Starches obtained from the grains of white fonio (Digitaria exilis) and tubers of sweet potato (Ipomea batatas) have been modified by acid hydrolysis at different steeping times – (0, 24 and 96 h) and the physicochemical, material and compaction properties of the modified starches have been evaluated in comparison with official corn starch. The effect of acid modification on the compaction properties of the starches were evaluated with the aim of determining their usefulness as excipients in direct compression. The results showed that the physicochemical and material properties of the starches varied considerably depending on their botanical source. Acid modification led to an increase in solubility and relative crystallinity but decrease in swelling and viscosity of the starches. The effects were found to depend on the steeping time during acid hydrolysis. The results of the compressional properties indicated that the starches formed intact tablets at relatively low compression pressure with acid modified starches forming tablets with higher tensile strength than the natural starches. The results indicate that the physicochemical and compaction properties of white fonio and sweet potato starches were improved by acid modification yielding starches that could be suitable as directly compressible excipient.

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The effects of plantain starch obtained from the unripe fruit of the plant Musa paradisiaca L. (Musaceae) on the mechanical and disintegration properties of paracetamol tablets have been investigated in comparison with the effects of corn starch BP using a 2 3 factorial experimental design. The individual and combined effects of nature of starch binder (N), concentration of starch binder (C), and the relative density of tablet (RD) on the tensile strength (TS), brittle fracture index (BFI), and disintegration time (DT) of the tablets were investigated. The ranking of the individual effects on TS was RD 9 C 99 N, on BFI was C 99 RD 9 N and on DT was N 9 C 9 RD. The ranking for the interaction effects on TS and DT was N-C 99 N-RD 9 C-RD, while that on BFI was N-C 99 C-RD 9 N-RD. Changing nature of starch from a "low" (plantain starch) to a "high" (corn starch) level, increasing the concentration of starch binding agent from 2.5% to 10.0% wt/wt, and increasing relative density of the tablet from 0.80 to 0.90, led to increase in the values of TS and DT, but a decrease in BFI. Thus, tablets containing plantain starch had lower tensile strength and disintegration time values than those containing corn starch, but showed better ability to reduce the lamination and capping tendency in paracetamol tablet formulation. The interaction between N and C was significantly (P G .001) higher than those between N and RD and between C and RD. There is therefore the need to carefully choose the nature (N) and concentration (C) of starch used as binding agent in tablet formulations to obtain tablets of desired bond strength and disintegration properties. Furthermore, plantain starch could be useful as an alternative binding agent to cornstarch, especially where faster disintegration is required and the problems of lamination and capping are of particular concern.

The effects of acid modification on the disintegrant properties of two native starches obtained from Digitaria exilis (white fonio) and Ipomea batatas (sweet potato) were evaluated in comparison with official corn starch in paracetamol tablet formulations. The starches were extracted from grains of white fonio and tubers of sweet potato, and modified by acid hydrolysis using 6% w/w hydrochloric acid for 48 h. The native and modified forms of the starches were employed as exo-disintegrants in paracetamol tablet formulations at concentrations of 2.5, 5.0, and 10.0% w/w. The disintegrant properties were assessed using crushing strength (C s ), friability (F r ), disintegration time (D T ), disintegrant efficiency ratio (DER), and the dimensionless quantity DER c . The results showed that crushing strength and friability of the tablets appeared to depend on the type, concentration, and nature of disintegrant used. Disintegration time generally decreased with increase in disintegrant concentration and the values complied with the pharmacopoeial standard for uncoated tablets ( 15 min). Tablets containing acid modified starches showed longer disintegration times than those containing the native starches although there were no significant differences (p > 0.05) in the values. Acid modification generally increased the disintegration efficiency ratio (DER) of the formulations while the values of DER c indicated that sweet potato starch would be the most efficient disintegrant with greater ability to enhance the balance between the mechanical and disintegration properties of the tablet. Thus, the experimental starches compared well with corn starch as disintegrants and could be useful for commercial tablet formulations.

A study has been made of the effects of pigeon pea starch obtained from the plant Cajanus cajan (L) Millisp. (family Fabaceae) and plantain starch obtained from the unripe fruit of Musa paradisiaca L. (family Musaceae) on the compressional, mechanical, and disintegration properties of paracetamol tablets in comparison with official corn starch BP. Analysis of compressional properties was done by using density measurements, and the Heckel and Kawakita equations, whereas the mechanical properties of the tablets were evaluated by using tensile strength (T--a measure of bond strength) and brittle fracture index (BFI--a measure of lamination tendency). The ranking for the mean yield pressure, P(y), for the formulations containing the different starches was generally corn < pigeon pea < plantain starch while the ranking for P(k), an inverse measure of the amount of plasticity, was pigeon pea < plantain < corn starch, which indicated that formulations containing corn starch generally exhibited the fastest onset of plastic deformation, whereas those formulations containing pigeon pea starch exhibited the highest amount of plastic deformation during tableting. The tensile strength of the tablets increased with increase in concentration of the starches while the Brittle Fracture Index decreased. The ranking for T was pigeon pea > plantain > corn starch while the ranking for BFI was corn > plantain > pigeon pea starch. The bonding capacity of the formulations was in general agreement with the tensile strength results. The disintegration time (DT) of the formulation increased with concentration of plantain and corn starches but decreased with concentration of pigeon pea starch. The general ranking of DT values was plantain < pigeon pea < corn starch. Notably, formulations containing pigeon pea starch exhibited the highest bond strength and lowest brittleness, suggesting the usefulness of pigeon pea starch in producing strong tablets with minimal lamination tendency. Plantain starch, on the other hand, would be more useful where faster disintegration of tablet is desired. The results show that the starches could be useful in various formulations depending on the intended use of the tablets with the implication that the experimental starches can be developed for commercial purposes.