PubMed · 13310843
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G CAVINA, E CINGOLANI. 1955. [Some hydroxyformylbenzoic acids].. https://pubmed.ncbi.nlm.nih.gov/13310843/
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The present study investigated the effect of water-soluble 4-sulphonato-calix[n]arenes, cyclodextrins, and combinations of these macromolecules on the aqueous solubility of a poorly water-soluble drug, niclosamide. Complexation between the macromolecules and niclosamide was confirmed by thermal analysis and phase solubility studies in a pH 7.0 Mcllvaine buffer kept at 30 degrees C. Results show that the increase in solubility ranked as follows: 4-sulphonato-calix[6]arene + hydroxypropyl-beta-cyclodextrin (HP-beta-CD) > 4-sulphonato-calix[6]arene + beta-cyclodextrin > 4-sulphonato-calix[6]arene + gamma-cyclodextrin = HP-beta-CD > 4-sulphonato-calix[6]arene > 4-sulphonato-calix[8]arene = 4-sulphonato-calix[4]arene > beta-cyclodextrin . Type B phase solubility profiles were observed, indicating a decrease in solubility at concentrations > 0.004 to 0.005 mol/L of the 4-sulphonato-calix[n]arenes or combinations of 4-sulphonato-calix[6]arene and the cyclodextrins. However, below this concentration, the greatest increase in the aqueous solubility niclosamide was observed when 4-sulphonato-calix[6]arene and HP-beta-CD were combined. This increase in solubility was additive.
Accumulation of o-chlorophenol (CP), 2,4-dichlorophenol (DCP), and atrazine (ATR), as single and mixed contaminants, from hydroponic solutions into roots and shoots of rice seedlings was studied following 48-h exposure of the plant roots. As single contaminants at low levels, the observed bioconcentration factors (BCFs) of CP and DCP with roots approximated the equilibrium values according to the partition-limited model. The BCF of atrazine with roots was about half the partition limit for unknown reasons. The BCFs of CP and ATR with shoots also approximated the partition limits, while the BCF for more lipophilic DCP with shoots was about half the estimated limit, due to insufficient water transport into plants for DCP. As mixed contaminants at low levels, the BCFs with both roots and shoots were comparable with those for the single contaminants; at high levels, the BCFs generally decreased because of the enhanced mixed-contaminant phytotoxicity, as manifested by the greatly reduced plant transpiration rate.
Mebendazole is a common benzimidazole anthelmintic that is water insoluble. It is reported to exist in three different polymorphic forms in the solid state, i.e. polymorph A, B and C. Form C is the pharmaceutically preferred form because of its increased aqueous solubility. This paper deals with the use of variable-temperature X-ray powder analysis (VTXRPD) to study the transformation of Form C. Results showed that Form C was stable and transformed to the more stable polymorph A at high temperature (>180 degrees C). This transformation is a first-order process with activation energy of 238 +/- 16 kJ/mole. Further studies showed that compression did not cause any significant changes in the crystal structure of polymorph C.