Material and tablet properties of pregelatinized (thermally modified) Dioscorea starches

Published Date
September 2008, Vol.70(1):357–371, doi:10.1016/j.ejpb.2008.04.011

Research paper

Title 

Material and tablet properties of pregelatinized (thermally modified) Dioscorea starches

• Author 

• Oluwatoyin A. Odeku ^a,b
• Wolfgang Schmid ^a
• Katharina M. Picker-Freyer ^a,,

• aDiv. of Pharmaceutics and Biopharmaceutics, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany
• bDepartment of Pharmaceutics and Industrial Pharmacy, University of Ibadan, Ibadan, Nigeria

Received 19 December 2007. Revised 16 April 2008. Accepted 17 April 2008. Available online 24 April 2008

Abstract

The material and tablet formation properties of pregelatinized (thermally modified) forms of four Dioscorea starches have been investigated. Dioscorea starches were pregelatinized followed by either oven drying (PS) or freeze drying (FD) and used as excipient in direct compression. The physicochemical, morphological and material properties of the pregelatinized starches have been investigated. The tablet formation properties were assessed using the 3-D modeling parameters, the Heckel equation and the force–displacement profiles. The tablet properties were evaluated using the elastic recovery, compactibility plots and the disintegration test. The results indicate that pregelatinization improved the compressibility and flowability of the Dioscoreastarches. The high bulk and tap densities of PS coupled with their good flowability offer a unique possibility of the starches being used as filler in capsule formulations. The modified starches generally showed differences in their time and pressure dependent deformation behaviour. PS exhibited higher elasticity during tableting. FD Chinese and FD Bitter showed higher plasticity and low fast elastic deformation than the PS forms of the starches indicating that the FD starches undergo the highest plastic deformation. However, FD starches generally showed higher compactibility compared to the PS forms of the Dioscorea starches. While FD White and FD Water showed fast disintegration time and high compactibility, FD Chinese and FD Bitter were non-disintegrating and showed high compactibility. The high compactibility observed with the FD starches appears to be as a result of material change occurring during tableting probably due to the effect of temperature or pressure or a combination of both factors. Thus, FD White and FD Water starches could be useful when high crushing force and fast disintegration are of concern while FD Chinese and FD Bitter, which were non-disintegrating, could find application as excipients for controlled drug delivery.

Keywords

• Pregelatinized starch
• Material properties
• Tableting
• Dioscorea starches
• Yam

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  Corresponding author. Institute of Pharmacy, Div. of Pharmaceutics and Biopharmaceutics, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle/Saale, Germany. Tel.: +49 345 552 5138; fax: +49 345 552 7029.

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