1. Cetirizine and Loratadine: A Comparison Using the ED50in Skin Reactions
- Author
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Ramboer, I, Bumbacea, R, Lazarescu, D, and Radu, JR
- Abstract
To quantify objectively the comparative potencies of the antihistamines, loratadine and cetirizine, we determined the dose that inhibits histamine-induced skin reactions by 50% of the maximum response (ED50) for each drug. Cetirizine at 2.5, 5 or 10 mg, loratadine at 10, 20 or 40 mg or placebo were given to 14 healthy female subjects in a randomized double-blind crossover design. Inhibition of the wheal and flare response to the histamine prick test (10, 100 and 500 mg/ml) was evaluated. Depending on the histamine concentrations, the ED50for wheals were in the ranges 4.3–4.7, 2.1–2.2 and 1.7–1.9 mg cetirizine, 2, 4 and 6 h after dosing, respectively. For loratadine, the ED50for wheals were in the ranges 35.6 – > 40, 9.1–24.1 and 9.1–13.9 mg, 2, 4 and 6 h after dosing, respectively. Calculation of the ED50demonstrated that, on average, cetirizine is seven to nine times more potent than loratadine at inhibiting wheal and flare reactions.
- Published
- 2000
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