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  • Author or Editor: Piroska Szabó-Révész x
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Abstract  

Amorphization is nowadays a method that is frequently applied in the pharmaceutical industry. The primary aim of this study is to achieve the amorphization of clopidogrel hydrogen sulphate as an active pharmaceutical ingredient (API) with various solvents and to choose the most suitable one. A secondary aim was to determine the glass-transition temperature (T g) of this API and to classify it as a good or poor glass former. To investigate the amorphous form, differential scanning calorimetry, X-ray powder diffraction, and FT-IR analysis were applied. The melting point (T m) was 177.4 °C (450.6 K), and T g was determined to be 88.9 °C (362.1 K). The quotient T g/T m was 0.80, and this API was therefore classified as a good glass former.

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Abstract  

A study was made of the possibilities of gradually decreasing the concentration of the toxic organic solvent in the process of microsphere preparation. Ammonio methacrylate copolymer-based microspheres were prepared by spray drying or conventional solvent evaporation techniques, and compared. The formulations were designed by varying the preparation methods and the concentrations of four polar cosolvents as independent variables. DSC was used to study the relationship between the changes in the independent variables and three of the main thermal events of the microspheres. Raman spectroscopy was used to investigate and confirm the possible interactions between drug and copolymer. Appropriate choice of the independent variables led to the molecularly dispersed drug in the polymer matrix. It was demonstrated that only the nature of the preparation method caused significant variations in the structure and thermal behaviour of the microspheres.

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Abstract  

The aim of this work was to investigate the influence of different levels of microwave irradiation on the structure and particle size characteristics of α-lactose monohydrate. The structural study of the samples was carried out by XRD, the presence of lactose polymorphs in the test samples was determined by DSC and the particle size distribution was measured by laser diffraction. The samples subjected to microwave irradiation retained their original X-ray patterns. No significant differences in thermal transition characteristics and particle size were observed. Hence, neither the occurrence of crystalline-amorphous transition resulted by microwave irradiation nor the presence of lactose polymorphs in the test samples can be assumed. The unmodified properties can be attributed to the fact that the water of crystallization is very difficult to remove from the crystal structure and is not free to move during microwave treatment, which results in stability to microwaves. Our results allow the conclusion that microwave processing of α-lactose monohydrate has no influence on further pharmaceutical technological properties, which are related to the structure and the particle size distribution of this substance.

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Journal of Thermal Analysis and Calorimetry
Authors: Eszter Csizmazia, Mária Budai-Szűcs, István Erős, Zsolt Makai, Piroska Szabó-Révész, Gábor Varju, and Erzsébet Csányi

Abstract  

Our aim was to develop potential dermal drug delivery systems (DDSs) with a good and lasting moisturizing effect. Lyotropic liquid crystals (LLCs), gel-emulsions and hydrogels were investigated by means of thermogravimetry, which can give information about the structure of these preparations, and we could study the water binding mechanisms indirectly in them. We found that the preparations with a complex structure and strong water bonds hydrate the skin well and lastingly by in vivo tests. Since the thermoanalytical results correlate with the in vivo test results, this method could be suited for predicting the moisturizing effect of the vehicles and provide the possibility to select the potential semisolid DDSs for in vivo tests cost and time effectively.

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Abstract  

The purpose of this investigation was to further elucidate calorimetric properties of cartilage samples from femoral head necrosis and osteoarthritis from live surgeries. The natural course of this disease is one of steady progression with eventual collapse of the femoral head, followed by secondary osteoarthritis in the hip joint. All samples showed a clear denaturation peak on the calorimetric curve. Cartilage obtained from necrotic femoral head required the lowest amount of energy for decomposition. The use differential scanning calorimetry as part of thermal analysis was a reliable method for differentiating.

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Abstract  

The purpose of this study was to further characterize the altered metabolism spondylolisthesis that promotes disease progression. Degenerative human cartilage (intervertebral disc, facet joint and vertebral end-plate) was obtained during 15 posterior lumbar spine interbody fusion procedures performed at the University of Szeged. The thermal properties of samples were determined by differential scanning calorimetry (Mettler-Toledo DSC 821e). Greatest change in the enthalpy was observed in the intervertebral disc samples: −1600.78 J g−1. Denaturation caused by heating in the normal human hyaline cartilage needed −1493.31 J g−1 energy. Characterization of the altered metabolism that promotes disease progression should lead to future treatment options.

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Abstract  

The glenohumeral joint is not a classical mass bearing joint, the treatment of primary osteoarthritis is conservative. In all other cases, when the arthritis is associated with unbalance of the soft tissues, the treatment solution of this pathology is arthroplasty. The purpose of this study was to examine the altered metabolism in human degenerated cartilage of the shoulder joint. With the rise of temperature an endothermic reaction was observed in all cases. The use differential scanning calorimetry as part of thermal analysis was a reliable method for differentiating normal hyaline cartilage from degenerated samples.

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Abstract  

During recent years, knowledge of rheumatoid arthritis has increased, and management of the disease has improved. A limited number of papers have been published before on the subject of thermal analysis of degenerative cartilage but rheumatoid arthritis (RA) has not been studied previously. A new protocol had to be established before the investigation. The purpose of this study was to further characterize the altered metabolism in human RA cartilage that promotes disease progression. Previously, these methods have not been used for this purpose. The use of thermal analysis could be an effective method for controlling the relationship between biomarkers and disease progression.

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Journal of Thermal Analysis and Calorimetry
Authors: Mária Szűcs, Patrizia Vaghi, Giuseppina Sandri, M. Bonferoni, Carla Caramella, Piroska Szabó-Révész, and I. Erős

Abstract  

Polymeric emulsifiers provide exceptional stability to oil-in-water, water-in-oil or multiple emulsions by their steric stabilization. Pemulens as polymeric emulsifiers are able to stabilize o/w type emulsions because their short lipophilic part integrates into the oil droplets while their long hydrophilic part forms a micro gel around the droplet. In our present study the microstructure and integration of the polymeric emulsifier at the water-oil interface was investigated with thermogravimetric and microscopical methods. It was established that depending on the amount of both of the polymeric emulsifier and added coemulsifier the microstructure of the system changes.

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Abstract  

Sugar esters (SEs) have a wide range of hydrophilic-lipophilic balance (HLB) values (1–16) and hence can be applied as surfactants or as solubility or penetration enhancers. They can be used for hot melt technology and solvent method which are frequently applied techniques to preparation of solid dispersions. In this study drug-SE products were prepared by physical mixing, melt technology and solvent methods. The products were investigated by DSC, X-ray powder diffraction and dissolution tests. Diclofenac sodium (DS) as model drug and two SEs, P1670 (HLB=16) and S970 (HLB=9) were used for the preparation of the products. DSC curves revealed considerable melting range and enthalpy decreases for the DS-SE products. The dissolved drug molecules broke down the structures of the SEs but were not built into the crystalline phase of the carrier. The melt technology led to a solid dispersion while in the case of the solvent methods the DS was in molecularly dispersed form which resulted in faster dissolution. The drug release was influenced by the structures resulting from the various treatments, by the HLB and by the gel-forming behaviour of the SEs.

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