Moxifloxacin Micronization via Supercritical Antisolvent Precipitation

Supercritical antisolvent (SAS) precipitation is employed for micronization of moxifloxacin (MF), an antibiotic from the fluoroquinolone group, to develop new dosage forms of MF. With this technique, we produced, in a controllable fashion, MF particles with different sizes (0.6–8.0 μm) and morphologies (from polygonal sheets to elongated rectangular prisms). The infrared and circular dichroism spectroscopy data suggest that micronization of MF via SAS does not alter its chemical structure or cause racemization. We demonstrate that micronized forms of MF drug substance exhibit a 20 to 30% increase in the dissolution rate, as compared to the initial MF form, in a physiological medium (pH 7.4). The dissolution rate of the microparticles obtained via SAS micronization depends on their size, morphology, and degree of crystallinity. The various data obtained in this study will be used in formulating new dosage forms of MF for treatment of drug-resistant forms of tuberculoses.     

Chiral Heteroditopic Baskets Designed from Triazolated Calixarenes and Short Peptides

Cone calix[4]arenes and calix[6]arenes bearing two, three, and four short peptide units each having two chiral carbon atoms were prepared. The syntheses were performed by using an efficient modular approach that includes the Ugi preparation of the azido‐peptide followed by its reactions with the propargylated calixarenes under CuAAC (Cu^I‐catalyzed azide–alkyne cycloaddition) conditions. The three novel multitopic hosts were probed for their ability to bind metal ions by UV titration, and showed the highest complexation efficiency towards copper(II) and lead(II). These two cations possessed quite different complexation modes with copper(II) bound predominantly by multiple‐triazole sites, in contrast to lead(II), which is stabilized mainly by multiple interactions with amide groups of the peptide units. Circular dichroism data for the free chiral hosts, their equimolar mixtures with copper(II) perchlorate and lead(II) perchlorate, and for tertiary mixtures of all three compounds showed the formation of mono‐ and binuclear complexes, or a switching behavior, depending on the structure of the host and the addition order of the cations.     

Peculiarities of the excitation energy transfer in europium and terbium aromatic carboxylates and nitrate complexes with sulfoxides: Blocking effect

The influence of modification of the aromatic ligands on the excitation energy transfer to Ln³⁺ ions in europium and terbium carboxylates and nitrates was examined. The luminescence excitation spectra of three groups of the europium and terbium compounds: phenyl-, diphenyl-, triphenylacetates, phenoxyacetates and triphenylpropionates; 1- and 2-naphthylcarboxylates and 2-naphthoxyacetates; lanthanide nitrates with diarylsulfoxides (diphenyl- and dibenzylsulfoxides) and dialkylsulfoxides were investigated. The spectra of adducts of terbium phenylcarboxylates with 1,10-phenanthroline were also analyzed. The effect of the aliphatic bridges, which decouple the π–π- or p–π-conjugation in the ligand, on the energy transfer to Ln³⁺ ions (so-called blocking effect) was investigated. It was shown, that this decoupling leads to significant lowering of the energy of “ligand–metal ion” charge transfer states (LM CTS) in the europium carboxylate salts, just down to 27,800 cm⁻¹ in europium 2-naphthoxyacetate. As a consequence, the probability of the LM CTS participation in the excitation energy dissipation processes increases. A channel of the excitation energy dissipation in the region of 31,750 cm⁻¹ related to ligand electronic transitions was found in the europium and terbium nitrates with sulfoxides. It was demonstrated that a part of the energy absorbed by the aromatic ligand having aliphatic bridge can be emitted as the ligand fluorescence.     

Complexation of gallium(III) nitrate with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonic acid)

Russian Chemical Bulletin - Eight dissociation constants of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis (methylene phosphonic acid) (DOTMP, H8L) were determined for the first time by...     

PEG-Chitosan as a Perspective Stabilizing Agent for Liposomal Suspensions: The Influence of the Molecular Weight and Degree of PEGylation on the Physicochemical Properties of the Complex

The possibility of regulating the physicochemical properties (stability, size, and binding sites) of liposomal containers for drug delivery by selecting the molecular weight and degree of modification of PEG-chitosan is demonstrated. The effect of the regulation of the release of doxorubicin from liposomal containers depending on the properties of the polymer and pH is demonstrated.     

Effect of glycol chitosan on functional and structural properties of anionic liposomes

The possibility of using glycol chitosan to obtain stabilized liposome containers for doxorubicin delivery is demonstrated. The dissociation constants of the liposome complexes with glycol chitosan (3.4 × 10^–4 and 1.10 × 10^–5 depending on the aggregation state of the liposomes) are determined. It is shown that the formation of liposome complexes with glycol chitosan has a significant prolongation effect on the release of doxorubicin from the liposomes at pH 7.4.     

Phase and extraction equilibria in water-syntamide-5-ammonium sulfate and water-syntamide-5k-ammonium sulfate systems

Phase equilibria in ternary aqueous layering systems containing a commercial nonionogen surfactant (Surf.) syntamide-5 or syntamide-5k and an inorganic salting-out agent ammonium sulfate were studied. The potential application of the systems for liquid extraction of metal ions was assessed.