Predicting final product properties of melt extruded solid dispersions from process parameters using Raman spectrometry.

Raman spectrometry was utilized to estimate degraded drug percentage, residual drug crystallinity and glass-transition temperature in the case of melt-extruded pharmaceutical products. Tight correlation was shown between the results obtained by confocal Raman mapping and transmission Raman spectrometry, a PAT-compatible potential in-line analytical tool. Immediate-release spironolactone-Eudragit E solid dispersions were the model system, owing to the achievable amorphization and the heat-sensitivity of the drug compound. The deep investigation of the relationship between process parameters, residual drug crystallinity and degradation was performed using statistical tools and a factorial experimental design defining 54 different circumstances for the preparation of solid dispersions. From the examined factors, drug content (10, 20 and 30%), temperature (110, 130 and 150°C) and residence time (2.75, 11.00 and 24.75min) were found to have significant and considerable effect. By forming physically stable homogeneous dispersions, the originally very slow dissolution of the lipophilic and poorly water-soluble spironolactone was reasonably improved, making 3minute release possible in acidic medium.

Plasticized drug-loaded melt electrospun polymer mats: characterization, thermal degradation, and release kinetics.

Melt electrospinning (MES) was used to prepare fast dissolving fibrous drug delivery systems in the presence of plasticizers. This new method was found promising in the field of pharmaceutical formulation because it combines the advantages of melt extrusion and solvent-based electrospinning. Lowering of the process temperature was performed using plasticizers in order to avoid undesired thermal degradation. Carvedilol (CAR), a poorly water-soluble and thermal-sensitive model drug, was introduced into an amorphous methacrylate terpolymer matrix, Eudragit® E, suitable for fiber formation. Three plasticizers (triacetin, Tween® 80, and polyethylene glycol 1500) were tested, all of which lowered the process temperature effectively. Scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and Raman microspectrometry investigations showed that crystalline CAR turned into an amorphous form during processing and preserved it for longer time. In vitro dissolution studies revealed ultrafast drug dissolution of the fibrous samples. According to the HPLC impurity tests, the reduced stability of CAR under conditions applied without plasticizer could be avoided using plasticizers, whereas storage tests also indicated the importance of optimizing the process parameters during MES.

Polymer-free and polyvinylpirrolidone-based electrospun solid dosage forms for drug dissolution enhancement.

Fast-release nano- and microfibres of lipophilic spironolactone were prepared in a continuous manner by electrostatic spinning, in which the application of polyvinylpyrrolidone K90 as matrix polymer enabled formation of solid solutions. However, instead of the anticipated immediate drug release, temporary precipitation was observed. The polyvinylpyrrolidone web gelled immediately after wetting, hindering drug diffusion and aiding the crystallisation of the solvated amorphous spironolactone. These local supersaturations could be successfully avoided by using hydroxypropyl-ß-cyclodextrin. The dependence of fibre diameter and dissolution rate on the complexing agent-polymer ratio was also studied. A small addition of hydroxypropyl-ß-cyclodextrin proved enough for a dramatic release rate enhancement even in the case of high drug loaded formulations. Transmission Raman spectroscopy, differential scanning calorimetry and X-ray powder diffraction showed that the drug was totally amorphised during processing in all formulations. Polymer-free hydroxypropyl-ß-cyclodextrin fibres containing spironolactone were also electrospun from an ethanolic solution, which is a new way of dissolution improvement in the case of poorly water-soluble drugs. This novel approach ensured nearly total drug release in a minute, making the system a suitable age-appropriate orally dissolving formulation.

Solvent-free melt electrospinning for preparation of fast dissolving drug delivery system and comparison with solvent-based electrospun and melt extruded systems.

The solvent-free melt electrospinning (MES) method was developed to prepare a drug delivery system with fast release of carvedilol (CAR), a drug with poor water solubility. To the authors knowledge, this is the first report for preparing drug-loaded melt electrospun fibers. Cationic methacrylate copolymer of Eudragit® E type was used as a fiber forming polymer matrix. For comparison, ethanol-based electrospinning and melt extrusion (EX) methods were used to produce samples that had the same composition as the melt electrospun system. According to the results of scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and Fourier transformed infrared spectrometry investigations, amorphous solid nanodispersions/solutions of CAR in Eudragit® E matrix were obtained in all cases with 20 m/m % drug content. In vitro drug release in acidic media from the extrudates was significantly faster (5 min) than that from crystalline CAR. Moreover, ultrafast drug release was achieved from the solvent-free melt and ethanol-based electrospun samples because of their huge surface area and the soluble polymer matrix in the acidic media. These results demonstrate that solvent-free MES is a promising, novel technique for the production of drug delivery systems with enhanced dissolution because it can combine the advantages of EX (e.g., solvent-free, continuous process, and effective amorphization) and solvent-based electrospinning (huge product surface area).