The effects of interacting variables on the tensile strength, disintegration and dissolution of paracetamol tablets.

A factorially designed scheme has been used to analyse the separate and combined effects of packing fraction (P), nature of binder (N) and concentration of binder (C) on the tensile strength, disintegration and dissolution (t50%) times of paracetamol tablets. In general, P has the greatest effect on tensile strength, disintegration and dissolution times followed by C then N. For the variables in combination, the ranking of the effects on tensile strength, for the PVP/gelatin formulations, are P x N greater than N x C greater than P x C and for the PVP/tapioca formulations are P x C = N x C greater than P x N. For disintegration and for dissolution, the ranking for the PVP/gelatin formulations are P x C greater than P x N = N x C and P x N greater than P x C greater than N x C, respectively, and for the PVP/tapioca formulations are P x N greater than N x C = P x C. The results also show that tapioca acts as a binding agent when included in paracetamol tablet formulations, but it is a weaker binder than either PVP or gelatin. It is thus required in a higher concentration to produce tablets of comparable physical properties with those formulated with PVP or gelatin.