Advances in H 1 -Antihistamines

Histamine has an important role as a chemical messenger in physiologic responses, neurotransmission, allergic inflammation, and immunomodulation by way of the H1-receptor. Most H1-antihistamines, which are useful in treating these effects, possess similar efficacy in allergic rhinoconjunctivitis and chronic urticaria. However, there are clinically relevant differences among them in their pharmacology and safety profiles.