Jorma Roine

Solid state transformations in consequence of electrospraying – A novel polymorphic form of piroxicam

The aim of the research was to verify that electrospraying of piroxicam yielded a new polymorphic form of this drug. In the experiments, piroxicam was dissolved in chloroform and the solution was atomised electrostatically. Subsequently, the charged droplets were neutralised and dried. The solid drug particles were collected and analysed by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, high performance liquid chromatography, and infrared and Raman spectroscopy. The X-ray diffractogram measured for the electrosprayed piroxicam particles did not match with any of the known piroxicam crystal structures (Cambridge Crystallographic Data Centre). The variable temperature X-ray diffraction showed that the structure recrystallised completely into piroxicam polymorphic formI during heating. No degradation products or solvate removal was detected by high performance liquid chromatography and thermal analysis. The infrared and Raman spectra of the electrosprayed piroxicam were compared to those of formI, and some notable differences in the peak positions, shapes and intensities were detected. The results indicate that electrospraying leads to piroxicam crystallisation in a currently unknown polymorphic form.

Controlled Dissolution of Griseofulvin Solid Dispersions from Electrosprayed Enteric Polymer Micromatrix Particles: Physicochemical Characterization and in Vitro Evaluation.

The oral bioavailability of a poorly water-soluble drug is often inadequate for the desired therapeutic effect. The bioavailability can be improved by enhancing the physicochemical properties of the drug (e.g., dissolution rate, permeation across the gastrointestinal tract). Other approach include shielding the drug from the gastric metabolism and targeted drug release to obtain optimal drug absorption. In this study, a poorly water-soluble model drug, griseofulvin, was encapsulated as disordered solid dispersions into Eudragit L 100-55 enteric polymer micromatrix particles, which were produced by electrospraying. Similar micromatrix particles were also produced with griseofulvin-loaded thermally oxidized mesoporous silicon (TOPSi) nanoparticles dispersed to the polymer micromatrices. The in vitro drug dissolution at pH 1.2 and 6.8, and permeation at pH 7.4 across Caco-2/HT29 cell monolayers from the micromatrix particles, were investigated. The micromatrix particles were found to be gastro-resistant, while at pH 6.8 the griseofulvin was released very rapidly in a fast-dissolving form. Compared to free griseofulvin, the permeability of encapsulated griseofulvin across the intestinal cell monolayers was greatly improved, particularly for the TOPSi-doped micromatrix particles. The griseofulvin solid dispersions were stable during storage for 6 months at accelerated conditions. Overall, the method developed here could prove to be a useful oral drug delivery solution for improving the bioavailability of poorly water-soluble or otherwise problematic drugs.

Processing of pharmaceutical materials by electrospraying under reduced pressure

Abstract Context: Electrospraying was used in drug particle production. Objective: The aim of the research was to evaluate the possibilities to produce drug particles with desired pharmaceutical properties by electrospraying. In particular, the effect of drying pressure on particle properties was studied. Materials and methods: A poorly water soluble model drug (budesonide) was dissolved in chloroform, and the solution was atomized by electrospraying. Following this, the charged droplets were neutralized and dried in a drying chamber. The pressure in the drying chamber was varied. The dried particles were collected and analyzed. Results: The pressure reduction had a slight impact on particle size distribution. The particles produced in reduced pressure turned out to be notably more porous than the particles produced in atmospheric pressure. The pressure reduction also affects the degree of crystallinity of the product. The dissolution of the particles produced in reduced pressures was faster to a certain extent than that of the particles produced in atmospheric pressure. Discussion and conclusions: A setup for electrospraying materials in a reduced pressure was presented. The pressure reduction had a notable impact on particle morphology. The possibilities to tailor the particle properties during electrospraying were studied.

Synthesis and characterization of polypyrrole/H-Beta zeolite nanocomposites

Different amounts of polypyrrole (PPy) were synthesized in aqueous solution on zeolite frameworks by chemical oxidation using FeCl3 as the oxidizing agent at ambient temperature (22 ± 1 °C). The proton form of BEA zeolites with SiO2/Al2O3 ratios of 25, 150 and 300 were used as the host for PPy in this study. Both the anionic groups in the zeolite structures and the chloride ions from the oxidant functioned as the dopants during the polymerization. For comparison, parallel experiments were carried out with only purified pyrrole and FeCl3 in water solution in order to obtain the bulk PPy powder. The nitrogen adsorption–desorption technique, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) were used to characterize the composites. PPy was formed both in the inner and outer surface of the zeolite structures. The composites showed electrical conductivity at ambient temperature in the range from 6.2 × 10−6 to 1.3 S cm−1 depending on the ratio between pyrrole and H-Beta zeolite. Electrochemical behavior of the synthesized samples was investigated by cyclic voltammetry.

Specific Electrocatalytic Oxidation of Cellulose at Carbon Electrodes Modified by Gold Nanoparticles

The influence of the size and oxidation state of Au nanoparticles (AuNPs) as electrocatalysts for the electro‐oxidation of cellulose was studied. Carbon paper electrodes modified with AuNPs were used as the electrocatalysts for the electro‐oxidation of cellulose dissolved in 1.3 m NaOH. The size and oxidation state of the AuNPs were determined by using SEM, TEM, and X‐ray photoelectron spectroscopy. Both the size and the oxidation state of the AuNPs were found to influence the electrocatalytic properties of the electrode, as studied by using cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The carbon paper electrodes decorated with AuNPs (less than 25 nm) that consist of metallic Au gave rise to a significantly higher electrocatalytic activity than a bare polycrystalline Au electrode.