PubMed · 6750310
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A Hilgert, G Horch. 1982-07-30. [Long-term experiences with an antihypertensive combination].. https://pubmed.ncbi.nlm.nih.gov/6750310/
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Different beta-cyclodextrins have been tested as chiral additives in the mobile phase for the chromatographic analysis of chlorthalidone enantiomers in a C18 LiChrospher (125 x 4 mm I.D.) column. The effect on enantioresolution of different parameters was studied: composition of the mobile phase (percentage of organic solvent, type of buffer and pH), mobile phase flow-rate, and type and concentration of beta-cyclodextrin. A 25:75 mixture of methanol and 0.1 M phosphate buffer, pH 4, containing 2% triethylamine (v/v), and 12.5 mM beta-cyclodextrin, at a flow-rate of 0.8 ml/min, was found to be the best option for the resolution of chlorthalidone enantiomers. Under such conditions, linear calibration curves were obtained in the 0.5-20-microg/ml interval using UV detection at 230 nm. The limit of detection for both isomers was 50 ng/ml. The utility of the described assay has been tested by analyzing chlorthalidone in different pharmaceutical preparations. Examples of application to biological samples are also given.
The solubility of chlorthalidone in 16 solvent systems was determined in the absence and presence of different amounts of beta-cyclodextrin (beta-CD). Chlorthalidone (CT) was shown to be more soluble in hydrophilic organic solvents, with the highest solubility in ethylacetate (EtOAc) saturated with water. The solubility of CT in water, butanol, octanol, and dichloromethane (DCM) was enhanced by the addition of beta-cyclodextrin. The enantioselective partitioning of CT between water and EtOAc, DCM, butan-1-ol, butan-2-ol, and octan-1-ol was determined in the presence of beta-CD at pH 5, 7, and 9. According to the results, both the solubility and partitioning properties of CT are affected by beta-CD in aqueous solution. It was also shown that the solubility of the individual enantiomers differs in the presence of beta-CD.
The photodegradation process of the phototoxic diuretic drug chlorthalidone was studied. The products of its photolysis under UV-B were isolated and identified. Chlorthalidone was found to be active when examined by photohemolysis on human erythrocytes, but not in the presence of the isolated photoproducts. Inhibition of the photohemolysis process induced by chlorthalidone on addition of reduced glutathione (GSH) or ascorbic acid suggests the involvement of radicals species. The inhibition with 1,4-diazabycyclo [2.2.2] octane (DABCO), sodium azide (NaN3) sowie 2,5-dimethylfuran proof the participation of singlet oxygen (1O2) in this process.