<prompt> Which is not a 2nd generation anti-histaminic agent?CetirizineCyclizineLoratidineFexofenadine  <response>: Ans B CyclizineRef: Goodman and Gilman 12the p921,922Antihistaminics may be classified into first generation and second generation compounds on the basis of CNS penetration and anticholinergic properties. First Generation Anti-histaminics can penetrate blood brain barrier and possess additional anticholinergic properties which are lacking in second generation drugs. Cyclizine is a first generation whereas cetirizine, loratadine and fexofenadine are second generation drugs. 