An investigation of the adsorption of hydroxypropylmethyl cellulose 2910 5 mPa s and polyvinylpyrrolidone K90 around Naproxen nanocrystals

Abstract

The selection of the appropriate stabilizer for a nanosuspension is still based on trial-and-error and the amount of stabilizer is mostly determined as the lowest amount that results in a stable nanosuspension. Although nanosuspensions are often dried, it is currently not known if the stabilizer remains associated with the surface after drying. Hence, the purpose of this study was to investigate the association of two common pharmaceutical stabilizers [hydroxypropylmethyl cellulose (HPMC) 2910 5 mPa s and polyvinylpyrrolidone (PVP) K90] with the surface of Naproxen crystals. The association between drug and polymer after drying was investigated by evaluating the mixing glass transition temperature using modulated differential scanning calorimetry. Dynamic laser scattering was used to study the Naproxen-polymer association in suspension state. Association with the Naproxen surface was proven after drying for both polymers. A difference in behavior between HPMC and PVP was observed at the liquid-particle interface. In suspension state, the HPMC layer continuously increases in thickness when adding more polymer, whereas in contrast for PVP, the surface can become saturated. The conclusion is that the behavior in suspension determines the behavior of the stabilizer after drying and it is governed by the physicochemical properties of the polymers.