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Antihistaminic Activity (antihistaminic + activity)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Synthesis of Eosinophil Infiltration Inhibitors with Antihistaminic Activity.

CHEMINFORM, Issue 31 2003
Michiyo Gyoten
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

H1 -antihistaminic activity of cetirizine and fexofenadine in allergic children

PEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 3 2003
F. Estelle R. Simons
The clinical pharmacology of H1 -antihistamines has not yet been optimally studied in children and other special groups of patients. Our objective was to determine the onset, extent, and duration of H1 -antihistaminic activity of cetirizine and fexofenadine in the pediatric population. We performed a prospective, randomized, placebo-controlled, double-blind, crossover, single-dose study of these H1 -antihistamines in 15 allergic children, mean±SEM age 8.8±0.5 years. We used suppression of the histamine-induced wheal and flare as the primary outcome. Compared with pre-dose baseline, cetirizine 10 mg suppressed the wheals significantly (p,0.05) from 2 to 24 h and the flares significantly from 1 to 24 h, achieving 77±SEM 10% to 86±9% suppression of the wheal from 2 to 7 h and 85±6% to 88±6% suppression of the flare from 2 to 24 h, inclusive. Compared with baseline, fexofenadine 30 mg did not suppress the wheals or flares significantly at any time, achieving 40±9% to 54±9% wheal suppression from 2 to 7 h and 45±11% to 68±9% flare suppression from 2 to 7 h, inclusive. Compared with placebo, cetirizine suppressed the wheals and flares significantly from 2 to 24 h. Compared with placebo, fexofenadine suppressed the wheals significantly at 4 and 6 h, and the flares from 4 to 7 h. Cetirizine suppressed the wheals and flares significantly more than fexofenadine at 2 h (wheals), and at 3 and 24 h (flares). Placebo did not suppress the wheals and flares significantly at any time. In children age 6,11 years, cetirizine 10 mg has a rapid onset of H1 -antihistaminic activity, a 24-h duration of action, and greater H1 -activity than fexofenadine 30 mg. Higher doses of fexofenadine should be tested in children. [source]

Clinical pharmacology of the H1 -receptor antagonists cetirizine and loratadine in children

PEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 2 2000
F. Estelle R. Simons
H1 -receptor antagonists are widely used in children but are not as well-studied in children as they are in adults. Our objective was to determine the onset and duration of action and the relative potency of the H1 -receptor antagonists cetirizine and loratadine in children. We performed a prospective, randomized, placebo-controlled, double-blind, crossover, single-dose study of cetirizine and loratadine using suppression of the histamine-induced wheal and flare as the primary outcome. In 15 allergic children, mean age 9 years, compared with baseline, cetirizine (10 mg) suppressed the wheals and flares significantly from 0.25 to 24 h, achieving nearly 100% of flare suppression from 2 to 24 h, inclusive, and loratadine (10 mg) suppressed the wheals and flares significantly from 0.75 to 24 h, inclusive. Cetirizine suppressed the wheals and flares significantly more than loratadine from 0.25 to 1 h, inclusive, and at 0.5, 1, 2, 3, 5, 6, 7, and 24 h, respectively. Placebo also suppressed the wheal and flare significantly at some assessment times. Cetirizine and loratadine both have excellent antihistaminic activity in children, with a rapid onset of action and a 24-h duration of action in this population. [source]

A Comparison of the Effects of Olopatadine and Ketotifen on Model Membranes

ACTA OPHTHALMOLOGICA, Issue 2000
Howard Brockman
ABSTRACT. Olopatadine is a human conjunctival mast cell stabilizer with anti-histaminic activity. Ketotifen is an older molecule that possesses antihistaminic activity and is reported to have additional pharmacological properties. The interactions of these two compounds with model membranes (i.e., monolayers of 1-stearoyl-2-oleoyl-sn-glycerophosphocholine at the argon-buffer interface), and natural (i.e., erythrocyte) membranes were compared in an effort to understand the differences in their biological activities. Drug-lipid interaction with monolayers was determined by monitoring the surface pressure as a function of the drug concentration in the aqueous phase supporting the monolayer. Drug interaction with erythrocyte membranes was determined by monitoring changes in the permeability of the membranes to hemoglobin and 6-carboxyfluorescein as a function of drug concentration in the medium. Olopatadine and ketotifen are both intrinsically surface active and both interact with phospholipid monolayers. However, in both the presence and absence of lipid monolayers, the changes in surface pressure induced by olopatadine are lower than those caused by ketotifen. The effects of these two drugs on cell membranes were dramatically different. Exposure of bovine erythrocytes to increasing concentrations of ketotifen (1,10 mM) resulted in complete hemolysis of the cells, whereas olopatadine (1,10 mM) caused only minimal hemolysis (<8%). Consistent results were obtained in experiments measuring the leakage of 6-carboxyfluorescein from erythrocyte ghosts as a more sensitive marker of membrane perturbation. Olopatadine treatment (0.1,10 mM) minimally perturbed the cell membrane while ketotifen (1,10 mM) caused a concentration dependent release of the fluorescent marker. These data demonstrate fundamental differences between the two drugs in their effects on cell membranes. Moreover, the differences are consistent with the surface activities of the two compounds measured in monolayers and with reported differences in their pharmacological activities. These findings offer an explanation for the biphasic non-specific cytotoxic effect of ketotifen on histamine release from mast cells and may account for the non-lytic mast cell stabilizing activity of olopatadine. [source]