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

• YAKHAK HOEJI
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• v.36 no.6
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• pp.591-597
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• 1992

The organ distribution of $[^3H]$-methotrexate-lactosaminated bovine serum albumin conjugates ($[^3H]$-MTX-LBSA) was investigated to examine their role as a liver-specific anticancer drug. Synthesis of lactosaminated bovine serum albumin(LBSA) with BSA, lactose and sodium cyanoborohydride through reductive amination was followed by its conjugation with methotrexate (MTX) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), thereby synthesizing [$[^3H]$-MTX-LBSA conjugates. Organ distribution and plasma elimination profiles were studied in male Wistar rats after intravenous injection of [$[^3H]$-MTX-LBSA conjugates. The fates of $[^3H]$-MTX and the $[^3H]$-MTX-BSA conjugates´fates were also investigated for comparison. The results showed that the plasma level of $[^3H]$-MTX-LBSA conjugates declined more rapidly than those of $[^3H]$-MTX-BSA and their liver concentration was significantly higher than those of other treatment (p<0.01). In addition, their uptake compared to the amount taken up by the liver (1 : 33.1 at 10 min, 1 : 24.1 at 120 min). All these suggested that MTX-LBSA conjugate is one of the drug delivery system (DDS) that is advanced in concentrating MTX in the liver and minimizing the renal toxicity of MTX.

• The Journal of the Korean Society for Microbiology
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• v.22 no.3
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• pp.295-300
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• 1987

Salmonella strains isolated from blood in the Dong-san hospital, Taegu during the period from 1971 to 1986 were studied for species distribution, drug resistance, and R plasmids. The number of strains was 2,527 and all of them were classified into S. typhi and S. paratyphi A. Approximately 300 strains were isolated in the period from 1974 to 1976 and 1978, 268 in 1982, and 204 in 1983, but the numbers isolated in the 1980's have a tendency to decrease as compared with those of the 1970's. S. typhi occupied 85% or more of strains isolated until 1976, but the isolation frequency decreased yearly with some variation, and S. paratyphi A increased gradually from 1974. Only 4 strains of S. paratyphi A were resistant to some drugs, and the resistance was not transferred to E. coli by conjugation. S. typhi resistant to drugs were 15 in 1971 through 1973, 24 in 1974, and 13 in 1975, but afterwards only few resistant strains were isolated. These strains were resistant to two or more drugs; chloramphenicol(Cm), tetracycline(Tc), streptomycin(Sm), sulfisomidine(Su), ampicillin(Ap), and kanamycin(Km) and no strain resistant to other drugs tested was found. Strains resistant to 3 or less drugs didn't transfer the resistance to E. coli by conjugation. There were 15 strains resistant to four or more drugs, and were isolated in years from 1972 to 1976. These strains transferred the resistance to E. coli, and the resistance was considered to be mediated by R plasmids. Transfer frequency was higher at $25^{\circ}C$ than at $37^{\circ}C$ and patterns of transferred resistance were Cm, Tc, Sm, Su; Ap, Km; Cm. R plasmids having markers of Cm, Tc, Sm and Su were classified into Inc H1.

• Journal of Pharmaceutical Investigation
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• v.38 no.6
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• pp.393-398
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• 2008

A propofol delivery system was prepared using two biocompatible polymeric surfactants, poloxamer 407 and PEG 400. The nanoparticular stability of the micellar system was evaluated in terms of temperature change, storage time and composition. The particle size of the system was slightly increased with elevating temperature from $4^{\circ}C$ to $25^{\circ}C$, but its distribution was unimodal. At $40^{\circ}C$, the system presented a bimodal particle size distribution and the increase in the fraction of particles larger than 15 nm. This result might be due to the expansion of the nanoparticles through micellar swelling at the high temperature. It was found that propofol was gradually come out of the system, stored for a month at three different temperatures (4, 25 and $40^{\circ}C$). The drug loss was apparently dependent on temperature and the system composition. Increasing temperature induced the acceleration of the drug loss of $7{\sim}10%$ at $4^{\circ}C$ and $14{\sim}16 %$ at $40^{\circ}C$. This may be owing to the high diffusivity resulting from the swelling of the hydrophilic surface of the nanoparticle at high temperature. However, the addition of PEG 400 to the system led to the reduction of the drug loss. This result is associated with the previous investigation that PEG coverage decreased diffusion coefficient because of the formation of the denser structure on the surface of nanoparticulate. Nevertheless, the limited amount of PEG, less than 2% (w/v), should be used to prevent the precipitation and discoloration of the system.

• Journal of the Korean Chemical Society
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• v.53 no.6
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• pp.653-662
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• 2009

Developing effective tools for predicting absorption, distribution, metabolism, excretion properties and toxicity (ADME/T) of new chemical entities in the early stage of drug design is one of the most important tasks in drug discovery and development today. As one of these attempts, support vector machines (SVM) has recently been exploited for the prediction of ADME/T related properties. However, two problems in SVM modeling, i.e. feature selection and parameters setting, are still far from solved. The two problems have been shown to be crucial to the efficiency and accuracy of SVM classification. In particular, the feature selection and optimal SVM parameters setting influence each other, which indicates that they should be dealt with simultaneously. In this account, we present an integrated practical solution, in which genetic-based algorithm (GA) is used for feature selection and grid search (GS) method for parameters optimization. hERG ion-channel inhibitor classification models of ADME/T related properties has been built for assessing and testing the proposed GA-GS-SVM. We generated 6 different models that are 3 different single models and 3 different ensemble models using training set - 1891 compounds and validated with external test set - 175 compounds. We compared single model with ensemble model to solve data imbalance problems. It was able to improve accuracy of prediction to use ensemble model.

• Journal of the Korea Society of Computer and Information
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• v.29 no.2
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• pp.109-118
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• 2024

With the increasing number of social media users worldwide, cases of social media being abused to perpetrate various crimes are increasing. Specifically, drug distribution through social media is emerging as a serious social problem. Using social media channels, the curiosity of teenagers regarding drugs is stimulated through clever marketing. Further, social media easily facilitates drug purchases due to the high accessibility of drug sellers and consumers. Among various social media platforms, we focused on Instagram, which is the most used social media platform by young adults aged 19 to 24 years in South Korea. We collected four types of information, including profile photos, introductions, posts in the form of images, and posts in the form of texts on Instagram; then, we analyzed the similarity among each type of collected information. The profile photos and posts in the form of image were analyzed for similarity based on the SSIM(Structural Simplicity Index Measure), while introductions and posts in the form of text were analyzed for similarity using Jaccard and Cosine similarity techniques. Through the similarity analysis, the similarity among various accounts for each collected information type was measured, and accounts with similarity above the significance level were determined as the same drug sales account. By performing logistic regression analysis on the aforementioned information types, we confirmed that except posts in image form, profile photos, introductions, and posts in the text form were valid information for tracking the same drug sales account.

• Journal of Preventive Medicine and Public Health
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• v.9 no.1
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• pp.139-146
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• 1976

This survey attempted to determine the overall health situation in Kyunggido in terms of sickness prevalence, sickness distribution, demand for medical care by type, and utilization of medical care. The survey was conducted on 766 households, or 4,065 people, from July 1-31, 1975. The findings from the survey are as follows: 1) In terms of age distribution, 28.7% of the sample was from 10-19, the 40-49 age group was the next largest group, and those over 60 made up 7% of the sample. 2. The education distribution is as follows, 30.4% completed primary school, 22.4% had no formal education, 20.6% attended but did not onplete primary school, and 1.8% attended unversities or higher. 3) In terms of occupation, 55.9% were unemployed or family employees, which represents a large dependent population, 30.4% of the workers were employed in farming or fisheries. 4. The marital status is as follows, 58.8% of the women were married, 32.3% unmarried, and 7.5% divorced. 5) The prevalence rate of mouthy illness was 19.7% of 100 infant, 42.8% became fatally ill within the first year of life. This is a very high percentage compared with more developed nations. 6) Of those reportion on illness, 54.6% sought treatment. The rate of treatment was highest in infants at 77.7%. Us age increased, demand for treatment decreased to 43.1% for those in the aldest age group. The oldest age group also had the highest rate of non treatment at 56.8%. 7) The demand for medical care showed that 65.6% utilized drug stores, 20.2% utilized hospitals and clinics, 5.4% used herbdrug-stores and herb clinices, and 3.9% relied upon folk medicine and withch craft. 8) The utilization of medical facilties by sex is as follows, 65.1% of the men and 66.0% of the women used drug stores, and 19.2% of the men and 20.2% of the women used hospitals and clinics. However, more men (3.5%) were hospitalized than women (1.8%) 9) In terms of out-patient care, the largest age group of males was 10-19 (28.2%), and the largest age group of females was 0-9 (30.8%). There was no sex difference in the use of western pharmacies. Menaged 30-39 and women aged 50-59 were the most frequent users of herb clinics. 10) The rate of receiving treatment at drugstore hospitals went towards declining level in the second case of what While increaing much more at herb clinics and folk medicines in the second case than the first one. 11) After primary utilization of hospitals, 32.7%. of the adults aged 20-59 used drug-stores as a secondary source of care, and 12.8% of children and youth under age 20 continued receiving care at hospitals. 12) After primary utilization of drug-stores, 32.5 % of the adults continued to seek care at drug stores and 1.8% used hospitals. 4.2% of those over age 60 utilized folk medcine and witch craft.

• Biomolecules & Therapeutics
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• v.5 no.3
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• pp.284-291
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• 1997

The pharmacokinetics and tissue distribution of DWP20367 (1-cyclopropyl-6-fluoro-8-chloro-7-(2, 7-diazabicyclo[3,3,0]tract-4-ene-7-yl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid), a novel fluoroquinolone, were examined in rats and beagle dogs after a single intravenous and oral administration. Analysis of DWP20367 in plasma, tissue, and urine was determined by both HPLC and microbiological assay (bioassay). The plasma concentration-time curves of the drug in rats and beagle dogs were biexponentially declined. The terminal half-life (t$_{1}$2$\beta$/) of the drug in rats was about 60.1 $\pm$7.3 min (i.v.) and 61.3 $\pm$ 12.4 min (p.o.) in bioassay, and 86.3 $\pm$19.8 min (i.v.) and 50.9$\pm$ 14.9 min (p.o.) in HPLC. In beagle dogs, half-life of the drug determined by bioassay was about 121.8$\pm$6.2 min (i.v.) and 111.0$\pm$7.6 min (p.o.). The volume of distribution at steady-state (Vd$_{ss}$ ) was 243.8$\pm$74.1 ml/kg (bioassay) and 339.2$\pm$84.3 ml/kg (HPLC) in rats, and 1587.5 $\pm$536.9 ml/kg (bioassay) in beagle dogs. The total body clearance (Cl$_{t}$) of DWP20367 was 3.4 $\pm$ 0.4 ml/min/kg (bioassay) and 2.4$\pm$0.4 ml/min/kg (HPLC) in rats, and 12.3$\pm$ 1.0 ml/min/kg (bioassay) in beagle dogs, respectively. The extent of bioavailability after oral administration was 89.1%(bioassay) and 79.9% (HPLC) in rats, and 78.7% (bioassay) in beagle dogs. Urinary recovery (24-h) assayed by bioassay was 0.7% (p.o.) and 1.2% (i.v.) in rats, and 0.8% (p.o.) and 1.0% (i.v.) in beagle dogs. In rats, 24-h fecal recovery determined by bioassay was 11.2% (p.o.) and 0.1% (i.v.). Rat and human serum protein binding ratios at 2$\mu$g/ml were about 90~91%. This drug determined by bioassay was also distributed by the order of liver, kidney, lung, heart, spleen and muscle 30 min after oral administration.on.

• Journal of Pharmaceutical Investigation
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• v.25 no.3
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• pp.249-264
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• 1995

Although liposome has many advantages as a pharmaceutical dosage form, its application in the industrial field has been limited because of some problems such as preparation method, reproducibility, scale-up, stability and sterilization etc. Liposomes prepared by microemulsification method had defined size, narrow size distribution, reproducibility and high entrapment efficiency. For enhancing the stability, the dry form of liposome was recommended. These types of liposome are proliposome and freeze-dried liposome. The liposome must have some properties for preparing of freeze-dried liposome; small size $(50{\sim}200\;nm)$, narrow size distribution and cryoprotectant. In this experiment, the liposomes containing 5-Fluorouracil(5-FU) and its prodrug(pentyl-5-FU-1-acetate; PFA, hexyl-5-FU-1-acetate; HFA) were made with soybean phosphatidylcholine, cholesterol, stearylamine(SA) and dicetyl phosphate(DCP) employing hydration method or microemulsification method using $Microfluidizer^{TM}$. Both or liposome types were MLV and MEL. After preparation, freeze drying and rehydration were performed. In the process of freezing, trehalose(Tr) was added as a cryoprotectant. Their evaluation methods were as follows; entrapment efficiency, mean particle size and size distribution, dissolution test, retain of entrapment efficiency and turbidity after freeze-drying. The results are summarized as belows. The entrapment efficiency of 5-FU was dependent on total lipid concentration and cholesterol content but that of PFA and HFA was decreased when cholesterol was added. When DCP and SA were added, entrapment efficiency was decreased. As the partition coefficient of drug was increased, entrapment efficiency was increased. Under the same condition, entrapment efficiency of MEL is similar to that of MLV. The mean particle size and size distribution of MEL were smaller than those of MLV. Dissolution rates of drug from both liposome types were comparatively similar. Dissolution rates of drugs with serum and liver homogenate were faster than without these material. After preparation of liposome, free drug was removed efficiency by Dowex 50W-X4. When liposome was freeze-dried and then rehydrated in the presence of Tr, characteristics of liposome were maintained well in MEL than MLV. Tr Was used successfully as a cryoprotectant in the process of freeze drying and the optimal ratio of Tr:Lipid was 4:1(g/g).

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.287-287
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• 1996

Long-circulating liposomes have prompted interests in using them as a drug delivery system. This improvements in delivery has been thought to be the results from sustained action of liposomes in plasma without RES uptake. Although methotrexate(MTX) has been one of the most widely used antineoplastc drug, its use was limited by prompt RES uptake. The purpose of this study was to prepare long-circulating liposomes for MTX using highly water-soluble polymer (PEG-PE). In vitro, release of MTX from liposomes in phosphate buffer (pH 7.4), rat liver homogenate, and rat plasma was investigated. The pharmacokinetics and organ distribution of fee drug, conventional and long-circulating liposomes were also compared with one another after intravenous administration to rats.