The effect of poloxamer viscosity on liquid-filling of solid dispersions in hard gelatin capsules

Preliminary studies were undertaken on poloxamers to investigate their suitability for liquid-fill formulations for hard gelatin capsules. Poloxamers with viscosity in the range (0.32 - 2.8 Pa s) and melting point 48-58 degrees C were used as the continuous phase, with alpha-lactose monohydrate of negligible solubility in the molten poloxamers, as a model insoluble disperse phase. Physicochemical characterization by rheology, melt solidification and moisture uptake indicated that poloxamers were suitable excipients for liquid-filling in hard gelatin capsules. 10% w/w lactose/poloxamer dispersions were thixotropic and shear thinning and exhibited good capsule-filling properties, disperse-phase uniformity and satisfactory apparent viscosity at 70 degrees C.