Jung-Myung Ha

Preparation of highly porous gastroretentive metformin tablets using a sublimation method.

The present investigation is aimed to formulate floating gastroretentive tablets containing metformin using a sublimation material. In this study, the release of the drug from a matrix tablet was highly dependent on the polymer concentrations. In all formulations, initial rapid drug release was observed, possibly due to the properties of the drug and polymer. The effect of the amount of PEO on swelling and eroding of the tablets was determined. The water-uptake and erosion behavior of the gastroretentive (GR) tablets were highly dependent on the amount of PEO. The water-uptake increased with increasing PEO concentration in the tablet matrix. The weight loss from tablets decreased with increasing amounts of PEO. Camphor was used as the sublimation material to prepare GR tablets that are low-density and easily floatable. Camphor was changed to pores in the tablet during the sublimation process. SEM revealed that the GR tablets have a highly porous morphology. Floating properties of tablets and tablet density were affected by the sublimation of camphor. Prepared floating gastroretentive tablets floated for over 24 h and had no floating lag time. However, as the amount of camphor in the tablet matrix increased, the crushing strength of the tablet decreased after sublimation. Release profiles of the drug from the GR tablets were not affected by tablet density or porosity. In pharmacokinetic studies, the mean plasma concentration of the GR tablets after oral administration was greater than the concentration of glucophase XR. Also, the mean AUC(0-∞) values for the GR tablets were significantly greater than the plasma concentrations of glucophase XR.

Investigation of formulation factors affecting in vitro and in vivo characteristics of a galantamine transdermal system.

Because of low treatment compliance with the Alzheimer disease patients, there have been clinical needs for the alternative administration route to effective and well-tolerated approaches of galantamine (Small and Dubois, 2007). In this study, drug-in-adhesive transdermal patches with galantamine were prepared and evaluated in vitro and in vivo. The in vitro permeation studies indicated that DT-2510 was the most suitable pressure-sensitive-adhesive and oleic acid was the most promising enhancer for galantamine drug-in-adhesive patch. The optimized galantamine drug-in-adhesive patch could be physicochemically stable for 28 days at 40 °C/75% RH. The in vivo studies of the optimized galantamine drug-in-adhesive patch showed high absolute bioavailability of around 80% and sustained effect on the drug plasma levels for 24 h. The in vitro and in vivo studies of galantamine drug-in-adhesive patches with different pressure-sensitive-adhesive functional groups showed a strong correlation between the skin permeation rate and the area under the curve. The results suggest that the transdermal application of galantamine drug-in-adhesive patches might be the alternative dosage form to have good efficacy and tolerability for the treatment of Alzheimer disease.

Formulation of solid dispersion of rebamipide evaluated in a rat model for improved bioavailability and efficacy

Objectives  Rebamipide, a novel anti‐ulcer agent, is listed in biopharmaceutics classification class IV because of its low aqueous solubility and permeability. Consequently, the bioavailability of rebamipide is under 10% in humans. The aim of this study was to increase the solubility and determine the effect of solubility enhancement on the bioavailability and efficacy of rebamipide (RBM).

Preparation and evaluation of dual-mode floating gastroretentive tablets containing itraconazole.

Abstract The aims of the present study were to prepare new dual-mode floating gastroretentive tablets (DF-GRT) containing itraconazole (ITR) and to evaluate influence of the dosage forms on pharmacokinetic parameters of ITR. The solubility of ITR was enhanced around 200 times (from 1.54 to 248.38 µg/mL) by preparing solid dispersion (SD) with hydroxypropylmethyl cellulose. Buoyancy of DF-GRT containing ITR-SD was established by both camphor sublimation and gas generation. Camphor sublimation decreased density of DF-GRT by making pores in tablet matrix, which led to elimination of lag time for floating. Carbon dioxide generated by sodium bicarbonate and citric acid helped to maintain buoyancy of DF-GRT. Therefore DF-GRT floated on the medium without lag time until disintegrated entirely during in vitro release study. They released 89.11% of the drug at 2 h. Residual camphor was <0.5 wt% after sublimation. The pharmacokinetics of DF-GRT was evaluated in six miniature pigs and compared to immediate release tablets (IRT). Mean AUC ratio of GRT/IRT was 1.36 but there was no statistical difference between AUC values. However delayed tmax, increased MRT and equivalent Cmax of DF-GRT supposed it could be a promising tool for gastroretentive drug delivery system containing ITR.

Physicochemical, pharmacokinetic and pharmacodynamic evaluations of novel ternary solid dispersion of rebamipide with poloxamer 407

This study was conducted primarily to improve the solubility of rebamipide, a poorly water-soluble anti-ulcer drug, using novel ternary solid dispersion (SD) systems and secondly to evaluate the effect of solubility enhancement on its pharmacokinetic (PK) and pharmacodynamic (PD) profile. After dissolving the three components in aqueous medium, ternary SD containing the drug, sodium hydroxide (NaOH) and PVP-VA 64 was achieved by spray drying method, which was used as primary SD. Poloxamer 407, a surfactant polymer, was incorporated in this primary SD by four different methods: co-grinding, physical mixing, melting or spray drying. SD was then characterized by dissolution test, differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FT-IR). The spray dried SD of poloxamer 407 together with primary SD displayed highest dissolution rate of the drug of about 70% after 2 h. DSC, PXRD and FT-IR characterized the amorphous state and molecular dispersion of the drug in the SD. PK and PD studies in Sprague–Dawley rats revealed that the bioavailability of the drug using optimal SD was about twofold higher than that of reference product, and the irritation area of stomach was significantly reduced in the ulcer-induced rat model using optimal SD as compared to the reference product.

Preparation and valuation of a topical solution containing eutectic mixture of itraconazole and phenol

The purposes of this study were to prepare a topical solution containing itraconazole (ITR)-phenol eutectic mixture and to evaluate its ex vivo skin permeation, in vivo deposition and in vivo irritation. The eutectic mixture was prepared by agitating ITR and phenol (at a weight ratio of 1:1) together at room temperature. The effects of additives on the skin permeation of ITR were evaluated using excised hairless mouse skin. The in vivo skin deposition and skin irritation studies were performed in Sprague-Dawley rat and New Zealand white rabbit model. The permeability coefficient of ITR increased with addition of oleic acid in the topical solution. Otherwise, the permeability coefficient was inversely proportional to the concentration of the thickening agent, HPMC. The optimized topical solution contained 9 wt% of the ITR-phenol eutectic mixture, 9.0 wt% of oleic acid, 5.4 wt% of hydroxypropylmethyl cellulose and 76.6 wt% of benzyl alcohol. The steady-state flux and permeability coefficient of the optimized topical solution were 0.90 ± 0.20 μg/cm2·h and 22.73 ± 5.73 × 106 cm/h, respectively. The accumulated of ITR in the epidermis and dermis at 12 h was 49.83 ± 9.02 μg/cm2. The topical solution did not cause irritation to the skins of New Zealand white rabbits. Therefore, the findings of this study indicate the possibilities for the topical application of ITR via an external preparation.

Effect of electrokinetic stabilizers on the physicochemical properties of propofol emulsions

The aims of the present study were to elucidate the potential mechanism of propofol emulsion destabilization following the addition of lidocaine, and to evaluate the effects of various electrokinetic stabilizers on the physicochemical properties of lidocaine-propofol emulsions. The assessments included pH observations and determination of the maximum globule diameter (MGD) and zeta potential (ZP). The MGD of propofol emulsions increased up to several tens mum following the addition of 50 mg of lidocaine to 200mg of propofol, and the proposed destabilization mechanism involves localization of protonated lidocaine molecules between lecithin molecules in propofol emulsions, which consequently leads to increased ZP. The ZP of propofol emulsions containing acidic amino acid or neutral amino acid increased following the addition of lidocaine, and a charge reversal occurred. Therefore, the MGD of emulsions increased to several tens (m. However, the MGD of emulsions that contained basic amino acids or basic compounds remained below 5 (m, despite the addition of large amounts lidocaine (50 mg), and the ZP did not pass through the point of zero charge. In conclusion, our results provide not only further insight into the physical stability of propofol emulsions containing lidocaine, but also a better understanding of the administration of propofol in existing applications.