• Journal of Pharmaceutical Investigation
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• v.24 no.3
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• pp.155-165
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• 1994

Some mucoadhesive polymers such as hydroxypropylcelluose (HPC) and carbopol-934 (CP) have been employed for the preparation of mucoadhesive polymeric systems, and their physical properties including mucoadhesion, swelling, and drug release were evaluated. A new simple experimental technique that can quantitatively measure the bioadhesive properties of various polymeric systems has been developed by the methods of detachment force test. As the polymeric systems, the discs of freeze-dried HPC/CP solid dispersions were prepared. The mucosa used in these tests were upper, middle, and lower parts of small intestine of male rats weighing $300{\sim}350\;g$. Detachment forces were increased as the mole fraction of CP increased in discs of HPC/CP solid dispersions. In the points of intestinal site dependence of mucoadhesion, the solid dispersions revealed non-specific mucoadhesion to the intestine. Swelling and drug release characteristics of mucoadhesive polymeric systems were studied extensively to find out the feasibility for the oral controlled delivery systems. Swelling ratio, expressed as the final height/initial height, has been determined in various pH buffer solutions. Hydrochlorothiazide (HCT) was employed as a model drug for release study. Apparent swelling and drug release rate constants, $K_s$ and $K_r$ respectively, were obtained from the square-root time plot of either swelling ratio or released amount of drug, particularly for the time periods before reaching the equilibrium. As a result, the swelling ratio of HPC/CP solid dispersions was increased as the weight percentage of CP increased. Similarly, the release of HCT from the solid dispersions was dependent on pH changes and CP contents, resulted in the slower release of HCT with the increases of pH and CP contents.

• Journal of the Korean Ceramic Society
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• v.32 no.5
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• pp.594-600
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• 1995

Spherical alumina gel powders were produced by hydrolysis of aluminum sec-butoxide (Al(sec-OC4H9)3) in a n-octanol/acetonitrile mixed solvent. The enlargement of particle size was induced by increasing HPC (hydroypropylcellulose) concentration (0.005, 0.1, and 0.05 g/ι) and emulsion-state aging time (10 min and 360 min). Mean particle sizes of dried alumina gel powders increased from 1.4 ${\mu}{\textrm}{m}$ to 3.5${\mu}{\textrm}{m}$ at 10-min emulsion-state aging time and from 1.9${\mu}{\textrm}{m}$ to 4.1${\mu}{\textrm}{m}$ at 360-min emulsion-state aging time as HPC concentration increased from 0.005 g/ι to 0.05 g/ι. At the same HPC concentration, particle size of dried alumina gel powder increased with increasing of emulsion-state aging time from 10 min to 360 min. The increase in the average particle size of dried alumina gel powder with increase in HPC concentration was interpreted as the enlargement of particles from alkoxide emulsions unprotected by HPC. The produced dried gel powder calcined at 115$0^{\circ}C$ for one hour transformed to $\alpha$-alumina.

• Journal of Pharmaceutical Investigation
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• v.37 no.6
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• pp.355-358
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• 2007

To develop a sustained-release tablet which had the similar dissolution to commercial ibudilast-loaded sustained-release capsule, the tablets were prepared using hydroxypropylmethylcellulose phthalate (HPMCP), ethylcellulose (EC) and hydroxypropylcellulose (HPC), and dissolution test were carried out with paddle method in KP. The tablet prepared only with HPMCP and EC showed sno similar dissolution pattern to the commercial product. As the ratio of HPMCP/HPC in tablet decreased, the dissolution rate of drug decreased in pH 1.2 but increased in pH 6.8. Furthermore, an ibudilast-loaded sustained-release tablet composed of [ibudilast/EC/HPMCP/HPC (10/10/170/10 mg/tab)] gave similar dissolution to commercial product in pH 1.2 for 3 h and in pH 6.8 for 10 h. Thus, it could be a potential candidate for the substitute of commercial capsule.

• Polymer(Korea)
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• v.26 no.4
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• pp.523-534
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• 2002

A new hydroxypropylcellulose (HPC) capable of exhibiting reflection colours in the temperature ranges of about 60-$130^{\circ}C$ and acrylic acid esters of HPC (ESs) with degree of esterification (DE) ranging from 1 to 3 were synthesized. The crosslinked ES films with the optical pitch ($\lambda_m$) ranging throughout the visible region were also prepared by exposing thermotropic cholesteric phases of ESs with a DE of more than 2 to UV light at $50^{\circ}C$. The thermal and optical properties for both the uncrosslinked and crosslinked samples and the swelling behavior of the crosslinked films in acetone were investigated. The $\lambda_m$'s of ESs, as well as HPC itself, increased with temperature. However, the $\lambda_m$'s of ESs were larger than of HPC at the same temperature and decreased with increasing DE. The temperature dependence of $\lambda_m$of the crosslinked samples was much weaker than that of ESs. Moreover, in contrast with ESs that exhibit a decrease of the isotropization temperature with increase in the DE, the networks were found to decompose at about $210^{\circ}C$, giving no transition to an isotropic state. The crosslinked samples exhibited an anisotropic swelling, suggesting that the two-dimensional crosslinking preferentially performs between ES molecules.