First-generation antihistamines cross the blood-brain barrier, causing sedation and impairing cognitive and psychomotor performance.
- Second-generation antihistamines (e.g., cetirizine, loratadine) penetrate the blood-brain barrier less, with extensively studied pharmacology, efficacy, and safety.
Conclusions:
- Second-generation H1 antihistamines are the preferred choice for treating allergic rhinitis, allergic conjunctivitis, and urticaria.
- Future development may yield more advantageous H1 antihistamines through molecular techniques.
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