Effect of pregelatinization and carboxymethylation on starches from African rice and Fonio: Influence on release of low melting-point drug Starch modifications for drug release

Adebisi Adeola,Waseem Kaialy,Omobolanle A Omoteso,Kofi Asare-Addo,Michael Ayodele Odeniyi

doi:10.5920/bjpharm.645

Adebisi Adeola, Waseem Kaialy + Show 3 more

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https://doi.org/10.5920/bjpharm.645

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Abstract

The study investigated theeffect of modification on the physicochemical and drug release properties ofstarches extracted from African rice (Oryzaglaberrima Steud) (AR) and Fonio (Digitariaexilis Stapf) (FR). The starches were modified by pregelatinization andcarboxymethylation. The morphology andphysicochemical properties of the produced grades of starches were analysedusing SEM, RVA, FTIR, P-XRD and DSC. Dissolution was also conducted using amodel poorly-soluble drug with low melting point (Ibuprofen). SEM images showeda distinct change in the morphology of the modified starches. Native starchforms had the highest solubility while the carboxymethylated starch forms hadthe highest water absorbing capacity and swelling index. FTIR and P-XRDconfirmed the characteristic functional groups of the starches with theirthermal properties demonstrated by DSC. Ibuprofen release from the starch tabletsin phosphate buffer (pH 6.8) showed that native AR starch demonstrated similarrelease profiles with its carboxymethylated form (f2 = 57.5), however, different from the pregelatinisedform (f2 = 32.8). Native FRstarch demonstrated a different release profile to the carboxymethylated (f2 = 8.6) and the pregelatinisedstarch forms (f2 = 35.3). Fickiandiffusion was the main kinetics of drug release. Modification of these starchescan generate polysaccharides with different properties and improvedfunctionalities with a potential for use as alternative pharmaceuticalexcipients.

Highlights

In recent years, there has been increased interest in the search for polymers, which are biodegradable, biocompatible and show low or non-toxicity in the development of novel pharmaceutical drug carriers (Nep et al, 2017, 2018)
Degree of substitution of Carboxymethylated starch The total degree of substitution (DS) is the average number of functional groups introduced in the polymer and this mainly determines the properties of the carboxymethylated products (Spychaj et al, 2013)
The sharp edged polygonal shape is as a result of vigorous starch biosynthesis, which leads to the tight packing of the granules in the kernel (Newman et al, 2007) and is typical of horny starches such as rice (Fujita and Nakamura, 2015)

Summary

Introduction

There has been increased interest in the search for polymers, which are biodegradable, biocompatible and show low or non-toxicity in the development of novel pharmaceutical drug carriers (Nep et al, 2017, 2018). Several methods have been used to modify starch in order to obtain desirable properties such as enhanced solubility and texture to broaden its commercial applications (Kittipongpatana et al, 2006; Odeniyi et al, 2011, 2017) Physical modification methods such as pregelatinisation/heat treatment (Thomas and Atwell, 1999) and chemical methods such as etherification (Misman et al, 2015), esterification (Winkler et al, 2013), cross-linking (Zhou et al, 2016), grafting (Setty et al, 2014) and hydrolysis (Roman et al, 2017) have been reported. Carboxymethylated starches produce pastes that have a smoother texture, greater flexibility and mechanical strength than pregelatinised starch (Mishra et al, 1991)

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