• 분석과학
• /
• 제34권2호
• /
• pp.46-55
• /
• 2021

Evaluation of drug-excipient compatibility is one of the basic steps in the preformulation of pharmaceutical dosage forms. Some reactive excipients have been known so far which may cause stability problems for drug molecules in pharmaceutical dosage forms. The aim of this study was to evaluate drugexcipient compatibility of gliclazide with some common pharmaceutical excipients, known for their ability to incorporate in drug-excipient interactions. Binary mixtures were prepared using lactose, magnesium stearate, polyvinylpyrrolidone, sodium starch glycolate, polyethylene glycol 2000 and dicalcium phosphate. Based on the results; gliclazide was incompatible with all tested excipients; but not with dicalcium phosphate. DSC (Differential Scanning Calorimetry) results were in accordance with HPLC (High Pressure liquid chromatography) data and were more predictive than FTIR (Fourier Transform Infrared Spectroscopy). Drug and reactive excipients incompatibility was fully discussed and documented. It is advisable to avoid incompatible excipients or carefully monitor the drug stability when incorporating such excipients in final formulation designs.

• Advances in nano research
• /
• 제12권4호
• /
• pp.405-414
• /
• 2022

In this study, the elastic plane problem of a layered composite containing an internal or edge crack perpendicular to its boundaries in its lower layer is examined using numerical analysis. The layered composite consists of two elastic layers having different elastic constants and heights. Two bonded layers rest on a homogeneous elastic half plane and are pressed by a rigid cylindrical stamp. In this context, the Finite Element Method (FEM) based software called ANSYS is used for numerical solutions. The problem is solved under the assumptions that the contacts are frictionless, and the effect of gravity force is neglected. A comparison is made with analytical results in the literature to verify the model created and the results obtained. It was found that the results obtained from analytical formulation were in perfect agreements with the FEM study. The numerical results for the stress-intensity factor (SIF) are obtained for various dimensionless quantities related to the geometric and material parameters. Consequently, the effects of these parameters on the stress-intensity factor are discussed. If the FEM analysis is used correctly, it can be an efficient alternative method to the analytical solutions that need time.

• 분석과학
• /
• 제36권4호
• /
• pp.180-190
• /
• 2023

The presence of process related impurities in any drug or the drug product was associated with its safety, stability and efficacy. The overall literature survey proved that there is no method published on the assessment of process related impurities in brigatinib. In this study, a simple, reliable and stable HPLC qualitative method was reported for quantification of process related impurities with easy and quick extraction procedure. The impurities along with standard brigatinib was resolved on Lichrospher^® C18 (250 mm × 4.6 mm; 5 ㎛ particle size) column in room temperature using methanol, acetonitrile, pH 4.5 phosphate buffer in 55:25:20 (v/v) at 1.0 mL/min as mobile phase and UV detection at 261 nm. The method produces well resolved peaks at retention time of 4.60 min, 12.28 min, 3.37 min, 7.34 min and 8.39 min respectively for brigatinib, impurity A, B, C and D. The method produces a very sensitive detection limit of 0.0065 ㎍/mL, 0.0068 ㎍/mL, 0.0053 ㎍/mL and 0.0058 ㎍/mL for impurity A, B, C and D respectively with calibration curve linear in the concentration range of 22.5-135 ㎍/mL for brigatinib and 0.0225-0.135 ㎍/mL for impurities. The method produces all the validation parameters under the acceptable level and doesn't produces any considerable changes in peak area response while minor changes in the developed method conditions. The method can effectively resolve the unknown stress degradation products along with known impurities with less % degradation. The method can efficiently resolve and quantify the impurities in formulation and hence can suitable for the routine quality analysis of brigatinib in raw material and formulation.

• 한국정보처리학회논문지
• /
• 제7권2호
• /
• pp.477-487
• /
• 2000

본 논문에서는 체적 시각화 과정을 이론적으로 고찰하여 시각화 모델을 제시하고 그 모델로 유도된 관계로부터 미분 방정식을 이용하여 분석적 체적 시각화 해법을 구하였다. 이 분석적 방법을 제적 시각화의 대표적인 방법인 Levoy의 이산적 광선 추적법과 비교하여 본 연구에서 제시한 방법의 특수한 형태가 Levoy의 이산적 방법임을 보였다. 그리고 체적 데이터를 시각화기 위해서는 사용자가 시각화하기를 원하는 부위를 선택하고 이 부분만을 추출하는 영역 분할 작업이 필요하다. 본 논문에서는 영역확장법에 기반을 둔 효율적인 3차원 영역 분할 기법을 개발하여 위의 분석적인 방법을 이용하여 3차원 제적 데이터의 시각화를 위한 시스템을 구현하였다. 그리고 본 접근법에 대한 의의와 유용함에 대한 가설적인 결론을 구현된 시스템을 이용한 실험에 근거하여 유도하였다. Lovoy의 이산적인 방법과 분석적인 방법을 같은 데이터에 대해 3차원 영역 분할 수행 후 적용한 실험은 분석적인 방법이 이산적인 방법에 비해 렌더링된 이미지의 질이 더 좋음을 보여준다.

• 분석과학
• /
• 제32권4호
• /
• pp.147-154
• /
• 2019

Ampicillin and Sulbactam (2:1, w/w) are combined in formulation to provide broader antibacterial action in treatment of many infections. The development of analytical method for simultaneouly determine these two compounds was difficult because of the differences in their chemical structures and ratio in the formulation. Current published methods still have some limitations. In this study, we developed an alternative high-performance liquid chromatography (HPLC) assay method for simultaneously determination of ampicillin sodium and sulbactam sodium in powder for injection. Method validation of HPLC method was conducted to determine linearity, precision, accuracy, system suitability, robustness. The linearity of the calibration curves in the desired concentration range was good ($r^2$> 0.9994). RSDs of intra-day and inter-day precision obtained were less than 2.00 %. Accuracy was obtained with the recoveries in range of 98.42 % and 101.36 %. As a result of system suitability, RSD of both retention time and the peak area obtained were not more than 1.0 %. The values of plate number were more than 7000 and symmetric factors obtained were 0.8. As intermediate-precision and robustness of the developed assay, it could be expected to become valuable tools for revising the Korean Pharmacopoeia (KP XI).

• Earthquakes and Structures
• /
• 제16권3호
• /
• pp.279-293
• /
• 2019

The overall seismic performance of existing pre 1960-70s reinforced concrete (RC) structures is significantly affected by the inadequate length of columns' lap-spliced reinforcement. Due to this crucial structural deficiency, the cyclic response is dominated by premature bond - slip failure, strength and stiffness degradation, poor energy dissipation capacity and low ductility. Recent earthquakes worldwide highlighted the importance of improving the load transfer mechanism between lap-spliced bars, while it was clearly demonstrated that the failure of lap splices may result in a devastating effect on structural integrity. Extensive experimental and analytical research was carried out herein, to evaluate the effectiveness and reliability of strengthening techniques applied to RC columns with lap-spliced reinforcement and also accurately predict the columns' response during an earthquake. Ten large scale cantilever column subassemblages, representative of columns found in existing pre 1970s RC structures, were constructed and strengthened by steel or RC jacketing. The enhanced specimens were imposed to earthquake-type loading and their lateral response was evaluated with respect to the hysteresis of two original and two control subassemblages. The main variables examined were the lap splice length, the steel jacket width and the amount of additional confinement offered by the jackets. Moreover, an analytical formulation proposed by Tsonos (2007a, 2019) was modified appropriately and applied to the lap splice region, to calculate shear stress developed in the concrete and predict if yielding of reinforcement is achieved. The accuracy of the analytical method was checked against experimental results from both the literature and the experimental work included herein.

• Structural Engineering and Mechanics
• /
• 제87권2호
• /
• pp.173-189
• /
• 2023

For a given structural geometry, the stiffness and damping parameters of the soil and the dynamic response of the structure may change in the face of an equivalent linear soil behavior caused by a strong earthquake. Therefore, the influence of equivalent linear soil behavior on the impedance functions form and the seismic response of the soil-structure system has been investigated. Through the substructure method, the seismic response of the selected structure was obtained by an analytical formulation based on the dynamic equilibrium of the soil-structure system modeled by an analog model with three degrees of freedom. Also, the dynamic response of the soil-structure system for a nonlinear soil behavior and for the two types of impedance function forms was also analyzed by 2D finite element modeling using ABAQUS software. The numerical results were compared with those of the analytical solution. After the investigation, the effect of soil nonlinearity clearly showed the critical role of soil stiffness loss under strong shaking, which is more complex than the linear elastic soil behavior, where the energy dissipation depends on the seismic motion amplitude and its frequency, the impedance function types, the shear modulus reduction and the damping increase. Excellent agreement between finite element analysis and analytical results has been obtained due to the reasonable representation of the model.

• 분석과학
• /
• 제36권6호
• /
• pp.281-290
• /
• 2023

Zidovudine is an antiretroviral agent prescribed for the prevention and treatment of human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). It is typically recommended to be used in combination with other antiretroviral drugs. Zidovudine has the potential to generate N-nitrosodimethylamine (NDMA) in the presence of dimethylamine and nitrite salt under acidic reaction conditions during the drug manufacturing process. NDMA is a potent human carcinogen that may be detected in drug substances or drug products. An analytical method was developed to determine NDMA in pharmaceuticals including zidovudine using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The analysis involved reversed-phase chromatography on a Kinetex F5 column with a mobile phase comprising water-acetonitrile mixtures. The detection of positively charged ions was conducted using atmospheric pressure chemical ionization (APCI). The calibration curve demonstrated excellent linearity (r = 0.9997) across the range of 1-50 ng/mL with a highly sensitive limit of detection (LOD) at 0.3 ng/mL. The developed method underwent thorough validation for specificity, linearity, accuracy, precision, robustness, and system suitability. This sensitive and specific analytical method was applied for detecting NDMA in zidovudine drug substance and its formulation currently available in the market, indicating its suitability for drug quality management purposes.

• 혜화의학회지
• /
• 제23권1호
• /
• pp.93-104
• /
• 2014

Glycyrrhizae Radix et Rhizoma has been extensively used by human beings as a medicinal herb as well as natural sweetener. In this study, we performed quantification analysis of three major constituents including liquiritin, glycyrrhizin, and glycyrrhetinic acid in the 70% ethanol extracts of non-processed Glycyrrhizae Radix et Rhizoma and processed Glycyrrhizae Radix et Rhizoma using a high-performance liquid chromatography coupled with photodiode array detector. The analytical column for separation of the 3 constituents used a Gemini C18 column kept at $40^{\circ}C$ by the gradient elution of two mobile phase. The amounts of liquiritin, glycyrrhizin, and glycyrrhetinic acid in non-processed Glycyrrhizae Radix et Rhizoma were 2.57%, 3.52%, and not detected. After processing by roasting, the best roasting temperature and time of iquiritin, glycyrrhizin, and glycyrrhetinic acid were $160^{\circ}C$-15 min (2.46%), $160^{\circ}C$-15 min (3.67%), and $240^{\circ}C$-15 min (0.76%), respectively.

• 생약학회지
• /
• 제47권4호
• /
• pp.360-365
• /
• 2016

The aim of this study was to compare the amount of spinosin in the 70% ethanol extracts of non-processed Zizyphi Semem (ZS) and processed ZS by roasting using a high-performance liquid chromatography equipped with photodiode array detector. Separation of the spinosin was used $SunFire^{TM}$ $C_{18}$ analytical column ($5{\mu}m$, $4.6{\times}150mm$) using two mobile phase consisting of distilled water and acetonitrile, both with 1.0% (v/v) acetic acid. The flow rate was 1.0 mL/min and injection volume was $10{\mu}L$. Calibration curve of the spinosin was y = 22339.45x+483.99 in tested concentration range ($1.28-20.00{\mu}g/mL$) and correlation coefficient was 1.0000. In non-processed ZS sample, the amount of the spinosin was 0.94 m/g, while, the amount of the marker compound in processed ZS samples were 0.66-1.10 mg/g.