Biomedical subjects

Hoo-Kyun Choi

Publications and source records attributed to Hoo-Kyun Choi.

24 records · Page 2Linked to original sources

PubMed2002

Release of triamcinolone acetonide from mucoadhesive polymer composed of chitosan and poly(acrylic acid) in vitro.

Transmucosal drug delivery (TMD) system using mucoadhesive polymer has been recently interested due to the rapid onset of action, high blood level, avoidance of the first-pass effect and the exposure of the drug to the gastrointestinal tract. A novel mucoadhesive polymer complex composed of chitosan and poly(acrylic acid) (PAA) was prepared by template polymerization of acrylic acid in the presence of chitosan for the TMD system. Triamcinolone acetonide (TAA) was loaded into the chitosan/PAA polymer complex film. TAA was evenly dispersed in chitosan, PAA polymer complex film without interaction with polymer complex. Release behavior of TAA from the mucoadhesive polymer film was dependent on time, pH, loading content of drug, and chitosan PAA ratio. The analysis of the drug release from the mucoadhesive film showed that TAA might be released from the chitosan/PAA polymer complex film through non-Fickian diffusion mechanism.

Acrylic Resins↗

PubMed2002

Pharmacokinetic and pharmacodynamic evaluation of cyclosporin A O/W-emulsion and microsphere formulations in rabbits.

O/W-emulsion and microspheres containing cyclosporin A (CSA) were prepared to investigate the feasibility of developing new formulations. The pharmacokinetic and pharmacodynamic characteristics of these preparations were evaluated in rabbits and compared to two commercial products, Sandimmun Neoral for oral administration and CIPOL Inj. for intravenous administration. After oral or intravenous administration (10 mg/kg) to male rabbits, CSA concentration and lymphocyte population in whole blood were measured by TDxFLx and Coulter STKS, respectively. Total clearance (CL(t)) was increased after intravenous administration of CSA O/W-emulsion compared with intravenous administration of CIPOL Inj. In case of oral administration, AUC and bioavailability of CSA microspheres and O/W-emulsion were not significantly different (P>0.05) from those of Sandimmun Neoral, however, MRT and T(max) of CSA microspheres and O/W-emulsion were significantly increased (P<0.05). There were no significant differences in the area between the baseline and effect curves (ABEC) among these formulations (P>0.05), but the pharmacodynamic availability (F(PD)) of CSA O/W-emulsion was 5.51-fold higher than that of CIPOL Inj. and was significantly greater than that of Sandimmun Neoral (P<0.05). These results suggest that CSA microspheres and O/W-emulsion have sustained release characteristics and may be used as such formulations for oral or intravenous administration of CSA.

Animals↗

PubMed2002

Enhanced percutaneous absoption of piroxicam via salt formation with ethanolamines.

PURPOSE: The aim of this work was to prepare piroxicam-ethanolamine salts (PX-EAs) with improved physicochemical properties for transdermal application. METHODS: The physicochemical properties of prepared salts were investigated by DSC and FT-IR. Their percutaneous absorption characteristics across hairless mouse skin and the effect of various enhancers were studied using a flow-through diffusion cell system. RESULTS: Three piroxicam-ethanolamine salts were prepared. Piroxicam monoethanolamine salt (PX-MEA) and piroxicam diethanolamine salt (PX-DEA) had higher solubility than piroxicam in most of vehicles tested and a higher permeation rate across the skin. The solubility and permeation rate of piroxicam triethanolamine salt (PX-TEA) was lower than those of piroxicam in most of vehicles tested. However, there was no significant change in octanol/water partition coefficient by salt formation. Salt formation lowered the melting point of piroxicam and, of the systems examined, PX-DEA showed the lowest melting point. When the effect of various enhancers were evaluated, nonionic surfactants having medium HLB, an alkyl chain length of C18 and an ethylene oxide chain were better able to modify the permeability of the stratum corneum and to promote the effective penetration of piroxicam and PX-EAs. CONCLUSIONS: Piroxicam salt formation with MEA and DEA improved the physicochemical properties and enhanced the skin permeability of piroxicam.

Administration, Cutaneous↗

PubMed2002

Transdermal delivery of physostigmine: effects of enhancers and pressure-sensitive adhesives.

The purpose of this study was to investigate the effects of various pressure-sensitive adhesives (PSA) on the percutaneous absorption of physostigmine across hairless mouse skin. In addition, the influences of various vehicles and polyvinylpyrrolidone (PVP) on the percutaneous absorption of physostigmine from PSA matrix across hairless mouse skin were evaluated using a flow-through diffusion cell system at 37 degrees C. Physostigmine showed the highest permeability from silicone adhesive matrix, followed by polyisobutylene (PIB), styrene-isoprene-styrene (SIS), acrylic, and styrene-butadiene-styrene (SBS) matrix. Among acrylic adhesives, the permeability of physostigmine was the highest from grafted acrylic adhesive. Polyvinyl pyrrolidone inhibited the crystallization of physostigmine in the PIB adhesive matrix and enhanced the permeability of physostigmine from the PIB adhesive matrix. When esters of sorbitol and fatty acid, polyethylene glycol (PEG) alkyl esters, and caprylic/capric triglycerides were tested, the more lipophilic was a surfactant, the higher the permeation rate within the same group of surfactants. The enhancement effect of PEG derivatives was lower than that of non-PEG derivatives. Among non-linear fatty acid derivatives, linoleate derivatives showed higher permeability of physostigmine than oleate derivatives. This study showed that several non-ionic surfactants, including PEG-20 evening primrose glyceride, enhanced the permeation of physostigmine across hairless mouse skin better than oleic acid.

Adhesives↗

PubMedDate not supplied

Effects of vehicles and pressure sensitive adhesives on the penetration of isosorbide dinitrate across the hairless mouse skin.

The effects of various vehicles and adhesives on the percutaneous absorption of isosorbide dinitrate (ISDN) were evaluated. Lauroglycol FCC showed the highest flux among vehicles tested. The flux of ISDN from silicone and acrylic adhesive matrices was found to be higher than that from other types of adhesive matrices. No statistically significant relationship between the flux from acrylic PSA and the flux from a solution formulation was observed. A highly cross-linked acrylic adhesive gave higher permeation rates than the other acrylic adhesives examined. N-decylmethyl sulfoxide showed the highest enhancing effect on the flux of ISDN from acrylic adhesive. The relationship between the HLB values of vehicles and the measured flux showed a decrease of flux at HLB values greater than 12.

Adhesives↗

PubMedDate not supplied

Preparation of various solid-lipid beads for drug delivery of enrofloxacin.

Solid-lipid beads were prepared to retard the release rate of enrofloxacin and to mask its bitter taste using carrageenan or sodium alginate as a shell material and either cacao butter or Witepsol W-35 as a solid lipid core. Sodium alginate was a better shell material than carrageenan and the highest loading efficiency was obtained using 2% sodium alginate. The alginate beads had a spherical morphology and a sturdy shell structure. The enrofloxacin release rate at room temperature was greatly reduced. Solid-lipid beads have the potential to mask the bitter taste of enrofloxacin and extend its release rate.

Drug Delivery Systems↗