Alternative extrusion-spheronization aids

Microcrystalline cellulose (MCC) is the most widely used extrusion-spheronization aid but is associated with several limitations such as adsorption of actives, longer dissolution time, and degradation of some sensitive drugs such as ranitidine.

This article reviews a number of natural, semisynthetic, and synthetic agents, such as cross-linked polyvinylpyrrolidone, carrageenan, chitosan, pectinic acid, modified starches, coprocessed MCC, glycerides, chitosan, sodium alginate, and β-cyclodextrin (CD) for their potential as alternative extrusion-spheronization aids to MCC.

Alternative spheronizing aids were characterized and evaluated based on their intrinsic properties such as solubility, water absorption and retention capacity, rheology, surface properties, binding capacity, drug release, and pellets properties such as sphericity, porosity, and friability with respect to MCC.

Crospovidone, carrageenan, chitosan, pectinic acid, glycerides, β-CD, and cellulose derivatives are effective alternative spheronizing aids and can be used to prepare pellets without any plasticizer or lubricant. But pellets with polyethylene oxide can only be produced with the use of plasticizer and/or lubricant. However, none of them succeeded to provide the same flexibility in formulation and processing during extrusion-spheronization as observed for MCC (e.g., less water-holding capacity, narrow liquid range providing the correct rheology for extrusion-spheronization, addition of binder required to obtain sufficient mechanical strength).