Polyvinylpyrrolidone as co-inhibitor of crystallization of nifedipine in paper tablets

Abstract

Techniques to maintain drugs amorphous that would otherwise crystallize is an extensively studied approach to enhance the dissolution characteristics of poorly soluble drugs. However, their performance is limited by the low physical stability of the amorphous phase which can lead to recrystallization which in turn results in decreased solubility and bioavailability of the drug. In this work, the crystallinity of nifedipine loaded into a cellulose-based paper matrix, so called smartFilms, was determined by terahertz time-domain spectroscopy. By adding polyvinylpyrrolidone as an extra carrier, the capability of smartFilms to transfer nifedipine into its amorphous state improved. Moreover, the performance of the formulation to inhibit recrystallization of the amorphous drug over a period of six months increased. For formulations containing up to 10 w% drug loading and additional polyvinylpyrrolidone (nifedipine/polyvinylpyrrolidone: 4:1 mass ratio), nifedipine was found to be completely amorphous after six months of storage.

Keywords: Amorphous drugs; Crystallinity; Nifedipine; Polyvinylpyrrolidone; Stability; Terahertz spectroscopy.