The potential implications of these findings when applied to a non-ambient processing method such as Hot Melt Extrusion (HME) are also discussed.

Downstream processing aspects of a stable form of amorphous itraconazole exhibiting enhanced dissolution properties were studied. Preparation of this ternary amorphous solid dispersion by either spray drying or hot melt extrusion led to significantly different powder processing properties. Particle size and morphology was analysed using scanning electron microscopy. Flow, compression, blending and dissolution were studied using rheometry, compaction simulation and a dissolution kit. The spray dried material exhibited poorer flow and reduced sensitivity to aeration relative to the milled extrudate. Good agreement was observed between differing forms of flow measurement, such as Flow Function, Relative flow function, Flow rate index, Aeration rate, the Hausner ratio and the Carr index. The stability index indicated that both powders were stable with respect to agglomeration, de-agglomeration and attrition. Tablet ability and compressibility studies showed that spray dried material could be compressed into stronger compacts than extruded material. Blending of the powders with low moisture, freely-flowing excipients was shown to influence both flow and compression. Porosity studies revealed that blending could influence the mechanism of densification in extrudate and blended extrudate formulations. Following blending, the powders were compressed into four 500 mg tablets, each containing a 100 mg dose of amorphous itraconazole. Dissolution studies revealed that the spray dried material released drug faster and more completely and that blending excipients could further influence the dissolution rate.

A range of 17 ternary formulations of itraconazole (ITZ), HPMCP and Soluplus have been manufactured using spray drying. These amorphous solid dispersions (ASDs) were very stable against crystallisation and ITZ was found to be amorphous in all formulations after one year at 40°C/75% RH. A number of solid state analytical techniques including PXRD, DSC, small angle X-ray scattering, FTIR and solid state NMR were used to characterise the physicochemical properties of the ASDs following processing and storage and to assess any interactions between components. Microtrac laser scattering analysis revealed a relationship between polymer levels and particle size distribution (PSD). Dissolution studies indicated that higher Soluplus content in the formulation resulted in higher concentrations of ITZ in acidic media.

The aim of this study was to evaluate a novel combination of hydroxypropyl methylcellulose phthalate (HPMCP-HP-50) and Soluplus polymers for enhanced physicochemical stability and solubility of the produced amorphous solid dispersions (ASDs). This was achieved using hot melt extrusion (HME) to convert the crystalline active pharmaceutical ingredient (API) into a more soluble amorphous form within the ternary systems. Itraconazole (ITZ), a Biopharmaceutics Classification System class II (BCS II) API, was selected as the model drug. The ASDs were characterized by Powder X-Ray diffraction (PXRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FTIR) spectroscopy, Solid State Nuclear Magnetic Resonance (ssNMR) and dissolution studies. The data showed that the ASDs were physically and chemically stable at 20°C and 50% RH over 12 months. PXRD results indicated that the ITZ in the ASDs was in the amorphous state and no recrystallization occurred. DSC scans confirmed that each formulation exhibited a single intermediate glass transition (T), around 96.4°C, indicating that ITZ was completely miscible in the polymeric blends of HPMCP and Soluplus at up to 30% (w/w) drug loading and that the two polymers were miscible with each other in the presence of ITZ. The FTIR analysis indicated the formation of strong hydrogen bonding between ITZ, HPMCP and Soluplus. The dissolution end-point of the ASDs was determined to be approximately 10 times greater than that of the crystalline ITZ.

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