The influence of sodium carboxymethylcellulose on drug release from polyethylene oxide extended release matrices.

Anionic polymer sodium carboxymethylcellulose (CELLOGEN® HP-HS and/or HP-12HS) was investigated for its ability to influence the release of three model drugs propranolol hydrochloride, theophylline and ibuprofen from polyethylene oxide (POLYOX™ WSR 1105 and/or Coagulant) hydrophilic matrices. For anionic ibuprofen and non-ionic theophylline, no unusual/unexpected release profiles were obtained from tablets containing a mixture of two polymers. However, for cationic propranolol HCl, a combination of polyethylene oxide (PEO) with sodium carboxymethylcellulose (NaCMC) produced a significantly slower drug release compared to the matrices with single polymers. The potential use of this synergistic interaction can be a design of new extended release pharmaceutical dosage forms with a more prolonged release (beyond 12 h) using lower polymer amount, which could be particularly beneficial for freely water-soluble drugs, preferably for once daily oral administration. In order to explain changes in the obtained drug release profiles, Fourier transform infrared absorption spectroscopy was performed. A possible explanation for the more prolonged propranolol HCl release from matrices based on both PEO and NaCMC may be due to a chemical bond (i.e. ionic/electrostatic intermolecular interaction) between amine group of the cationic drug and carboxyl group of the anionic polymer, leading to a formation of a new type/form of the active (i.e. salt) with sustained release pattern.