Evaluation of Colloidal Solid Dispersions: Physiochemical Considerations and In Vitro Release Profile
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Research Article Evaluation of Colloidal Solid Dispersions: Physiochemical Considerations and In Vitro Release Profile Vaibhav I. Patel1 and Rutesh H. Dave1,2
Received 13 August 2012; accepted 25 February 2013; published online 15 March 2013 Abstract. Colloidal solid dispersion is an innovative breakthrough in the pharmaceutical industry that overcomes the solubility-related issue of poorly soluble drugs by using an amorphous approach and also the stability-related issue by means of a complex formation phenomenon using different carrier materials. In the present study, a newly developed adsorption method is introduced to incorporate a high-energy sulfathiazole–polyvinylpyrrolidone (Plasdone® K-29/32) solid dispersion on porous silicon dioxide (Syloid® 244FP). Different ternary systems of sulfathiazole–Plasdone® K-29/32–Syloid® 244FP were prepared (1:1:2, 1:1:3, and 1:2:2) and categorized depending on the mechanism by which Syloid® 244FP was incorporated. Modulated differential scanning calorimetry (MDSC), X-ray diffraction, Fourier transform infrared spectroscopy, and in vitro dissolution studies were conducted to characterize the ternary systems. The X-ray diffraction and MDSC data showed a lack of crystallinity in all internal and external ternary systems, suggesting a loss of the crystallinity of sulfathiazole compared to the physical mixtures. USP apparatus II was used to measure the in vitro dissolution rate of the prepared systems at 75 rpm in different media. The dissolution rate of the optimum ratio (1:2:2) containing an internal ternary solid dispersion system was found to be three times higher than that of the external and physical systems. Thus, the porous silicon dioxide incorporated into the conventional binary solid dispersion acted as a carrier to disperse the complex and increase the dissolution rate. KEY WORDS: amorphous; colloidal solid dispersion; FTIR; porous silicon dioxide; ternary solid dispersion.
INTRODUCTION Recent data suggest that approximately 40% of the marketed active pharmaceutical ingredients (API’s) and 90% of the new chemical entities (NCE’s) under development are classified as Biopharmaceutics Classification System (BCS) class II (high permeability and low solubility) and class IV (low permeability and low solubility) drugs, suggesting issues associated with solubility and ultimately bioavailability in situ (1). Since the concept of bioavailability came into existence, it became clear that, when a drug is administered orally, it has to first dissolve in the alimentary tract fluid, and the rate of this dissolution becomes a fundamental factor for the rate of absorption (2). The rate of solution is the ratedetermining step for the bioavailability of orally administered poorly water-soluble drugs (3). Various methods are available for improving the rate of dissolution, including salt formation, Electronic supplementary material The online version of this article (doi:10.1208/s12249-013-9947-z) contains supplementary material, which is available to authorized users. 1
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