Abstract
Objective: This work focused on evaluating the micromeritic and compressional properties of pregelatinized African water yam (Discorea alata) starch and its modified forms with comparison to pregelatinized corn starch and microcrystalline cellulose.Methods: Two modifications of the water yam starch were prepared; acetone dehydrated pregelatinized form (DSA) and an admixture of DSA and pregelatinized corn starch (CDSA). A third form of starch is the acetone dehydrated pregelatinized corn starch (CSA). These were used to form batches compacted as tablets using diclofenac sodium as the active moiety. Physicochemical and flow characteristics of the starch powders were elucidated, and the drug starch compatibility studies done using the Fourier transform Infra-red (FTIR) technique. Compaction studies were investigated on tablets formed at different compression pressures and Heckel plots were prepared.Results: The slope of the straight line (K) of 0.8959 was greatest for F1 while yield pressure (Py) value of 10.965 was highest for F3. These values from the Heckel plot suggest that while the tablets of control batch of microcrystalline cellulose (F4) and a batch of pregelatinized corn starch (F2) formed harder compacts, less likely deformed plastically, the Discorea alata batch (F1) and the admixed batch (F3) were likely to deform plastically. Also, the binding efficiency of the compact was significantly high (47.81%Kgscm-1) for F4 at 56.5Kpas compaction pressure, higher than that obtainable for any of the other formulations at the compaction pressures under consideration. All starches formed had similar moisture content (of 10%) despite the different sources but the interaction between the water molecule and pregelatinized water yam starch improved as revealed by viscosity(7.18mPas), hydration capacity(3.27%) and swelling index (250%) of CDSA.Conclusion: It could be concluded that pregelatinized water yam starch could be used as a substitute for corn starch or microcrystalline cellulose as a pharmaceutical excipient (binder/filler) in tablets formulation.
Highlights
Research questions prompting innovative thinking are constantly on the minds of researchers and manufacturers of excipients. Such questions as; what is likely the ideal excipient with greater degree of functionality to go for? Will the approval of such adjuvant by the relevant regulatory authorities be a very tall order? How can an existing excipient be improved upon to achieve better dosage forms? No doubt, the search for excipients having improved properties is in no way meagre since the desires and convenience of patients are intended to be achieved in dosage form design, while not compromising therapeutic efficacy
Acetone (BDH Chemicals, UK), cornstarch, water yam starch, distilled water, all other chemicals being of analytical grade
Values are presented as mean±standard deviation (SD)
Summary
Research questions prompting innovative thinking are constantly on the minds of researchers and manufacturers of excipients. The search for excipients having improved properties is in no way meagre since the desires and convenience of patients are intended to be achieved in dosage form design, while not compromising therapeutic efficacy. Starches obtained from different sources vary in their respective constitution. Using equations such as Kawakita’s and Heckel’s and their interpretations, pharmaceutical excipients could be studied and differentiated into plastic or brittle materials. The yield pressure in Heckel plot is used as the determining factor [1] Such knowledge is essential to achieve compacts having the good tensile strength and binding efficiency. Native starch has desirable disintegration properties but its crystalline characteristics give it its poor water solubility [2]
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