Formulation of insoluble drugs. Study of pharmaceutical suspensions by response surface methodology

The preformulation of insoluble drugs, sulfadiazine and aluminium hydroxyde, were studied in order to achieve a suspension with desirable requirements. The objective of the formulator is to avoid the irreversible aggregation called “caking”, and to obtain a suspension with an airy, large volume sediment easily redispersible and with suitable rheological properties. An experimental design useful to determine optimal properties is a Central Composite Design. The surfactant, thickener and electrolyte at different proportions are the 3 factors studied. This strategy allows to point on the main significant effect and to determine the concentrations of each product leading to optimal properties of the suspensions.