Quantitative chemical profiling of cellulose acetate excipient via C NMR spectroscopy in controlled release formulations.

Cellulose acetate (CA) is the main component of controlled-release (CR) coating of formulations such as osmotic-controlled release oral delivery system (OROS) and CR microspheres. Despite multiple applications, there are limited or no reports dealing with the characterization and quantification of CA in the formulated systems. Thus, the present investigation deals with the development of the Quantitative Carbon-13 Nuclear Magnetic Resonance (qCNMR) spectroscopy method for the determination of CA amount in the CR microsphere formulations. The developed qCNMR method was also verified using control CA samples from marketed OROS formulation. Thereafter, the concentration of CA in the microspheres was calculated. Furthermore, the impact of different concentrations of CA on the critical quality attributes such as the drug release profile from the formulation was investigated. The study demonstrated the CA coating levels to be inversely proportional to the extent and rate of release of API. The developed qCNMR method was found to be accurate and precise and can be explored further to investigate the effect of different stability conditions on the degree of polymerization and degradation of CA resulting in altered quality of pharmaceutical products.