Mechanism of synergistic interactions and its influence on drug release from extended release matrices manufactured using binary mixtures of polyethylene oxide and sodium carboxymethylcellulose.

The ability of anionic polymer sodium carboxymethylcellulose to influence the release of four model cationic drugs (chlorpheniramine maleate, venlafaxine hydrochloride, propranolol hydrochloride and verapamil hydrochloride) from extended release (ER) hydrophilic matrices based on non-ionic polymer polyethylene oxide was investigated by X-ray photoelectron spectroscopy (XPS), isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). For all studied APIs, a combination of polyethylene oxide with sodium carboxymethylcellulose produced slower drug release compared to the matrices of single polymers. This behaviour was mainly attributed to the interaction of ester/carboxylic acid functionalities to yield H-bonding between the anionic polymer groups and the additionally protonated N-atoms of the active substances.

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.