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Biomedical subjects

A M Guyot-Hermann

Publications and source records attributed to A M Guyot-Hermann.

At least 19 recordsLinked to original sources
PubMed1999

Ibuprofen agglomerates preparation by phase separation.

The compression ability and dissolution rate of ibuprofen are poor. There are many processes to optimize these properties through adapted formulations. However, it would be more satisfactory to obtain directly during the crystallization step crystalline particles that can be directly compressed and quickly dissolved. This was the aim of this work. Ibuprofen spherical agglomerates were obtained using a very simple method based on the difference of solubility of ibuprofen in ethanol and in water. By cooling down an ibuprofen-saturated solution in an ethanol/water 50/50 mixture from 60 degrees C to room temperature under stirring, a phase separation occurs. Ibuprofen crystallizes in separated water droplets. After separation by sieving and drying, spherical agglomerates were obtained. A study of the physical properties of ibuprofen agglomerates was carried out using electron scanning microscopy and X-ray powder diffraction. The compression ability was tested using an instrumented tablet machine, and the dissolution rate was measured using continuous flow cells. An improvement in compression and dissolution properties of the spherical agglomerates produced was observed. The process of crystallization in a separated dispersed phase could be envisaged each time a drug exhibits opposite solubilities in two miscible solvents.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

Compression behavior of orthorhombic paracetamol.

PURPOSE: Orthorhombic crystals of paracetamol exhibit good technological properties during compression. The purpose of this study was to investigate the compression behavior of this substance and to compare it to that of monoclinic paracetamol. From the crystal structure, it could be hypothesized that sliding planes are present in the orthorhombic form, and could be responsible for an increase in crystal plasticity. METHODS: Compression of pure orthorhombic or monoclinic paracetamol tablets was carried out on a fully instrumented single punch machine. Data was used to establish Heckel's profiles. Images of compressed crystals were obtained by scanning electron microscopy. RESULTS: Tabletability of the orthorhombic crystals was far better than that of the monoclinic ones, and capping was not observed even at high compression pressure. Compared to the monoclinic form, orthorhombic paracetamol exhibited greater fragmentation at low pressure, increased plastic deformation at higher pressure, and lower elastic recovery during decompression. Plastic behavior was confirmed by SEM - micrographs showing that crystals folded under pressure. A compactibility study showed that the nature of interparticle bonds was similar for both polymorphs, the number of bonds being greater for orthorhombic paracetamol. CONCLUSIONS: Unlike the monoclinic form, orthorhombic paracetamol is suitable for the direct compression process. The crystalline structure accounts for its better compression behavior, because of the presence of sliding planes.

Acetaminophen↗
PubMed1991

An attempt to use artificial membranes to investigate cellular membrane permeation--application to nitroglycerin and isosorbide dinitrate.

The pharmacodynamic efficiency of nitroglycerin (TNG) is 3 to 4 times higher than that of isosorbide dinitrate (ISDN). In a previous work the authors have shown that this difference is partially due to the transmembrane diffusion potential of the molecules. The aim of this present study is to confirm this hypothesis by using artificial solid lipid membranes and thus to validate the method which will be used to predict the transmembrane diffusion of drugs. Two types of artificial membranes, having nearly the same liposolvent properties as the biological membrane, are tested to investigate intracellular drug penetration. These artificial membranes are fitted on the Dibbern's three phases apparatus: the Resomat 2. The results are in accordance with the data obtained on erythrocyte membranes showing that both drugs have a good transmembrane diffusibility and also that TNG presents a quicker intracellular penetration than ISDN. These results contribute to validate this method, using artificial membranes, to predict the intracellular penetration of molecules.

Cell Membrane↗