{2-Hydr-oxy-3-[4-(2-methoxy-ethyl)-phen-oxy]prop-yl}isopropyl-ammonium hemisuccinate.

Metoprolol, a widely used adrenoreceptor blocking drug, is commonly administered as the succinate or tartrate salt. The structure of metoprolol succinate, C(15)H(26)NO(3) (+)·0.5C(4)H(4)O(4) (2-), is characterized by the presence of ribbons in which cations, generated by N-protonation of the metoprolol mol-ecules, are hydrogen bonded to succinate anions. The dicarboxylic acid transfers its H atoms to two metoprolol mol-ecules; the asymmetric unit contains one cation and half an anion, the latter possessing twofold rotational symmetry. There are localized nets of O-H⋯O and N-H⋯O hydrogen bonds along a ribbon, within centrosymmetric arrangements formed by pairs of metoprolol cations and pairs of anions, each of the latter contributing with one of its carboxyl groups to the localized net. This arrangement is repeated along the ribbon by the operation of the twofold axis bis-ecting the anion, as well as by the lattice translation.