Effect of surfactants on the mechanical properties of acetaminophen - wax matrix tablets and its implication on dissolution profile

Abstract

The purpose of this study was to investigate the effect of non ionic surfactant on the mechanical  properties of acetaminophen-wax matrix tablet and hence its implication on dissolution profile.  Acetaminophen-wax matrix granules were prepared by melt granulation technique. This was formed by  triturating acetaminophen powder (100g) with melted carnauba wax (20g), and with varying  concentrations of polysorbate 80 or sorbitan monooleate (0-10%w/w) The molten mass was screened  through sieves and air dried, hence drug to wax ratio was 5:1. The matrix tablets were formed by compressing the wax matrix granules at a constant load (30 arbitrary units on the load scale). The tablets were evaluated for tablet tensile strength, packing fraction, friability and in vitro dissolution profile. The dissolution data were analysed with different mathematical models namely zero order flux, first order, Higuchi, and Korsmeyer and Peppas equations in order to confirm the mechanism of drug release. All the tablets irrespective of concentration or type of surfactant used were compressible with tensile  strength and packing fraction values between 1.47 to 1.63NMm^-2 and 0.96 and 0.98 respectively. Their friability values were = 0.34%. The release rate increased with increase in concentrations of the non-ionic surfactants attributable to enhanced wetting of the solid dosage form by the presence of the surfactant. The analysed dissolution data revealed that the drug release fit first order flux and Higuchi square root of time model evident by their high correlation coefficient (r =0.93). The indication is that the drug release from these matrix tablets is by diffusion-controlled process. The mechanism of drug release was by anomalous (non-Fickian) diffusion indicated by their n values between 0.45 and 0.89. The study  has shown that presence of non- ionic surfactants at an optimised concentration can be used to modulate the release of drug from wax matrix tablets.

Keywords: Wax Matrix Tablets, Non-ionic Surfactants, Tensile Strength, Dissolution Profile, First Order  Flux and Higuchi Square Root of Time Model.