Characterization and evaluation of acid-modified starch of Dioscorea oppositifolia (Chinese yam) as a binder in chloroquine phosphate tablets

Adenike Okunlola,Oluwatomi Akingbala

doi:10.1590/s1984-82502013000400009

Adenike Okunlola, Oluwatomi Akingbala

Open Access

https://doi.org/10.1590/s1984-82502013000400009

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Abstract

Chinese yam (Dioscorea oppositifolia) starch modified by acid hydrolysis was characterized and compared with native starch as a binder in chloroquine phosphate tablet formulations. The physicochemical and compressional properties (using density measurements and the Heckel and Kawakita equations) of modified Chinese yam starch were determined, and its quantitative effects as a binder on the mechanical and release properties of chloroquine phosphate were analyzed using a 2³ full factorial design. The nature (X1), concentration of starch (X2) and packing fraction (X3) were taken as independent variables and the crushing strength-friability ratio (CSFR), disintegration time (DT) and dissolution time (t80) as dependent variables. Acid-modified Chinese yam starch showed a marked reduction (p<0.05) in amylose content and viscosity but increased swelling and water-binding properties. The modified starch had a faster onset and greater amount of plastic flow. Changing the binder from native to acid-modified form led to significant increases (p<0.05) in CSFR and DT but a decrease in t80. An increase in binder concentration and packing fraction gave similar results for CSFR and DT only. These results suggest that acid-modified Chinese yam starches may be useful as tablet binders when high bond strength and fast dissolution are required.

Highlights

MATERIAL AND METHODSThe use of starches as natural polymers for pharmaceutical applications remains attractive because they are cheap, readily available, biodegradable and capable of modification (Lawal et al, 2007; Yiu et al, 2008; Okunlola et al, 2010)
Packing fraction (X3) appears to interact with all the variables. This is expected as X3 had the largest individual effect on the mechanical property (CSFR) and release (DT) of the tablets. These results suggest that acid modified Chinese yam starch may be a better binder than native starch, providing greater mechanical strength but faster dissolution of tablets
These results show that increasing the binder type and concentration of the tablets would increase crushing strength–friability ratio (CSFR) and disintegration time (DT)

Summary

MATERIAL AND METHODS

The use of starches as natural polymers for pharmaceutical applications remains attractive because they are cheap, readily available, biodegradable and capable of modification (Lawal et al, 2007; Yiu et al, 2008; Okunlola et al, 2010). The relative efficacy of acid-modified Chinese yam starch as a binding agent in tablet formulations for pharmaceutical use has not been assessed. The suitability of acid modified starch of Dioscorea oppositifolia (Chinese yam) as binding agent in chloroquine tablet formulation was determined in comparison to the native form of the starch. Py was inversely related to the ability of the formulation to deform plastically under pressure and was greater for native than for acid-modified Chinese yam starch, indicating that the latter showed faster onset of plastic deformation during compression than the native form. The combination of the two methods usually provides a more accurate analysis of the compaction behavior of TABLE IV - Factorial design for the formulation and evaluation of batches

B2 B3 B4 B5 B6 B7 B8

Findings

CONCLUSION