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Tigernut starch has been isolated and modified by forced retrogradation of the acidic gel by freezing and thawing processes. Relevant physicochemical and functional properties of the new excipient (tigernut starch modified by acid gelation and accelerated (forced) retrogradation (ST(AM))) were evaluated as a direct compression excipient in relation to the native tigernut starch (ST(NA)), intermediate product (tigernut starch modified by acid gelation (ST(A))), and microcrystalline cellulose (MCC). The particle morphology, swelling capacity, moisture sorption, differential scanning calorimeter (DSC) thermographs and X-ray powder diffraction (XRD) patterns, flow, dilution capacity, and tablet disintegration efficiency were evaluated. The particles of ST(NA) were either round or oval in shape, ST(A) were smooth with thick round edges and hollowed center while ST(AM) were long, smooth, and irregularly shaped typically resembling MCC. The DSC thermographs of ST(NA) and MCC showed two endothermic transitions as compared with ST(A) and ST(AM) which showed an endothermic and an exothermic. The moisture uptake, swelling, flow, and dilution capacity of ST(AM) were higher than those of MCC, ST(A), and ST(NA). The XRD pattern and moisture sorption profile of ST(AM) showed similarities and differences with ST(NA), ST(A), and MCC that relate the modification. Acetylsalicylic acid (ASA) tablets containing ST(AM) disintegrated at 3±0.5 min as compared with the tablets containing ST(NA), ST(A), and MCC which disintegrated at 8.5±0.5, 10±0.5, and 58±0.8 min, respectively. The study shows the physicochemical properties of tigernut starch modified by forced retrogradation as well as its potential as an efficient direct compression excipient with enhanced flow and disintegration abilities for tablets production.

Purpose: To characterize some preformulation properties of aqueous stem bark extract of Bridelia ferruginea Benth (Euphorbiaceae) (BF). Methods: The stem bark was extracted by maceration in hot distilled water. Two batches of granules containing the extract were prepared by wet granulation using maize starch, polyvinylpyrrolidone (PVP), Avicel® PH-101, magnesium stearate, acacia and lactose as excipients. Some physicochemical and micromeritic properties of the powdered extract and granules were determined following standard procedures. Results: The pH of the aqueous BF extract was 5.4 ± 0.1 while the moisture content of the dry extract was 12.0 %. Total ash value of the extract was 7.91 ± 0.03. Particle size increased after granulation from 228 to 531 µm in the order: granules 1 > granules 2 > powder. The bulk and tapped densities decreased significantly (p < 0.05) from 0.40 ± 0.04 to 0.77 ± 0.09 and 0.49 ± 0.05 to 0.85 ± 0.09 g/ml, respectively in the order: granules 2 < granules 1 < powder. Similarly, the angle of repose increased after granulation from 24.0 ± 0.5 to 25.4 ± 0.9 o in the order: granules 2 < granules 1 < powder (p < 0.05). The flow rate and compressibility of the granules (2.45 ± 0.08 g/min and 0.17, respectively) improved significantly (p < 0.05) over those of the powdered BF extract (2.34 ± 0.05 g/min and 0.26, respectively). Conclusion: The results of this preformulation study indicates that the powdered extract of Bridelia ferruginea possesses properties that make it suitable for its formulation into standard solid dosage forms. [ABSTRACT FROM AUTHOR]