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Biomedical subjects

G Burgot

Publications and source records attributed to G Burgot.

9 recordsLinked to original sources
PubMed2006

Stability of oral liquid preparations of methylergometrine.

The stability of an oral ready to-use form of methylergometrine (0.05 mg/mL), which provides a convenient volume for administration (5 mL), was evaluated over a forty-seven-day period at different temperatures (5 degrees C and room temperature) without light in order to assign a shelf life. Methylergometrine was assayed by a stability-indicating HPLC method with diode array detection. The drug undergoes degradation under basic conditions and dry heat (50 degrees C). All the peaks of the degraded product were resolved from the standard drug with significantly different retention times. Statistical analysis proves that the method is reproducible and accurate for estimation of the intact drug. The pH of samples was monitored periodically for changes. Samples were also visually inspected for any colour change, precipitation or crystallization. At least, 96% of the initial methylergometrine concentration remained throughout the 47-day study period. Over the test period, no significant change was observed in the pH or colour of any of the samples. No degradation products were revealed. This study allowed an oral ready to use solution of methylergometrine (0.05 mg/ml) to be prepared, with a shelf life of more than one month (47 days) when stored at room temperature without light.

Chemistry, Pharmaceutical↗
PubMed2002

Protometric thermometric titrations of sparingly soluble compounds in water in the presence of n-octanol.

Thermometric titrimetry permits titration of acido-basic compounds in water in the presence of n-octanol. n-Octanol permits the solubilization of protolytes and moreover may also displace the equilibria of the titration reactions. Hydrochlorides of highly insoluble derivatives such as phenothiazine derivatives can be titrated with satisfactory accuracy and precision by sodium hydroxide despite their high pK(a) values. Likewise barbiturate salts can be titrated by hydrochloric acid. In the case of some salts, the methodology may permit the sequential titration of the ion and counter ion.

1-Octanol↗
PubMed2000

On the reduction of dithiolethiones and dithiolylium ions by NADPH and glutathione reductase.

Results of in vitro experiments carried out in water at 25 degrees C and at pH 7.56 proved that NADPH in the presence of yeast glutathione reductase did not react with 1,2-dithiole-3-thiones and 1,2-dithiole-3-ones. On the other hand, 3-methylthiodithiolylium ions did react in these conditions. The reaction was identified and methyl 3-mercaptopropenedithioate resulting from a two-electron reduction process was obtained. A kinetic scheme consisting in a biordered mechanism has been found (Km = 2.6 10(-5) mol x l(-1)). All these results raise the question of a possible in vivo methylation (or alkylation) of dithiolethiones occurring prior to any other reductive biochemical process they may undergo. They also raise the question of the very existence (or in any case the generalization) of a reductive metabolism of dithiolethiones.

Alkylation↗
PubMed2000

[Rigorous algorithms for calculating the exact concentrations and activity levels of all the different species during acid-base titrations in water].

The principles of two algorithms allowing the calculations of the concentration and activity levels of the different species during acid-base titrations in water are described. They simulate titrations at constant and variable ionic strengths respectively. They are designed so acid and base strengths, their concentrations and the titrant volume added can be chosen freely. The calculations are based on rigorous equations with a general scope. They are sufficiently compact to be processed on pocket calculators. The algorithms can easily simulate pH-metric, spectrophotometric, conductometric and calorimetric titrations, and hence allow determining concentrations and some physico-chemical constants related to the occurring chemical systems.

Acid-Base Equilibrium↗
PubMed1995

[Determination by thermometric titrimetry of the thermodynamic parameters of water/n-octanol transfer of several non-steroidal anti-inflammatory drugs].

The calorimetric determination by thermometric titrimetry of the water/n-octanol transfer enthalpies of some non steroidic anti-inflammatory compounds is described. By combining the values obtained with that of the free enthalpies of transfer issuing from the values of corresponding log P, it is possible to determinate the transfer entropies of the solutes. The whole results of the show that almost the transfers are both enthalpy and entropy driven. They demonstrate the occurrence of three different mechanisms of transfer.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

[Chemical potentials of solutes and quantitative structure-activity relationships: study in a series of barbiturates].

The part, displayed by the solvatation of the solute in 2 solvents with witch log P is determined, is studied by 2 indirect process. They consist to test some QSAR where the corresponding chemical potentials are effective but with different weighs than in log P. The results obtained with barbiturics confirm the importance of the couple water/n-octanol and show that taking account of two partitionning process can improve the significativity of the QSAR.

Barbiturates↗