Calculation of Disintecrant Critical Concentration in Order to Optimize Tablets Disintegration

Abstract

Many reports are available about tablet disintegration mechanisms and several theories are reported in the literature.

All of them are supported by an universally recognized fact which is the necessity of fast water penetration inside the whole tablet. This fact points out the necessity of a continuous hydro-philic network setting up in the tablet structure.

Thereby, the authors after checking the regular adhesion of most of the disintegrant particles on the surface of drug particles, have applied the coordinence equation of Ben Aim and Le Goff, in order to calculate the best disintegrant proportion in a tablet formulation. This calculation will be relevant if the disintegrant particles are more or less spherical (e.g. starch and its derivatives: polyplasdone® XL, Kollidon® CL…). However, the coordinence equation leads to a number of small spherical particles needed for statistical coating of an isolated larger one. Therefore, this quantity will correspond to a double network of the small disintegrant particles between the larger drug particles. In practice, half the quantity of disintegrant particles are enough for a total cover. According to these facts, the equation to determine disintegrant percentage is: d₁ and D₁, real density and mean diameter of disintegrant particles, d₂ and D₂, real density and mean diameter of drug particles.

The same equation can be applied to the diluent percentage calculation.

If disintegrant particles swell in contact with water (e.g. Explotab®, Prirnojel® …) a correction factor will be used: (D_1g = diameter of swollen disintegrant particles).

Many applications have been carried out according to this formulation process and several results are reported.