• Polymer(Korea)
• /
• v.28 no.4
• /
• pp.291-297
• /
• 2004

Water-soluble chitosan micro spheres were prepared by emulsification of chitosan solution in mineral oil followed by cross linking reaction with different amount of the cross linking agent (glutraraldehyde), different chitosan concentration. Then, the physicochemical properties such as morphological change by degradation, drug loading efficiency, and drug release profiles were investigated with the drug loaded water-soluble chitosan microspheres. Norfloxacin loaded water-soluble chitosan micro spheres showed excellent drug entrapping capacities without burst release caused by surface bound drug. The absence of the surface bound drug also confirmed by X-ray diffraction study. Degradation and drug release studies showed that the amount of the crosslinking agent played a crucial role for drug loading, release and degradation. The water-soluble chitosan micro spheres showed more sustained drug release profiles with slower degradation and larger particle size by increasing crosslinking agent.

• Journal of Pharmaceutical Investigation
• /
• v.34 no.4
• /
• pp.275-281
• /
• 2004

We have studied the effect of polarity, current density, current duration, crosslinking density, swelling ratio, and permeation enhancers on the transdermal flux of ketoprofen from acrylamide hydrogel. Hydrogel was prepared by free radical crosslinking polymerization of acrylamide. Drug loading was made just before transport experiment by soaking the hydrogel in solution containing drug. In vitro flux study using hairless mouse skin was performed at $36.5^{\circ}C$ using side-by-side diffusion cell, and the drug was analysed using HPLC/UV system. The result showed that, compared to passive flux, the total amount of drug transported increased about 18 folds by the application of $0.4\;mA/cm^2$ cathodal current. Anodal delivery with same current density also increased the total amount of drug transported about 13 folds. It seemed that the increase in flux was due to the electrorepulsion and the increase in passive permeability of the skin by the current application. Flux increased as current density, the duration of current application and loading amount (swelling duration) increased. As the cross linking density of the hydrogel increased, flux clearly decreased. The effect of hydrophilic enhancers (urea, N-methyl pyrrolidone, Tween 20) and some hydrophobic enhancers (propylene glycol monolaurate and isopropyl myristate) was minimal. However, about 3 folds increase in flux was observed when 5% oleic acid was used. Overall, these results provide some useful information on the design of an optimized iontophoretic delivery system of ketoprofen.

• Archives of Pharmacal Research
• /
• v.28 no.3
• /
• pp.370-375
• /
• 2005

The objective of this study was to develop a new reverse micelle-based microencapsulation technique to load tetracycline hydrochloride into PLGA microspheres. To do so, a reverse micellar system was formulated to dissolve tetracycline hydrochloride and water in ethyl formate with the aid of cetyltrimethylammonium bromide. The resultant micellar solution was used to dissolve 0.3 to 0.75 g of PLGA, and microspheres were prepared following a modified solvent quenching technique. As a control experiment, the drug was encapsulated into PLGA microspheres via a conventional methylene chloride-based emulsion procedure. The micro­spheres were then characterized with regard to drug loading efficiency, their size distribution and morphology. The reverse micellar procedure led to the formation of free-flowing, spherical microspheres with the size mode of 88 ~m. When PLGA microspheres were prepared follow­ing the conventional methylene chloride-based procedure, most of tetracycline hydrochloride leached to the aqueous external phase: A maximal loading efficiency observed our experimental conditions was below $5\%$. Their surfaces had numerous pores, while their internal architecture was honey-combed. In sharp contrast, the new reverse micellar encapsulation technique permitted the attainment of a maximal loading efficiency of 63.19 $\pm$$0.64\%$. Also, the microspheres had smooth and pore-free surfaces, and hollow cavities were absent from their internal matrices. The results of this study demonstrated that PLGA microspheres could be successfully prepared following the new reverse micellar encapsulation technique.

• YAKHAK HOEJI
• /
• v.31 no.1
• /
• pp.25-32
• /
• 1987

The effect of loading dose, plasticiser and PVA molecular weight on naproxen release from hydrophilic polymer matrix was examined. Hydrophilic polymer matrix was prepared with PVA and PVP by adding glycerine as plasticiser. The release of naproxen from polymer matrix was determined in phosphate buffer medium. The release rate of naproxen from the polymer matrix increased as drug loading dose and plasticiser percentage increased. Raproxen released from the polymer matrix showed the time square root kinetics. Without changing the release-pattern, the release rate of naproxen could not be changed by varying molecular weight of PVA. Linearly released time range increased as drug loading dose increased, whereas decreased as plasticiser percentage increased up to 30%.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.3
• /
• pp.867-872
• /
• 2011

For the prolonged delivery and sustained release rates of low molecular weight drugs, poly(lactic-co-glycolic acid) (PLGA) microparticles containing the drug SKL-2020 have been investigated. On increasing polyvinyl alcohol (PVA) concentration (from 0.2% to 5%), the size of microparticles decreased (from $48.02{\mu}m$ to $10.63{\mu}m$) and more uniform size distribution was noticeable due to the powerful emulsifying ability of PVA. A higher drug loading (from 5% to 20%) caused a larger concentration gradient between 2 phases at the polymer precipitation step; this resulted in decreased encapsulation efficiency (from 34.19% to 25.67%) and a greater initial burst (from 61.71% to 70.05%). SKL-2020-loaded PLGA microparticles prepared with different fabrication conditions exhibited unique release patterns of SKL-2020. High PVA concentration and high drug loading led to an initial burst effect by rapid drug diffusion through the polymer matrix. Since PLGA microparticles enabled the slow release of SKL-2020 over 1 week in vitro and in vivo, more convenient and comfortable treatment could be facilitated with less frequent administration. It is feasible to design a release profile by mixing microparticles that were prepared with different fabrication conditions. By this method, the initial burst could be repressed properly and drug release rate could decrease.

• Journal of Pharmaceutical Investigation
• /
• v.41 no.1
• /
• pp.1-7
• /
• 2011

The effects of different formulation variables including pressure sensitive adhesive (PSA), permeation enhancer, thickness of the matrix and loading amount of drug on the transdermal absorption of galantamine were investigated across the hairless mouse skin. The permeation profile of galantamine was different depending on the types of PSA, loading amount of drug, thickness of the matrix and type of enhancer used. Highest flux of galantamine was obtained from acrylic PSA but crystals were formed in the patch within 72 h. Among the PSAs screened, crystal formation was not observed only in the patches formulated in Styrene Butadiene Styrene (SBS) matrix. Permeation rate increased linearly as the concentration of galantamine in SBS matrix increased from 2.5 to 15% w/w. Among the enhancers screened, Brij$^{(R)}$ 30 provided highest flux of galantamine. Matrix thickness of 80 ${\mu}m$ was optimum for maintaining adhesiveness as well as consistently delivering galantamine for longer period of time.

• Bulletin of the Korean Chemical Society
• /
• v.19 no.9
• /
• pp.962-967
• /
• 1998

Block copolymers consisting of poly(rbenzyl L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) as the hydrophilic part were synthesized and characterized. Polymeric micelles of the block copolymers (abbreviated GEG) were prepared by a dialysis method. The GEG block copolymers were associated in water to form polymeric micelles, and the critical micelle concentration (CMC) values of the block copolymers decreased with increasing PBLG chain length in the block copolymers. Transmission electron microscopy (TEM) observations revealed polymeric micelles of spherical shapes. From dynamic light scattering (DLS) study, sizes of polymeric micelles of GEG-1, GEG-2, and GEG-3 copolymer were 106.5±59.2 nm, 79.4±46.0 nm, and 37.9±13.3 nm, respectively. The drug loading contents of GEG-1, GEG-2 and GEG-3 polymeric micelles were 12.6, 11.9, and 11.0 wt %, respectively. These results indicated that the drugloading contents were dependent on PBLG chain length in the copolymer; the longer the PBLG chain length, the more the drug-loading contents. Release of norfloxacin (NFX) from the nanoparticles was slower in higher loading contents of NFX than in lower loading contents due to the hydrophobic interaction between PBLG core and NFX.

• Journal of Pharmaceutical Investigation
• /
• v.38 no.1
• /
• pp.63-72
• /
• 2008

Meloxicam-loaded microspheres were prepared with poly(D,L-lactic acid)(PLA) by a solvent-emulsion evaporation method. The morphology, particle size, drug loading capacity, drug entrapment efficiency (EE) and release patterns of drug were investigated in vitro. Various batches of micro spheres with different size and drug content were obtained by changing the ratio of meloxicam to $PLA^{\circ}{\AE}s$ with different molecular weight, PLA concentration in the dispersed phase and stirring rate. Meloxicam crystals on microsphere surface, which were released rapidly and could act as a loading dose, were observed with increasing drug content. The release rate was increased with increase in drug contents and decrease in the molecular weight of PLA. Microspheres prepared with smaller molecular weight produced faster drug release rate. The release rate of meloxicam for long-acting injectable delivery system in vitro, which would aid in predicting in vivo release profile, could be controlled by properly optimizing various factors affecting characteristics of microspheres. Blood concentration-time profile of meloxicam after intramuscular injection of meloxicam-loaded microspheres in rabbits showed possibility of long term application of this system in clinical settings.

• KSBB Journal
• /
• v.5 no.4
• /
• pp.377-382
• /
• 1990

The characteristics controlled drug release have been studied for biodegradable polymer matrix. Polymer matrix was prepared from glycerine, prednisolone and dextran. Mathematical analysis of the data showed that the release behavior actually conformed to the Higuchi's diffusion controlled model. The release time was increased as drug loading doses increased, whereas decreased as glycerine concentration increased. The release rate did not change by varying molecular weight of dextran.

• Journal of Forest and Environmental Science
• /
• v.35 no.3
• /
• pp.141-149
• /
• 2019

Nanocellulose, which can exist as either cellulose nanocrystals or cellulose nanofibrils, has been used as a biomaterial for drug delivery owing to its non-immunogenicity, biocompatibility, high specific area, good mechanical properties, and variability for chemical modification. Various water-soluble drugs can be bound to and released from nanocelluloses through electrostatic interactions. The high specific surface area of nanocellulose allows for high specific drug loading. Additionally, a broad spectrum of drugs can bind to nanocellulose after facile chemical modifications of its surface. Controlled release can be achieved for various pharmaceuticals when the nanocellulose surface is chemically modified or physically formulated in an adequate manner. This review summarizes the potential applications of nanocelluloses in drug delivery according to published studies on drug delivery systems.