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Research Article

On the plasticizing properties of divalproex sodium: physicochemical and spectroscopic characterization studies

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Pages 455-464 | Received 19 Nov 2017, Accepted 16 Aug 2018, Published online: 06 Nov 2018
 

Abstract

The objective of the research was to demonstrate the plasticization properties of divalproex sodium, due to its component—valproic acid, on ethyl cellulose, which could prove beneficial for film fabrications or hot melt extrusion based formulations. Films containing 10–50% w/w (DVS/EC) as dry weight were prepared using solvent evaporation method and characterized using texture analyzer, hybrid rheometer, differential scanning calorimetry, thermogravimetry, X-ray diffractometry, polarized microscopy, FTIR, and Raman spectroscopy. It was found that there was a decrease in average peak load, melt viscosity, and glass transition temperature (Tg) while increase in elongation, with increase in concentration of DVS in the films. These results demonstrate the plasticization tendency of DVS on EC, which was attributed to the presence of valproic acid (fatty acid) in DVS. XRD studies showed amorphous nature of the films; however, polarized microscopy revealed the presence of scattered undissolved sodium valproate crystals. The presence of a single Tg established complete miscibility between valproic acid and EC. Films showed reasonable physical stability (similar Tg) at 45 °C/75% RH for 2 weeks (open condition), attributable to the similar solubility parameters of DVS and EC. FTIR and Raman spectroscopy results proved the presence of hydrogen bonding between DVS and EC.

Acknowledgements

The authors express their heartfelt thanks to Dr. Abu Serajuddin, Dr. Suhas Gumaste, and St. John’s University to allow use of their lab facilities for this work. The authors acknowledge Rutgers University for providing research facilities and G&W PA Laboratories for providing financial assistance and research facilities to carry out this research.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by St. John's University.