Solving the insoluble
Dow Pharma has added to its Affinisol line of drug solubility enhancement products. The product range, which is designed to tackle insolubility in spray dried dispersion (SDD) and hot melt extrusion (HME) formulations now has two new additions – one for each process.
“Following the announcement of the completion of the new operational facility for Dow’s Affinisol HPMCAS (hydroxypropyl methylcellulose acetate succinate) at the Cambrex Karlskoga site last October and the subsequent ability for Dow to commercially supply solubility enabling excipients early 2014, we have further strengthened our offering for HME formulations and are pleased to present two extrusion case studies utilising BCS Class II Active Pharmaceutical Ingredients (APIs) and Affinisol HPMC HME” said Christophe Massip, global marketing director, Dow Pharma & Food Solutions.
Affinisol HPMCAS (Hypromellose Acetate Succinate) is a range of polymers developed in collaboration between Dow Pharma & Food Solutions and Bend Research to help maintain stable solid dispersions and inhibit API crystallisation. Not all active ingredients are able to achieve a balance between peak drug concentration and sustainment of supersaturated drug concentration using conventional HPMCAS grades. The commercially available Affinisol HPMCAS offers more polymer tailoring options for solubilisation performance than peer offerings, according to Dow.
Hypromellose is commonly used as a crystallisation inhibitor in amorphous solid dispersions in both the solid state and during dissolution. Application of hypromellose into hot melt extrusion formulations has been successful but limited, however, due to the narrow temperature range between thermal softening and discoloration as well as a high melt viscosity. Existing hypromellose materials require the use of plasticisers to broaden this processing range, but incorporation of these materials can be detrimental to the final product.
Dow says that its new design of the cellulosic polymer maintains the crystallisation inhibiting properties of traditional HPMC, but can be extruded over a wide temperature range without the use of plasticisers. Because of a low glass transition temperature, HPMC HME reportedly allows the user to formulate amorphous solid dispersions and controlled release profiles via extrusion processes.