Publications by authors named "Kontoyannis C"

Any polymorphic conversion of an active pharmaceutical ingredient (API), even if partial, is likely to lead to changes in its efficiency and safety. Posaconazole, an antifungal drug, is detected as Form-S in the commercially available oral suspensions. However, a mixture of Form-S and the initial Form I is likely to coexist depending either on the manufacturing process of the suspensions and/or to the storage conditions of the suspension.

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Posaconazole is an API added as Form I for the production of oral suspensions, but it is found as Form-S in the final formulation. In this study, it was found that this polymorphic conversion, which may affect the bioavailability, is due to an interaction with water. However, the relatively poor wettability of posaconazole Form I renders the complete wetting of its particles and production of pure Form-S challenging.

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Article Synopsis
  • Raman spectroscopy is emerging as a viable alternative to traditional chromatographic techniques for detecting ethanol and other volatile substances in body fluids like blood and urine.
  • The study evaluates three different sample carriers for analyzing ethanol in human urine: a gold-coated carrier, a cuvette with a mirror, and a custom-designed microscope slide with cling film, finding that the last one is the most effective.
  • The custom microscope slide enabled quick and cost-effective identification of ethanol, achieving a limit of detection of 1.00 μL/mL while preventing ethanol evaporation.
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The assessment of active pharmaceutical ingredient (API) particle size and morphology is of great importance for the pharmaceutical industry since it is expected to significantly affect physicochemical properties. However, very few methods are published for the determination of API morphology and particle size of film-coated (FC) tablets. In the current study we provide a methodology for the measurement of API particle size and morphology which could be applied in several final products.

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Warfarin sodium is a low-dose pharmaceutical blood thinner that exists in two forms: the clathrate form and the amorphous form. In commercially available warfarin sodium oral suspension, the active pharmaceutical ingredient (API) is added in the amorphous state. This study investigates the apparent instability of the commercially available warfarin liquid oral formulation using Raman and IR spectroscopy, X-ray diffraction, differential scanning calorimetry, UV spectroscopy, and optical microscopy.

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Medical errors associated with IV preparation and administration procedures in a hospital workflow can even cost human lives due to the direct effect they have on patients. A large number of such incidents, which have been reported in bibliography up to date, indicate the urgent need for their prevention. This study aims at proposing an analytical methodology for identifying and quantifying IV drugs before their administration, which has the potential to be fully harmonized with clinical practices.

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FT-IR/ATR analytical technique is one of the most applicable techniques worldwide. It is closely associated with easy-to-use equipment, rapid analysis, and reliable results. This study reports the simultaneous qualitative and quantitative analysis of two active pharmaceutical ingredients (APIs), of a piperacillin and tazobactam formulation using a film formation method.

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Determination of the polymorphic form of an active pharmaceutical ingredient (API) in a suspension could be really challenging because of the water phase and the low concentration of the API in this formulation. Posaconazole is an antifungal drug available also as an oral suspension. The aim of this study was to develop a sample-preparation method for polymorphic identification of the dispersed API by increasing the concentration of the API but with no compromise of polymorph stability.

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The functional role(s) of plant calcium oxalate (CaOx) crystals are still poorly understood. Recently, it was shown that crystals function as dynamic carbon pools whose decomposition could provide CO to photosynthesis when stomata are closed (e.g.

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Electronic cigarettes are considered healthier alternatives to conventional cigarettes containing tobacco. They produce vapor through heating of the refill liquids (e-liquids) which consist of propylene glycol, vegetable glycerin, nicotine (in various concentrations), water and flavoring agents. Heavy metals may enter the refill liquid during the production, posing a risk for consumer's health due to their toxicity.

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Land plants face the perpetual dilemma of using atmospheric carbon dioxide for photosynthesis and losing water vapors, or saving water and reducing photosynthesis and thus growth. The reason behind this dilemma is that this simultaneous exchange of gases is accomplished through the same minute pores on leaf surfaces, called stomata. In a recent study we provided evidence that pigweed, an aggressive weed, attenuates this problem exploiting large crystals of calcium oxalate as dynamic carbon pools.

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Calcium oxalate crystals are widespread among animals and plants. In land plants, crystals often reach high amounts, up to 80% of dry biomass. They are formed within specific cells, and their accumulation constitutes a normal activity rather than a pathological symptom, as occurs in animals.

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Imbalances in lipid metabolism affect bone homeostasis, altering bone mass and quality. A link between bone mass and high-density lipoprotein (HDL) has been proposed. Indeed, it has been recently shown that absence of the HDL receptor scavenger receptor class B type I (SR-B1) causes dense bone mediated by increased adrenocorticotropic hormone (ACTH).

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A new methodology for simultaneous quantitative analysis of allantoin and glycolic acid in snail mucus and cosmetic creams was developed. HPLC separation was achieved a Synergi-Hydro RP column within 7min using isocratic elution with potassium phosphate (pH 2.7; 10mM) at a flow rate of 0.

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Numerous calibration models were developed and tested for the quantitative analysis of collagen and bioapatite in bone using Raman spectroscopy. The ν1 phosphate vibration at 960 cm(-1) was used as indicator of the content of bioapatite while for collagen three markers were used: the C-H2 band at 2940 cm(-1) , the amide I band at 1667 cm(-1) and the vibrations of proline and hydroxyproline at 855 and 878 cm(-1) , respectively. Also a calibration model based on the PLS algorithm was developed, too.

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In several bone deproteination protocols the chemical agent used for protein cleavage is hydrazine. The effect of hydrazine deproteination method on the crystal size and crystallinity of the bone mineral was studied. Bovine bones were subjected to this protocol and the crystal size and crystallinity of the remaining bone mineral were determined by X-ray Diffraction (XRD), by measuring the width at the half of the maximum intensity of the (002) reflection.

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Fourier Transform Infrared Spectroscopy (FT-IR) was used successfully for the simultaneous quantitative analysis of calcium carbonate phases (calcite, aragonite, vaterite) in ternary mixtures. From the FT-IR spectra of pure calcite, aragonite and vaterite powders with KBr, the absorptivities, alpha, of the absorption bands at 713 cm(-1) for calcite, 745 cm(-1) for vaterite, 713 and 700 cm(-1) for aragonite, were determined. In order to overcome the absorption band overlapping a set of equations based on Beer's law was developed.

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Differential Pulse Polarography (DPP) was used for the quantitative determination of the free and adsorbed (non-entrapped) chlorothiazide (CHT) in the presence of liposomes. It was found that CHT polarographic signal depends both on the concentration of multilamelar (MLV) liposomes, due to its adsorption on the liposomal surface, and on their size. Calibration plots of CHT concentration versus current density, at pH 7.

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Atorvastatin calcium (ATC) is the active pharmaceutical ingredient (API) of the best selling lipid-lowering formulation Lipitor. Twelve ATC crystal forms are known and several pharmaceutical companies are developing or have developed generic drug formulations based on different ATC polymorphs. The strong overlap of the X-ray diffraction patterns (XRD) of the polymorphs with the respective patterns of the excipients, the presence of small API quantities in the tablet and the similarity of the crystal phase VIII XRD pattern used in the tablet examined in this work to that of phases IV and IX made identification difficult.

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A simple, non-destructive, methodology based on FT-Raman spectroscopy was developed for the quantitative analysis of risperidone in commercially available film-coated tablets. A simple linear regression model was constructed based on standard tablets, prepared using the same manufacturing process as the commercially available. The tablets contained 0.

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Two different nondestructive spectroscopy methods based on near-infrared (NIR) and Fourier transform (FT) Raman spectroscopy were developed for the determination of ticlopidine-hydrochloride (TCL) in pharmaceutical formulations and the results were compared to those obtained by high-performance liquid chromatography (HPLC). An NIR assay was performed by reflectance over the 850-1700 nm region using a partial least squares (PLS) prediction model, while the absolute FT-Raman intensity of TCL's most intense vibration was used for constructing the calibration curve. For both methodologies the spectra were obtained from the as-received film-coated tablets of TCL.

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Raman spectroscopy was applied for the direct non-destructive analysis of amiodarone hydrochloride (ADH), the active ingredient of the liquid formulation Angoron((R)). The FT-Raman spectra were obtained through the un-broken as-received ampoules of Angoron((R)). Using the most intense vibration of the active pharmaceutical ingredient (API) at 1568cm(-1), a calibration model, based on solutions with known concentrations, was developed.

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Identification of the crystal phase of an active pharmaceutical ingredient (API) in a pharmaceutical tablet is of outmost importance since different polymorphs exhibit different physicochemical properties. Furthermore, some of the crystal phases are protected by patents. Identification of Risperidone polymorph A in film coated commercial tablets was attempted using IR spectroscopy, Raman spectroscopy and X-ray powder diffraction (XRPD).

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The capability of FT-Raman spectroscopy for the fast and non-destructive quantitative analysis of liquid formulations was tested and the results were compared to those obtained by HPLC. Diphenhydramine hydrochloride (DPH), the active ingredient of Benadryl, was determined in the presence of the numerous excipients of the elixir. A Raman calibration model was developed by measuring the peak intensities of different standard solutions of DPH vibration at 1003 cm(-1).

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Methodologies based on FT-Raman spectroscopy and HPLC were developed for monitoring the stability of lovastatin in the solid state in the presence of gallic acid, a natural antioxidant. A Raman calibration curve was constructed using the area of the strong but overlapping vibration mode of lovastatin at 1645 cm(-1) and of the gallic acid at 1595 cm(-1). Mixtures of the active ingredient with the antioxidant were heated in the presence of atmospheric air up to 120 degrees C.

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