Levocetrizine

Levocetrizine is the (R)-enantiomer of cetirizine, featuring a substituted piperidine ring fused to a chlorophenyl group via an ether linkage, with an esterified carboxylic acid moiety at the terminal carbon. Its structure includes a tertiary amine and a methoxy substituent on the aromatic ring, conferring enhanced selectivity for peripheral H1-receptors compared to its racemic counterpart. The compound exists as a single enantiomer, synthesized via chiral resolution or asymmetric synthesis, and is utilized as an HPLC reference standard for quantifying levocetrizine in pharmaceutical formulations.