Blends of poly(ethylene oxide)/poly(methyl methacrylate). An i.r. and n.m.r. study

Solid-state nuclear magnetic resonance study of the physical stability of electrospun drug and polymer solid solutions

A major challenge in utilizing the amorphous form of an active pharmaceutical ingredient (API) in a final oral dosage form is preventing crystallization over time and ensuring stability. One method to improve stability is lowering the mobility of an API by formulating as a solid solution with an excipient. In this work, we use electrospinning to prepare solid solutions of API, aliskiren (SPP) or indomethacin (IND), and a polymer, polyvinylpyrrolidone (PVP). The stability of the solid solutions over 6-month storage in a desiccator at 40 °C was investigated. Using X-ray diffraction and differential scanning calorimetry, it was determined that no crystals were present in the four formulations tested--1:1 SPP-PVP, 4:1 SPP-PVP, 1:1 IND-PVP, and 2:1 IND-PVP at any time. Solid-state nuclear magnetic resonance relaxation time measurements were used to determine whether phase separation of the API and polymer occurred during the study period. It was found that all formulations remained homogeneous down to at least a 2-10 nm length scale, indicating that for these APIs, electrospinning is an acceptable method for forming stable amorphous solid solutions.

Analysis of semibatch emulsion polymerization: role of ultrasound and initiator

In this work semibatch miniemulsion was carried out wherein the effect of free radicals produced by ultrasound and an external addition of initiator was examined. Influence of different variables on polymerization rate and polymer particle size has also been investigated. Over a range of 0-4% (by wt) initiator, the polymerization rate was found to increase over a range of 0.56-1.33 g L(-1) min(-1). Similarly monomer concentration range (7.2-15 wt.%) changed the polymerization rate from 1.33 to 2.61 g L(-1) min(-1). Under optimum parametric conditions polymer particle size 50 nm were obtained with a narrow size distribution. Syndiotactic phase of PMMA was observed by controlling the formulation recipe. Although, number of reports could be found in the literature [9,13,17,18,20,22] related to batch emulsion polymerization, this experimental data could be useful for the production of large scale monodispersed PMMA latex as all of the scale-up and design parameters have been qualitatively addressed.

Solid-state NMR characterization of high-loading solid solutions of API and excipients formed by electrospinning

A major focus area in improving pharmaceutical manufacturing is decreasing powder-handling steps such as milling, granulation, and blending. One approach to go directly from active pharmaceutical ingredients (API) and excipients in solution to a formulated drug product is to use electrospinning to make solid formulations of API in a polymer. Because of the rapid evaporation rate in electrospinning, the process usually results in a well-mixed solid dispersion of drugs in the polymer. In this study, solid-state nuclear magnetic resonance is used to examine phase separation in formulations of aliskiren (SPP) and indomethacin (IND) with polyvinylpyrrolidone (PVP) prepared by electrospinning and hot-melt extrusion. It was found that 1:1 SPP-PVP, 1:1 IND-PVP, and 4:1 SPP-PVP formulations prepared by electrospinning are homogeneous solid solutions down to a 2-11 nm length scale, whereas a 4:1 SPP-PVP formulation prepared by hot-melt extrusion exhibits phase separation with domain sizes of 20-100 nm or larger.