Pharmacology of Antihistamines

Pharmacology of Antihistamines

H1-antihistamines, the mainstay of treatment for urticaria, were developed from anticholinergic drugs more than 70 years ago. They act as inverse agonists rather than antagonists of histamine H1-receptors which are members of the G-protein family. The older first generation H1-antihistamines penetrate readily into the brain to cause sedation, drowsiness, fatigue and impaired concentration and m...

Comparative pharmacology of the H1 antihistamines.

SYMPOSIUM REPORT SUPPLEMENT Pharmacology of Antihistamines

This article reviews the molecular biology of the interaction of histamine with its H1-receptor and describes the concept that H1-antihistamines are not receptor antagonists but are inverse agonists i.e. they produce the opposite effect on the receptor to histamine. It then discourages the use of first-generation H1-antihistamines in clinical practice today for two main reasons. First, they are...

Molecular pharmacology of antihistamines in inhibition of oxidative burst of professional phagocytes.

Antihistamines of the H₁and H₃/H₄groups interfere with oxidative burst of human professional phagocytes in vitro. In the concentration of 10 μM, H₁antihistamines of the 1st and 2nd generation inhibited oxidative burst of human neutrophils in the rank order of potency: dithiaden > loratadine > brompheniramine > chlorpheniramine > pheniramine. Of the H₁antihistamines, the most effective was dithi...

Ambivalent antihistamines.

-In mice with a transplantable mammary carcinoma, treatment with the prostaglandin-synthesis inhibitors flurbiprofen or indomethacin produced various beneficial effects. Survival time after excision of the transplanted tumour was increased, particularly when the drugs were given with the chemotherapeutic agents methrotrexate and melphalan, and there were more disease-free survivors. The combine...