17 research outputs found
Amorphous formulations of indomethacin and griseofulvin prepared by electrospinning
Following an array of optimization
experiments, two series of electrospun
polyvinylpyrrolidone (PVP) fibers were prepared. One set of fibers
contained various loadings of indomethacin, known to form stable glasses,
and the other griseofulvin (a poor glass former). Drug loadings of
up to 33% w/w were achieved. Electron microscopy data showed the fibers
largely to comprise smooth and uniform cylinders, with evidence for
solvent droplets in some samples. In all cases, the drug was found
to exist in the amorphous physical state in the fibers on the basis
of X-ray diffraction and differential scanning calorimetry (DSC) measurements.
Modulated temperature DSC showed that the relationship between a formulation’s
glass transition temperature (<i>T</i><sub>g</sub>) and
the drug loading follows the Gordon–Taylor equation, but not
the Fox equation. The results of Gordon–Taylor analysis indicated
that the drug/polymer interactions were stronger with indomethacin.
The interactions between drug and polymer were explored in more detail
using molecular modeling simulations and again found to be stronger
with indomethacin; the presence of significant intermolecular forces
was further confirmed using IR spectroscopy. The amorphous form of
both drugs was found to be stable after storage of the fibers for
8 months in a desiccator (relative humidity <25%). Finally, the
functional performance of the fibers was studied; in all cases, the
drug-loaded fibers released their drug cargo very rapidly, offering
accelerated dissolution over the pure drug
Ethyl cellulose, cellulose acetate and carboxymethyl cellulose microstructures prepared using electrohydrodynamics and green solvents
Cellulose derivatives are an attractive sustainable material used frequently in biomaterials, however their solubility in safe, green solvents is not widely exploited. In this work three cellulose derivatives; ethyl cellulose, cellulose acetate and carboxymethyl cellulose were subjected to electrohydrodynamic processing. All were processed with safe, environmentally friendly solvents; ethanol, acetone and water. Ethyl cellulose was electrospun and an interesting transitional region was identified. The morphological changes from particles with tails to thick fibres were charted from 17 to 25 wt% solutions. The concentration and solvent composition of cellulose acetate (CA) solutions were then changed; increasing the concentration also increased fibre size. At 10 wt% CA, with acetone only, fibres with heavy beading were produced. In an attempt to incorporate water in the binary solvent system to reduce the acetone content, 80:20 acetone/water solvent system was used. It was noted that for the same concentration of CA (10 wt%), the beading was reduced. Finally, carboxymethyl cellulose was electrospun with poly(ethylene oxide), with the molecular weight and polymer compositions changed and the morphology observed