Propranolol hydrochloride-anionic polymer binding interaction.

Three different anionic polymers namely Eudragit S 100, Eudragit L 100-55 (methacrylic acid copolymers), and sodium carboxymethylcellulose (NaCMC) were used to evaluate the propranolol hydrochloride-anionic polymer interaction. The physical and chemical properties of propranolol hydrochloride and anionic polymer complex were investigated using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The DSC profiles demonstrated that the characteristic peak of propranolol hydrochloride cannot be found in the heating curve of the complexes, indicating that complex is different in physicochemical properties from the physical mixture of drug-polymer. The FTIR spectra also confirmed that there is an interaction between propranolol hydrochloride and methacrylic acid copolymers. The binding of the drug to the polymers was due to the existence of preferential hydrogen bonding between the amino group of the propranolol hydrochloride and the carboxylic functions of the polymers and that pH conditions can influence this binding.