• Journal of Pharmaceutical Investigation
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• v.22 no.3
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• pp.205-210
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• 1992

In order to develop a controlled-release oral drug delivery system (DDS) of theophylline (TP), microporous membrane-coated tablets were prepared and evaluated in vitro and in vivo. Rapidly water-soluble core tablets of TP (300 mg) were prepared by wet granulation and compression technique, Then the core tablets were spray-coated with polyvinylchloride (PVC) in which micronized sucrose particles were dispersed. Effect of formula compositions of coating suspensions on the pharmaceutical characteristics such as membrane strength and dissolution was investigated in vitro. The membranes remained unbroken in pH 1.2 buffer at $37^{\circ}C$ at least for 2 hours after the disintergration test. TP was released from the coated-released tablets at a zero-order rate over 8 hours. The release at pH 1.2 and 4.0 was similar in rate but a little more rapid than that at pH 6.8. The coated tablets were administered to three healthy male volunteers and their saliva profiles of TP were compared with those from the commercial sustained release TP tablets such as Slobid and Asconthin. Saliva TP concentrations from the coated tablets were successfully sustained over 48 hours after the dosing and were comparable to those of the commercial sustained-release tablets. The membrane-coating technique is very simple and does not need any sophisticated equipments. In this respect, the membrane-coated tablets may be superior to the commercial sustained-release tablets and this technique is worth adopting by the pharmaceutical industries.

• 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.

• Fire Science and Engineering
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• v.31 no.5
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• pp.19-27
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• 2017

The effects of changes in area and location of fire source, fire growth rate, and volume of compartment on the major fire characteristics, including heat release rate, in closed compartment fires were examined. To this end, a fire simulation using Fire Dynamics Simulator (FDS) was performed for ISO 9705 room with a closed opening. As main result, it was found that the changes in the area and location of fire source did not significantly affect the thermal and chemical characteristics inside the compartment, such as maximum heat release rate, total heat release, maximum temperature at upper layeras well as species concentrations. However, increasinthe fire growth rate and volume of compartment resulted in increase of the maximum heat release rate and total heat release, decrease in the limiting oxygen concentration and increase in the maximum CO concentration. Finally, a methodology for the application of fire growth curves to closed compartment fires was proposed by deriving the correlation of the maximum heat release rate expressed as a function of the fire growth rate and the volume ratio of compartment based on the ISO 9705 room.

• YAKHAK HOEJI
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• v.58 no.4
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• pp.245-249
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• 2014

Murrayafoline-A (1-methoxy-3-methylcarbazole) is a monomeric carbazole alkaloid found in Murraya euchrestifolia HAYATA and Glycosmis stenocarpa. We have recently shown that murrayafoline-A has positive inotropic effect in isolated rat ventricular myocytes. To know possible mechanisms for the positive inotropic effect of murrayafoline-A we examined the effects of murrayafoline-A on in situ behavior of cardiac $Ca^{2+}$ release units ('$Ca^{2+}$ sparks') and sarcoplasmic reticulum (SR) $Ca^{2+}$ loading using confocal $Ca^{2+}$ imaging method in single rat ventricular myocytes. Murrayafoline-A significantly increased the frequency (events/($10^3{\mu}m^2{\cdot}s$)) of $Ca^{2+}$ sparks in a concentration-dependent manner, with an $EC_{50}$ of $28{\pm}6.4{\mu}M$ and a maximal ~twofold change. The $Ca^{2+}$ content in the SR, measured as caffeine (10 mM)-induced $Ca^{2+}$ transient, was significantly increased by murrayafoline-A (${\approx}$116% and ${\approx}$123% of control at 25 and 100 ${\mu}M$, respectively). In addition, murrayafoline-A significantly increased the fractional $Ca^{2+}$ release, suggesting increase in the efficacy of $Ca^{2+}$ release at given SR $Ca^{2+}$ loading. These results suggest that murrayafoline-A may enhance contractility via increase in $Ca^{2+}$ release from the SR through the ryanodine receptors in ventricular myocytes.

• Biomedical Science Letters
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• v.12 no.2
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• pp.57-63
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• 2006

Deazaadenosine analogs such as 3-deazaadenosine (DZA), 3-deazaaristeromycin (DZAri) and ara-3-deazaadenine (DZAra-A) were developed as inhibitors of S-adenosylhomocysteine (Ado-Hcy) hydrolase (EC 3.3.1.1). These analogs were reported to induce apoptosis in human and murine leukemic cells. But, the mechanism involved in this apoptosis was not clarified yet. In the present study, we analyze the apoptosis induced by deazaadenosine analogs in human cervival cancer cell line, HeLa and the effect of Bcl-2 on this apoptosis. Whereas neither DZAri nor DZAra-A showed inhibitory effect on HeLa cell growth, DZA induced apoptosis in HeLa cells accompanied by cytochrome c release and activation of various caspases such as caspase-2,-8,-9 and -3. In HeLa-bcl-2 cell line, a stable transfectant of HeLa cell to overexpress Bcl-2, cytochrome c release, activation of all these caspases and the resulted apoptosis by DZA were completely prevented. By in vitro assay of cytochrome c release, in addition, DZA induced cytochrome c release from purified mitochondria of HeLa-pcDNA3 cells, but not HeLa-bcl-2 cells, even in the absence of cytosolic fraction. Therefore, it can be suggested that DZA might damage directly mitochondria leading to activate intrinsic pathway of caspase and thus induce apoptosis. DZA-induced apoptosis in HeLa cells may be in a bcl-2-inhibitable manner and irrelative of Ado-Hcy hydrolase.

• The Korean Journal of Pain
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• v.13 no.1
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• pp.60-66
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• 2000

Background: For terminal cancer pain management, controlled-release oral morphine (morphine sulfate tablet, MST) is a simple and convenient regimen. Recently, fentanyl transdermal therapeutic system (F-TTS, transdermal fentanyl) has been developed and became one of the alternative ways of providing adequate pain relief. This open prospective study was designed to compare the analgesic efficacy and safety of MST and transdermal fentanyl in the management of terminal cancer pain. Methods: In this open comparative and randomized study, 64 terminal cancer patients received one treatment for 15 days, controlled-release oral morphine (MST group) or fentanyl transdermal therapeutic system (F-TTS group). Daily diaries about the vital sign, visual analogue scale (VAS) for pain, opioids requirement, co-anagesics, adjuvant drugs and adverse effects were completed with 24 patients in MST group, 18 patients in F-TTS group. Results: The majority of patients in both treatment groups were late-stage cancer and their distribution was not different in both groups. Daily opioids requirement was 126.4 mg in MST uced in F-TTS group (P<0.05). The incidence of nausea, vomiting and constipation was lower in F-TTS group (P<0.05). Patients satisfaction was similar, but F-TTS patient group favored continous use of same treatment compared with MST group after the study was finished. Conclusions: Transdermal fentanyl seems to be safe and similar analgesic effect to controlled-release oral morphine for the control of the terminal cancer patients. However, transdermal fentanyl provides a simpler and more convenient especially in respect to constipation, nausea & vomiting. To determine the exact analgesic effect, cost-effectiveness and complications, controlled trials should be followed.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.90-99
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• 1994

One of the major phenomena occurring in defective fuel rods is the oxidation of UO$_2$ fuel pellets from UO$_2$ to UO$_{2+}$x/ by the oxygen Produced from the dissociation of the steam in the Pellet-to-clad gap, which leads to the enhancement of fission gas release. In this paper, the oxidation kinetics of defective fuel rods was analyzed on the basis of operating conditions of the reactor and defective fuel rod itself. Oxidation kinetics of the fuel pellet was determined under the assumption that the gap is filled with the saturated steam of 150 atm and an enhancement factor for fission gas release was introduced to take into account the effect of fuel oxidation on fission gas release. Comparison with experimental data shows that the enhancement factor predicts well the increased fission gas release due to the oxidation of UO$_2$fuel pellets.

• Journal of Pharmaceutical Investigation
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• v.41 no.6
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• pp.363-369
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• 2011

In this study, we demonstrated the release behavior of carvedilol with the content of polyvinylpyrrolidone K-30 (PVP K-30) and the effect of citric acid and fumaric acid as acidifiers on the release behavior of drug. In addition, it tries to inquire into the release behavior difference of the carvedilol according to the manufacturing method. The release behavior of the tablets was compared with Dilatrand$^{(R)}$ in the simulated gastric fluid (pH1.2). Differential scanning calorimeter (DSC), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) were characterized for the physicochemical properties of the tablets. In case of mixing the carvedilol and PVP K-30, in case the ratio of the carvedilol and PVP K-30 was 1:5, the release behavior was the highest among. As well as the dissolution rate of tablets manufactured by lyophilization and rotary evaporator was higher than physical mixture. The dissolution rate of containing acidifiers was more improved. But, rather the excessive amount of the acidifier addition reduced the dissolution rate.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.147-154
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• 2018

Currently, to overcome low therapeutic efficiencies and side effects of anticancer agents, the study of drug carrier based on polymers have been consistently investigated. Although the traditional drug carrier based on polymers displayed an excellent result and significant progress, there has been a problem with the side effect and low therapeutic efficiency because of the premature drug release before reached to the targeted region by the low stability in blood stream and sustained drug release. In this review article, to improve the problem of inefficient drug release, methods were suggested, which can maximize the therapeutic efficiency by increasing the stability in the blood stream and triggering drug release at the target site by introducing a stimuli-responsive substance to the non-toxic and biocompatible natural polymer chitosan.

• Journal of Adhesion and Interface
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• v.12 no.4
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• pp.144-150
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• 2011

The effect of low profile agent and release agent on the surface and mechanical properties of bulk mold compound were investigated. Atomic content and contact angle of surface were characterized using X-ray photoelectron spectroscopy and contact anglemeter. Surface morphology and surface roughness were obtained using field emission scanning electron microscope and atomic force microscope, respectively. As increasing the low profile agent from 0 to 9.2 wt%, the volume shrinkage and surface roughness decreased from 0.35% to 0.05%, and from $0.27{\mu}m$ to $0.12{\mu}m$, respectively. The increase of release agent from 1.8 wt% to 3.6 wt% resulted in the migration of release agent to sample surface and it increased the surface roughness. The flexural strength and impact strength were decreased approximately 30% as the low profile agent increasing from 5.0 wt% to 9.0 wt%.