The study of dimensional changes in the tablets was carried out for 5 h in distilled water (see Table V). As the proportion
of dried mucilage increased, the radial and axial swelling of the tablet increased. When the drug–mucilage ratio was at its
lowest (1:0.5), the swelling of the tablet was at its lowest. As the ratio increased, the radial and axial swelling increased
proportionally. There was more swelling of the tablet in the axial direction compared with the radial direction.
Table V: Radial and axial swelling of tablets in distilled water.
The dried mucilage was evaluated as a matrix-forming material for oral sustained-released tablets using diclofenac sodium
as a model drug. Matrix tablets, each containing 100 mg of diclofenac sodium, were prepared using dried mucilage in various
drug–mucilage ratios (1:0.5, 1:1, 1:1.5, and 1:2). An ideal modified-release dosage form should release a loading dose (20–25%)
in the first hour. Later, the remaining drug should be released at a constant rate over an extended period. An ideal release
pattern was calculated according to these criteria. The in vitro dissolution profiles are shown in Figure 1. Batches A1 and A2, at lower the ratios (1:0.5 and 1:1), released 35.45 and 30.70% of the drug in the first hour, and the remaining drug was
released within 6 h. This result occurred probably because insufficient polymer was in the formulation. In batch A4 , where the drug-mucilage ratio was 1:2, 23.25% of the drug was released in the first hour, and the remaining drug was released
during 8 h. The rate of release was faster in batch A1 and slower in batch A4. This result showed that as the proportion of mucilage increased, the overall time of release of the drug from the matrix
tablet increased. Drug release from swellable and erodible hydrophilic matrices can be attributed to polymer dissolution,
drug diffusion through gel layer, or a combination of both.
FIGURE1: C.K.Pithawala Institute of Pharmaceutical Science and Research
From this preliminary study, the mucilage extracted from Aloe barbadensis
Miller appears suitable for use as a pharmaceutical excipient in the formulation and manufacture of sustained-release matrix tablets
because of its good swelling, good flow, and suitability for direct-compression formulations. From the dissolution study,
it was concluded that the dried mucilage can be used as an excipient for sustained-release, modified-release, and fast-release
tablets with suitable modifications.
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3. S.A. Bravo, M.C. Lamas, and C.J. Salomon, "Swellable Matrices for the Controlled Release of Diclofenac Sodium: Formulation
and In-vitro Studies," Pharm. Dev. Technol. 9 (1), 75–83 (2004).