The influence of formulation variables on the properties of pellets containing a self-emulsifying mixture

A method of converting self-emulsifying drug delivery systems to a pellet f orm has been studied. Formulations with varied relative quantities of an oi l/surfactant mixture, water, microcrystalline cellulose (MCC), and lactose were chosen in a statistical design after preliminary ranging experiments. Pellets were produced by extrusion/spheronization. The characteristics of t he pellets were studied by sieving, disintegration testing, diametral compr ession, image analysis, noncontact laser profilometry, and scanning electro n microscopy. The effects of the formulation variables on pellet properties were evaluated by analysis of variance. It was possible to relate the form ulation variables to all the quantified pellet properties except the shape. The relative quantities of oil/surfactant and water had an effect on the a mount of liquid and oil/surfactant that could be incorporated into the powd er, extrusion force, median diameter, size spread, disintegration time, ten sile strength, and surface roughness. The relative quantities of lactose an d MCC had an effect on the amount of liquid and oil/surfactant that could b e incorporated into the powder, tensile strength, and roughness only. Water was an essential element of the formulations. The maximum quantity of the specific oil/surfactant combination studied that can be incorporated was 42 % of the dry pellet weight. (C) 2001 Wiley-Liss, Inc. and the American Phar maceutical Association.