Tablets are a solid, single dose oral pharmaceutical dosage form and are the most widely used dosage form for medication, as they offer, among other benefits, ease of use. The purpose of this thesis was to determine how tablet composition, shape and tensile strength influence the friability of tablets made with direct compression. The friability is a characteristic that provides a measure of how resistant a tablet is to mechanical stress during the production, storage, distribution, and handling in use. Friability should not be too high, as this predicts damage to the tablet before it reaches the end user.
The tablets were produced with a single punch tablet press. In a preliminary study, we researched the appropriate composition of three different shapes of tablets with the same mass. The type of filler, the proportion and type of glidants were varied and the proportion and type of binder were ideally kept constant. Fillers with different mechanical properties were selected: plastically deformable microcrystalline cellulose, plastic and brittle lactose monohydrate and plastic-elastic pregelatinized starch. The filler type was chosen so that the particle size was approximately 100 μm in all cases. During tableting, we wanted to achieve three equal values of tensile strength in all mixtures, with the lowest being 1 MPa, which allows the film coating process to be carried out in practise. In the main part of the study, batches of tablets were prepared according to the formulations of the three fillers, derived in the preliminary study in a way to be suitable for structured variation of the selected factors. According to the results of the preliminary study, during the compression utilizing three different shapes of punches, the position of the upper punch was adjusted to achieve selected tensile strength values. With the lower punch, the mass of the tablets was adjusted to 300 mg +/- 3 mg.
The flat-round shaped tablets proved to be the most friable, which can be explained by the sharp rectangular edges, which are less pronounced in caplets and round biconvex shaped tablets. The filler that performed the worst in the study was lactose. Tablets made from lactose were most friable regardless of the shape. The reason for their friability is the basic mechanism of deformation – fragmentation. The least friable tablets showed to be microcrystalline cellulose tablets, which can be explained with another mechanism of deformation, which is plastic deformation. Use of higher compression forces results in higher tensile strength and lower friability of tablets. We can note that a higher rotational speed of the abrasion tester drum increases the angle under which tablets fall within the drum. From the results of the study, we cannot establish a correlation between the speeds of the apparatus drum and the friability of tablets.
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