Sustained Release Multiparticulates via Powder Coating

Hydrophobic grade fumed silicas are generally used in tabletting as lubricants. they are also found to retard the release of pharmaceutical actives. this is because of their hydrophobic nature, which gives good cohesive and adhesive properties. considering this point it was thought that they could be used as dry coating agents for solid dosages forms. the model drug selected for this work was paracetamol in granular form and the various coating materials evaluated were hydrophobic grade fumed silicas such as wacker hdk h-20, wacker hdk h-15 and aerosil r-972. aerosil r-972 was found to be satisfactory and extended the release process up to 8 h at concentrations as low as 0.75%. key parameters such as coating, mixing duration, rotation speed in dissolution test, and medium composition were studied, which were shown not to alter the release significantly.