• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.278-278
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• 1996

Judging from hydrocortisone concentration in dosing area, the extent of absorption was reduced in the liposome-gel formulation. However, higher and sustained skin concentrations of hydrocortisone were achieved for the liposome-gel as compared to the ointment. Drug concentration in both viable and deep skin reached its maximum within 0.5 h after application of both formulations to both skin types. Drug concentrations in both skins from the ointment declined with time, while those from the liposome-gel were greatly sustained. The sustainment by the liposome-gel was more remarkable in the viable skin than in the deep skin. Drug concentration in the viable skin could be maintained at a nearly constant level for over 8 h by applying the liposome-gel. As a result, a 5-fold higher viable skin drug concentration was obtained from the liposome-gel than from the ointment at 8 h after the application to the SC-removed skin. However, the plasma concentration of hydrocortisone at 4 h from the liposome-gel was only one-fourth (p<0.01) the value from the ointment when the drug was applied to the SC-removed skin, consistent with. the lower urinary (one-third, p<0.05) and fecal (one-half, p＜0.05) excretion. Conclusions : Retarded diffusion of the drug from the skin to the systemic blood stream appears to be a potential factor in the sustained skin concentration of hydrocortisone from the liposome-gel, Interaction of hydrocortisone in the skin with phosphatidylcholine, a component of the liposomes and skin, may well be a factor in retarding the diffusion of the drug in the skin.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.541-549
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• 2020

The Drug Delivery System (DDS) is defined as a technology for designing existing or new drug formulations and optimizing drug treatment. DDS is designed to efficiently deliver drugs for the care of diseases, minimize the side effects of drug, and maximize drug efficacy. In this study, the optimization of tripolyphosphate (TPP) concentration on the size of Chitosan nanoparticles (CNPs) produced by crosslinking with chitosan was measured. In addition, the characteristics of Fe₃O₄-CNPs according to the amount of iron oxide (Fe₃O₄) were measured, and it was confirmed that the higher the amount of Fe₃O₄, the better the characteristics as a magnetic drug carrier were displayed. Through the ninhydrin reaction, a calibration curve was obtained according to the concentration of γ-aminobutyric acid (GABA) of Y = 0.00373exp(179.729X)-0.0114 (R² = 0.989) in the low concentration (0.004 to 0.02 wt%) and Y = 21.680X-0.290 (R² = 0.999) in the high concentration (0.02 to 0.1 wt%). Absorption was constant at about 62.5% above 0.04 g of initial GABA. In addition, the amount of GABA released from GABA-Fe₃O₄-CNPs over time was measured to confirm that drug release was terminated after about 24 hr. Finally, GABA-Fe₃O₄-CNPs performed under the optimal conditions were spherical particles of about 150 nm, and it was confirmed that the properties of the particles appear well, indicating that GABA-Fe₃O₄-CNPs were suitable as drug carriers.

• Macromolecular Research
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• v.10 no.5
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• pp.246-252
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• 2002

In order to the development of the delivery device of long-acting local anesthetics for postoperative analgesia and control of chronic pain of cancer patient, fentnyl-loaded poly (L-lactide-co-glycolido) (PLGA, molecular weight, 5,000 g/mole; 50 : 50 mole ratio by lactide to glycolide) microspheres (FMS) were studied. FMS were prepared by an emulsion solvent-evaporation method. The influence of several preparation parameters such as initial drug loading, PLGA concentration, emulsifier concentration, oil phase volume, and fabrication temperature has been investigated on the fentanyl release profiles. Generally, the drug showed the biphasic release patterns, with an initial diffusion followed by a lag period before the onset of the degradation phase, but there was no lag time in our system. Fentanyl was slowly released from FMS over 10 days in vitro with a quasi-zero order property. The release rate increased with increasing drug loading as well as decreasing polymer concentration with relatively small initial burst effect. From the results, FMS may be a good formulation to deliver the anesthetic for the treatment of chronic pain.

• Journal of Pharmaceutical Investigation
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• v.36 no.4
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• pp.245-251
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• 2006

The novel microsphere blending and multiple emulsion method by single process was tried to prepare sustained release microspheres which release a physiologically active substance for long periods of time. A drug was separately dissolved in each of two or more oils containing biodegradable polymers to give the primary oil phases. The primary oil phases were dispersed in single aqueous phase in succession. From the drug-dispersed solution, the organic solvent was removed to produce microspheres. The accelerated drug release from the microsphere formulation prepared by single process through the multiple emulsion method was very similar to a physical blending of separately prepared microspheres using the same polymers. But long term release was not same. In this study, leuprorelin acetate loaded poly(lactide-co-glycolide) microsphere formulation for one-month delivery was developed by the multi-emulsion method followed by solvent extraction/evaporation method.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4035-4040
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• 2012

Presented study describes the synthesis of photo cross-linkable and water soluble hydroxyethyl starch hydroxyethyl methacrylate (HESHEMA) samples with different degree of substitution (DS) by functionalization of hydroxyethyl starch (HES) with hydroxyethyl methacrylate (HEMA) or hydroxyethyl methacrylate carbonylimidazole (HEMACI) in DMSO using two different routes. It was revealed that the reaction time for HESHEMA synthesis can be reduced from 5 days to 24 h by conducting the reaction at $80^{\circ}C$ instead of at room temperature. Solubility of HESHEMA was found to be dependent on DS which in turn was dependent on ratio between HES and HEMA or HEMACI. HESHEMA samples with DS > 0.24 depicted insoluble in water, whereas the samples with DS < 0.05 did not form appreciable gel. HESHEMA samples with appropriate DS were converted into hydrogels by cross-linking polymer chains under UV radiations and resulting HESHEMA hydrogels showed swelling up to 1200%. Application of HESHEMA in controlled drug delivery was investigated by diffusion based encapsulation of Ondansetron, a serotonin 5-$HT_3$ receptor antagonist drug, mainly used for nausea and vomiting treatment.

• Translational and Clinical Pharmacology
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• v.25 no.1
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• pp.15-20
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• 2017

This study was performed to evaluate the use of vibrating microneedles for the transdermal delivery of vitamin C. The microneedles were designed to vibrate at three levels of intensity. In vitro permeation by vitamin C was evaluated according to the specific conditions such as vibration intensity (levels 1, 2 and 3), application time (1, 3, 5, 7 and 10 min), and application power (500, 700 and 1,000 g). The highest permeation of vitamin C was observed at level 3 of vibration intensity, 5 min of application, and 1,000 g of application power. Vitamin C gel showed no cytotoxic effect against Pam212 cells or skin irritation effects. A pharmacokinetic study of the gel in rats was conducted under optimized conditions. The $AUC_{0-{\infty}}$ and $C_{max}$ increased 1.35-fold and 1.44-fold, respectively, compared with those after vitamin C gel without application with vibrating microneedles. The present study suggests that vibrating microneedles can be used to facilitate the skin permeability of vitamin C under optimal conditions.

• Journal of Pharmaceutical Investigation
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• v.35 no.5
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• pp.369-373
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• 2005

The objectives of the current work is to understand the factors impacting the formulation and performance of a Carbopol mucoadhesive buccal delvery system for a model peptide drug, $[D-Ala{^2},\;D-Leu{^5}]$enkephalin (DADLE, Mw=569.7) with comparable chemical and enzymatic stability. Specifically, in vitro buccal DADLE delivery from the cross-linked poly(acrylic acid) (PAA) hydrogel system was characterized. In addition, the influences of several penetration enhancers on the ex vivo buccal absorption of DADLE were also studied. In this study, the PAA hydrogels generally swell to 100% of their original weight in the phosphate pH 7.4 buffer. The water penetration into the PAA hydrogel occurred based on a zero-order kinetics for the first 60 min and steadily decreased afterwards. From the release study, it can be seen that the initial DADLE release was so rapid and the rate of release of DADLE decreased as the time elapsed. The porcine buccal tissue was found to be permeable to DADLE with a flux value of $0.07%/cm{^2}/hr({\pm}0.01\;SD)$. From the ex vivo diffusion study, it was found that sodium taurodihydrofusidate showed a greater degree of enhancement compared to the phospholipids with an Enhancement Ratio (ER) of 8.7 compared to 2.7 and 1.9 for didecanoylphosphatidylcholine and lysophosphatidylcholine, respectively. The work encompassed within this paper has demonstrated the feasibility of using the PAA hydrogel delivery system with its good mucoadhesive properties for the buccal delivery of peptides.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.2
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• pp.286-290
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• 2012

The majority of laboratory animals were transported from commercial breeders to a research facility by ground transportation. During the transportation, many biological functions and systems can be affected by stress. In this experiment, the change of body weight during the transportation was measured and the recovery periods from the transportation stress established based on the body weight changes. Total 676 laboratory animals which were aged between 3 to 9 wk old were studied. The transportation time taken from container packing to unpacking the container was approximately 24 h. The temperature of animal container was constantly maintained by air-conditioning and heating equipment. Rats were found to be more sensitive than mice. The body weight of rats was significantly decreased 3.71% (p<0.05) compared to the body weight of mice which decreased 0.9% There was no significant difference between the strains in the same species. When the changes of body weights were compared between delivery days, C57BL/6 mice showed the most variable changes compared to other species and strains. Consequently, C57BL/6 was more sensitive to stress than the other strains and the transportation process needs to be standardized to reduce between day variability. To establish the recovery periods from transportation stress, the body weight changes were measured during the acclimation period. Although the body weight of animals decreased during transportation, animals recovered their weight loss after the next day.

• Journal of Pharmaceutical Investigation
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• v.28 no.2
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• pp.87-92
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• 1998

Kojic acid (KA) is an antimelanogenic agent which has been widely used in cosmetics to whiten the skin color. However, it has the drawbacks of the skin irritancy and the instability against the pH, temperature, and light. In order to overcome these problems, various topical gels and multiple emulsion creams which can control the release of active ingredient, KA, were formulated employing cream bases of mineral oil with caprylic capric triglyceride and hydrophilic polymers such as chitosan, carbopol. and pluronics. Using Franz diffusion cells mounted with a synthetic cellulose membrane (MWCO 12,000), drug release characteristics of the formulations were evaluated by the HPLC assay of KA concentration in the receptor compartment of pH 7.4 phosphate buffered saline solution. Drug release from chitosan-based gels (ChitoGel) obeyed to the first order kinetics with a rapid release especially in the initial period. However, pluronic-based gels (PluGel) and carbopol-based gels (CarboGel) revealed controlled release of drug to some extent, followed by the square root-time kinetics. Moreover, the release of KA was further controlled with the W/O/W multiple emulsion creams (MultiCream), showing the apparent zero order release kinetics by virtue of dynamic ratecontrolling membrane of the oil layer. The flux $(J,\;{\mu}g/cm^2/hr)$ of ChitoGel. CarboGel. PluGel. and MultiCream in the initial period of 6hr were 73.30, 28.67. 24.04 and 7.72, respectively. On the other hand, the skin irritancy score of ChitoGel and MultiCream were observed as 2.5 and 2.3 respectively, in the rabbit skin irritation test. Although there were insignificant differences at p<0.05 between those formulations, it was possible to conclude that the W/O/W multiple emulsion creams containing KA might be a good candidate for an antimelanogenic drug delivery system due to the controlled release of acidic drug molecules.

• KSBB Journal
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• v.11 no.6
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• pp.676-680
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• 1996

The characteristics of controlled drug release were studied for a biodegradable drug delivery system. A biodegradable chitosan matrix was prepared after swelling chitosan with 10%-acetic acid and adding sulfadiazine. The release behavior of sulfadiazine from the chitosan matrix was studied using the Higuchi's diffusion controlled model in phosphate buffer solutions of pH 7.4 and pH 1.2. The drug release time was delayed by increasing the content of sulfadiazine. The drug release at pH 7.4 was more delayed than that at pH 1.2. The reason is that chitosan has greater swelling abilities at low pH than at high pH. The apparent release rate constant(K) increased as the concentration of drug increased. In shoat, the formulation the biodegradable chitosan matrix to suppress the burst effect of drug release mechanism, which led to a sustained release pattern.