<prompt> About cetirizine all are true except-It is a 2nd generation anti histaminicIt is a metabolite of hydroxyzineGood CNS penetrationInhibits release of histamine  <response>: Ans. is c i.e., Good CNS penetration Cetrizine Cetrizine is a 2nd generation anti histaminic It is a metabolite of hydroxyzine with marked affinity for the peripheral H1 receptors, It penetrates CNS poorly and has mild sedating effect. It inhibits release of histamine from mast cells and therefore has been used for urticarial and atopic dermatitis. It is non - arrhythmogenic. 