Dynamic and structural features of N-Isopropyl-N- {3-[4(4-Methoxybenzoylamino)Phenoxy]-2-Hydroxypropyl} Ammonium Chloride in [2H6]DMSO were investigated by measuring13C and1H spin-lattice relaxation rates and13C- {1H} and1H- {1H} n.O.e. Correlation times for main and internal reorientational motions were interpreted in terms of internal rotation around the two planal axes. Selective and double-selective1H spin-lattice relaxation rates were measured, wherefrom relevant proton-proton intramolecular distances were calculated. It was shown that the β1− blocking agent assumes a preferred conformation where extensive intramolecular H-bonding prevents segmental motion along the quaternary ammonium sidechain.