• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2265-2268
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• 2009

Terahertz time domain spectroscopy (THz-TDS) is applied in transmission to identify the five forms of modifications of furosemide and one commercial product from 0.3 THz to 1.6 THz at room temperature. The different absorption spectra of the different forms are sensitive to crystal structures. Density function theory (DFT) calculation was used to understand the vibrational modes of furosemide in the THz region. X-ray powder diffractometry (XRPD) was applied to confirm the different forms of modifications. The results demonstrate that THz-TDS is a potential analytical technique in investigating polymorphic forms in the pharmaceutical fields.

• Journal of Pharmaceutical Investigation
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• v.28 no.2
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• pp.81-85
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• 1998

Three polymorphic modifications and two pseudopolymorphic modifications of cefotaxime sodium were obtained by crystallization from different organic solvents. The isolated crystal forms were characterized by UV spectrophotometry, DSC, TGA and X-ray crystallography. Crystal forms of cefotaxime sodium were also compared by dissolution rate. The dissolution rate of form 1 was the highest, followed by form 2, form 4, form 6, form 5 and form 3. Among these polymorphic modifications the dissolution rate of form 3 and form 5 was much slower than that of cefotaxime sodium on the market. All forms showed no change after 2-month storage test in the silica gel desiccator. But after the storage of 2-month at 95% relative humidity condition, all forms were deliquesced by hygroscopic property except form 1 that showed the highest dissolution rate. At 52% relative humidity condition, form 1, form 2 and form 6 had no evidence of phase transformation, but form 3, form 4 and form 5 were also deliquesced.

• Journal of Pharmaceutical Investigation
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• v.30 no.3
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• pp.201-205
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• 2000

Three new polymorphic modifications were prepared by recrystallization under various conditions and characterized by DSC and X-ray crystallography. In pH 4.0 buffer at $37{\pm}0.5^{\circ}C$, the polymorphic modifications showed significant differences in the dissolution rate. The dissolution rate of Mod. 4, amorphous form, was faster than that of marketed cefaclor (Mod. 1). When all modifications were stored at 52% RH, 95% RH and in silica gel desiccator, any polymorphic transformation was not observed.

• Korean Journal of Oriental Medicine
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• v.13 no.1 s.19
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• pp.147-152
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• 2007

As a result to amplifying 12 samples of 'Sok-dan' through an random amplified polymorphic DNA (RAPD) method using eighteen DEC and URP primers, distinct band forms enabling discrimination of Phlomus umbrosa and Dipsacus asperoides were observable in the UBC 320 primer, UBC 367 primer, UBC 385 primer, UBC 414 primer, UBC 423 primer, URP 3 primer, URP 5 primer and URP 9 primer. The polymorph result amplified with a random primer was evaluated through Gelcompar II, showing a result dividable into two groups. The divided groups were the dried sample group of Dipsacus asperoides and the group of Phlomis umbrosa. In order to recognize the distinction between Dipsaci Radix types, the genetic variation of 'Sok-dan' produced domestically and imported was evaluated through RAPD, and the potential to distinguish these in forms of dried medicine was identified, presenting a method to authentification of Phlomis umbrosa and Dispacus asperoides.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2007-2010
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• 2009

Donepezil hydrochloride is a reversible acetylcholinesterase inhibitor that is used in the treatment of Alzheimer’s disease to improve the cognitive performance. It shows different crystalline forms including hydrates. Therefore, it is very important to confirm the polymorphic forms in the formulations of pharmaceutical materials because polymorphs of the same drug often exhibit significant differences in solubility, bioavailability, processability and physical/chemical stability. In this paper, four different forms of donepezil hydrochloride were prepared and characterized using X-ray powder diffraction, Fourier transform infrared, and solid-state nuclear magnetic resonance (NMR) spectroscopy. This study showed that solid-state NMR spectroscopy is a powerful technique for obtaining structural information and the polymorphology of pharmaceutical solids.

• Archives of Pharmacal Research
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• v.7 no.1
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• pp.47-52
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• 1984

Four polymorphic forms (I, II, III and IV) of hydrochlorothiazide have been characterized on the basis of x-ray diffractometry and differential thermal analysis. Form I was obtained by crystallization from N, N-dimethylformamide and Form II was crystallized from hot methanol. Form III was precipitated from sodium hydroxide aqueous solution by treatment with hydrochloric acid and Form IV was crystallized from 50% methanol. The metastable form I was a most stable form among four polymorphs, which was stable more than ten months at room temperature. The thermodynamic parameters such as heat of solution, enthalpy, entropy, free energy difference and transition temperature were determined by the measurement of intrinsic dissolution rate. The transition temperature and the heat of transition between the metastable Form I an Form II were determined to be $299.15^{\circ}$K and 5.03 Kcal/mole, respectively and free energy difference ($\delta$ F) was 302. 13 cal/mole. Diuretic action of these four polymorphic forms was also evaluated by monitoring the difference in urinary excretion of sodium, potassium and magnesium in rats.

• Journal of Pharmaceutical Investigation
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• v.23 no.2
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• pp.81-87
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• 1993

Five crystalline forms of cimetidine, four anhydrous and a monohydrate, have been prepared, and their thermal behavriours have been studied by differential thermal analysis and thermo-gravimetry. The dissolution rates of the five forms were determined in distilled water at $37^{\circ}C$. The results showed a significant difference in the dissolution rate. Polymorphic transformation occurred spontaneously during storage at room condition and was accelerated by applied energy during formulation process-milling.

• Journal of Pharmaceutical Investigation
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• v.28 no.2
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• pp.115-119
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• 1998

Five polymorphic modifications of Cephradin were prepared by recrystallization from organic solvents. The isolated crystal forms were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and X-ray crystallography powder diffractometry. Modificaition 1 was the most stable form and decomposed at $201.3^{\circ}C$. Modification 3 and 4 were metastable. The dissolution of modification 3 and 4 was faster than that of marketed form.

• Journal of Pharmaceutical Investigation
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• v.27 no.3
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• pp.233-239
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• 1997

Glibenclamide is a second generation sulfonylurea that is orally active as a hypoglycemic drug. It exists as a crystalline powder which is sparingly soluble in water. It was investigated that the potential of glibenclamide to exhibit polymorphism. Three polymorphic modifications (form 1, form 2 and form 3) and three pseudopolymorphic modifications (form 4, form 5 and form 6) were obtained by crystallization from different organic solvents. The isolated crystal forms were characterized by differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and X-ray crystallography powder diffraction studies. Form 1 was the most stable and melt at $175.4^{\circ}C$. Form 2 was metastable and melt at $151.0^{\circ}C$. Form 3 was a new polymorphic modification because it was different from form 1 and form 2 in X-ray crystallography powder diffraction data. Form 4 was a 1 : 7(toluene : glibenclamide) toluene solvate; form 5 was a 1 : 5(toluene : glibenclamide) toluene solvate; form 6 was a 3 : 8(pentanol : glibenclamide) pentanol solvate. All forms were stable in 3-month storage under 0% or 100% humidity condition. The dissolution rate of form 4 was highest; those of form 2, form 3, form 1, form 5 and form 6 followed.

• YAKHAK HOEJI
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• v.41 no.3
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• pp.321-327
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• 1997

Investigation of polymorphism has become a requirement in the pharmaceutical industry because the physical properties and bioavailabilities of crystalline drugs depend on their polymorphic form. Five polymorphic modifications and one pseudopolymorphic modification of ecphalothin sodium were prepared by recrystallization, and characterized by UV spectrophotometer, DSC, TGA and X-ray crystallography. The solubilities of all modifications were examined by the disslution test. Form 2 and 1 showed higher solubilities than any other crystal forms. The modifications were also investigated for their stability after storage of 2 months at 100%, 76%, 52% and 0% humidity.