The methanol disolvate and the dihydrate of fexofenadine, an antihistamine drug

Fexofenadine [systematic name: (±)-(4-{1-hydroxy-4-[4- (hydroxydiphenylmethyl)piperidinium-1-yl]-buty1}phenyl)-2-methylpropionate], crystallizes in two forms, viz. as the methanol disolvate, C₃₂H ₃₉NO₄·2CH₄O, and as the dihydrate, C₃₂H₃₉NO₄·2H₂O. It exists in the two structures as a zwitterion, which self-assembles as dimers sustained by a pair of charged-assisted N-H⋯OOC hydrogen bonds. In the methanol disolvate, the supramolecular organization consists of discrete fexofenadine dimers solvated by four molecules of methanol. The dihydrate structure is sustained by a more extended hydrogen-bonding scheme, wherein the hydrated dimeric entities are interlinked by additional hydrogen bonds. The fexofenadine molecule adopts different and differently disordered conformations of the 1-hydroxybutyl residue in the two structures.