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The search for excipients to replace microcrystalline cellulose (MCC) in the production of pellets by extrusion-spheronization in cases of drug incompatibility or the lack of pellet matrix disintegration forms the basis of this study. A combination of к-carrageenan as a spheronization aid, chitosan as a diluent and Carbopol(®) 974P as a binder in the production of pellets containing no MCC has been investigated using acetaminophen as a model drug. Design of experiments allowed assessment of formulation and processing effects on pellet responses that included size, shape, fines, yield and friability. Statistical analysis revealed that the main factors and some of the two-factor interactions had a significant effect on pellet characteristics. Formulations containing high levels of к-carrageenan required more water to produce a wetted mass with good extrudability and extrudate capable of being spheronized. Although only a low level of Carbopol was used in the formulation, it imparted cohesiveness to the wetted mass as well as the extrudate. Furthermore, it was discovered that Carbopol could act as an extrusion aid, enabling the wetted mass to flow easily through the extruder screen holes without building up heat. Spherical and rugged pellets were produced that met the immediate release criterion.