Salt screening and characterization of ciprofloxacin

Torsemide Crystalline Salts with a Significant Spring-Parachute Effect

Torsemide is a long acting pyridine sulfonylurea diuretic. Torsemide hydrochloride is widely used now, there are only a few organic acid salts reported. Cocrystallization with organic acids is an effective way to improve its solubility. Here, we reported maleate and phthalate of torsemide, in which the organic acid lost a proton transferring to the pyridine of torsemide, and torsemide interacted with organic acid through N+ - H⋯O- hydrogen bond to form salts crystal. Surprisingly, maleate showed a clear "spring" pattern in apparent solubility, whereas phthalate had a "spring-parachute" effect. Both crystalline salts kept a higher solubility than torsemide without falling. The "spring-parachute" effect of crystalline salts promoted rapid dissolution of torsemide and kept a high concentration, thereby increasing its bioavailability.

Enhanced NSAIDs Solubility in Drug-Drug Formulations with Ciprofloxacin

Drug-drug salts are a kind of pharmaceutical multicomponent solid in which the two co-existing components are active pharmaceutical ingredients (APIs) in their ionized forms. This novel approach has attracted great interest in the pharmaceutical industry since it not only allows concomitant formulations but also has proved potential to improve the pharmacokinetics of the involved APIs. This is especially interesting for those APIs that have relevant dose-dependent secondary effects, such as non-steroidal anti-inflammatory drugs (NSAIDs). In this work, six multidrug salts involving six different NSAIDs and the antibiotic ciprofloxacin are reported. The novel solids were synthesized using mechanochemical methods and comprehensively characterized in the solid state. Moreover, solubility and stability studies, as well as bacterial inhibition assays, were performed. Our results suggest that our drug-drug formulations enhanced the solubility of NSAIDs without affecting the antibiotic efficacy.

Ciprofloxacin-Loaded Titanium Nanotubes Coated with Chitosan: A Promising Formulation with Sustained Release and Enhanced Antibacterial Properties

Due to their high entrapment efficiency, anodized titanium nanotubes (TiO2-NTs) are considered effective reservoirs for loading/releasing strong antibiotics whose systemic administration is associated with diverse and severe side-effects. In this study, TiO2-NTs were synthesized by anodic oxidation of titanium foils, and the effects of electrolyte percentage and viscosity on their dimensions were evaluated. It was found that as the water content increased from 15 to 30%, the wall thickness, length, and inner diameter of the NTs increase from 5.9 to 15.8 nm, 1.56 to 3.21 µm, and 59 to 84 nm, respectively. Ciprofloxacin, a highly potent antibiotic, was loaded into TiO2-NTs with a high encapsulation efficiency of 93%, followed by coating with different chitosan layers to achieve a sustained release profile. The prepared formulations were characterized by various techniques, such as scanning electron microscopy, differential scanning calorimetry, and contact measurement. In vitro release studies showed that the higher the chitosan layer count, the more sustained the release. Evaluation of antimicrobial activity of the formulation against two endodontic species from Peptostreptococcus and Fusobacterium revealed minimum inhibitory concentrations (MICs) of 1 µg/mL for the former and the latter. To summarize, this study demonstrated that TiO2-NTs are promising reservoirs for drug loading, and that the chitosan coating provides not only a sustained release profile, but also a synergistic antibacterial effect.

Benchmarking the Solubility Enhancement and Storage Stability of Amorphous Drug–Polyelectrolyte Nanoplex against Co-Amorphous Formulation of the Same Drug

Amorphization, typically in the form of amorphous solid dispersion (ASD), represents a well-established solubility enhancement strategy for poorly soluble drugs. Recently, two amorphous drug formulations, i.e., the amorphous drug–polyelectrolyte nanoparticle complex (nanoplex) and co-amorphous system, have emerged as promising alternatives to circumvent the issues faced by ASD (i.e., large dosage requirement, high hygroscopicity). In the present work, the nanoplex was benchmarked against the co-amorphous system in terms of the preparation efficiency, drug payload, thermal stability, dissolution rate, supersaturation generation, and accelerated storage stability. Weakly acidic curcumin (CUR) and weakly basic ciprofloxacin (CIP) were used as the model poorly soluble drugs. The CUR and CIP nanoplexes were prepared using chitosan and sodium dextran sulfate as the polyelectrolytes, respectively. The co-amorphous CUR and CIP were prepared using tannic acid and tryptophan as the co-formers, respectively. The benchmarking results showed that the amorphous drug nanoplex performed as well as, if not better than, the co-amorphous system depending on the drug in question and the aspects being compared. The present work successfully established the nanoplex as an equally viable amorphous drug formulation as the more widely studied co-amorphous system to potentially serve as an alternative to ASD.

Ternary nanoparticle complex of antibiotic, polyelectrolyte, and mucolytic enzyme as a potential antibiotic delivery system in bronchiectasis therapy

Antibiotic-polyelectrolyte nanoparticle complex (or nanoplex in short) has been recently demonstrated as a superior antibiotic delivery system to the native antibiotic in bronchiectasis therapy owed to its ability to overcome the lung's mucus barrier and generate high localized antibiotic exposure in the infected sites. The present work aimed to further improve the mucus permeability, hence the antibacterial efficacy of the nanoplex, by incorporating mucolytic enzyme papain (PAP) at the nanoplex formation step to produce PAP-decorated antibiotic-polyelectrolyte nanoplex exhibiting built-in mucolytic capability. Ciprofloxacin (CIP) and dextran sulfate (DXT) were used as the models for antibiotics and polyelectrolyte, respectively. The results showed that the PAP inclusion had minimal effects on the physical characteristics, preparation efficiency, and dissolution of the CIP-DXT nanoplex. The optimal CIP-(DXT-PAP) nanoplex exhibited size and zeta potential of approximately 200 nm and -50 mV with CIP and PAP payloads of 60% and 32% (w/w), respectively. The nanoplex was prepared at high efficiency with larger than 80% CIP and PAP utilization rates. The CIP-(DXT-PAP) nanoplex exhibited tenfold improvement in the mucus permeability compared to its CIP-DXT nanoplex counterpart, resulting in the former's superior bactericidal activity against clinical Pseudomonas aeruginosa biofilm in the presence of mucus barrier. A trade-off, nevertheless, existed between antibacterial efficacy and cytotoxicity towards human lung epithelium cells upon the incorporation of PAP above a certain concentration threshold. Therefore, the optimal dosing of the CIP-(DXT-PAP) nanoplex must be carefully determined.

Ciprofloxacin salts with benzoic acid derivatives: structural aspects, solid-state properties and solubility performance

In this work, three new pharmaceutical hydrated salts of ciprofloxacin with selected derivatives of benzoic acid were obtained and systematically investigated by several solid-state analytical techniques.

Solvates of acotiamide hydrochloride: characterization and phase transformation

Five novel crystals of acotiamide hydrochloride (AH) with solvates dimethyl formide (DMF), dimethyl sulfoxide (DMSO), ethyl acetate (EA) and water (W) [1AH-1W-1DMF, 1AH-1DMSO-I, 1AH-1DMSO-II, 1AH-1W-1DMSO and 2AH-2DMSO-1EA] were characterized using single-crystal X-ray diffraction, powder X-ray diffraction, thermal analysis and Fourier transform infrared spectroscopy. The five crystals can be divided into four distinct structural types based on analysis of their similarities; 1AH-1W-1DMF and 1AH-1W-1DMSO are isostructural. The benzene rings in 1AH-1DMSO-I, 1AH-1DMSO-II and 2AH-2DMSO-1EA can rotate 180°, and the intramolecular hydrogen bond changes from an OH...C=O bond to an NH...OH bond relative to what is seen in 1AH-1W-1DMF and 1AH-1W-1DMSO. Phase transformation experiments show that a humidity-induced phase transformation is closely tied to moisture content.

Stacking as a Key Property for Creating Nanoparticles with Tunable Shape: The Case of Squalenoyl-Doxorubicin

The development of elongated nanoparticles for drug delivery is of growing interest in recent years, due to longer blood circulation and improved efficacy compared to spherical counterparts. Squalenoyl-doxorubicin (SQ-Dox) conjugate was previously shown to form elongated nanoparticles with improved therapeutic efficacy and decreased toxicity compared to free doxorubicin. By using experimental and computational techniques, we demonstrate here that the specific physical properties of SQ-Dox, which include stacking and electrostatic interactions of doxorubicin as well as hydrophobic interactions of squalene, are involved in the formation of nanoassemblies with diverse elongated structures. We show that SQ-Dox bioconjugate concentration, ionic strength, and anion nature can be used to modulate the shape and stiffness of SQ-Dox nanoparticles. As those parameters are involved in nanoparticle behavior in biological media, these findings could bring interesting opportunities for drug delivery and serve as an example for the design of original nanodrugs with stacking properties tuned for particular clinical purposes.

Effects of Lysozyme on the Activity of Ionic of Fluoroquinolone Species

Fluoroquinolones (FQs) constitute an important class of biologically active broad-spectrum antibacterial drugs that are which are in contact with many biological fluids under different acidity conditions. We studied the reactivity of ciprofloxacin (Cpx) and levofloxacin (Lev) and their interaction with lysozyme (Lyz) at different pH values, using UV-visible absorption, fluorescence, infrared spectroscopies supported by DFT calculation and docking. In addition, by antimicrobial assays, the biological consequences of the interaction were evaluated. DFT calculation predicted that the FQ cationic species present at acid pH have lower stabilization energies, with an electric charge rearrangement because of their interactions with solvent molecules. NBO and frontier orbital calculations evidenced the role of two charged centers, NH₂⁺ and COO-, for interactions by electronic delocalization effects. Both FQs bind to Lyz via a static quenching with a higher interaction in neutral medium. The interaction induces a structural rearrangement in β-sheet content while in basic pH a protective effect against the denaturation of Lyz was inferred. The analysis of thermodynamic parameters and docking showed that hydrophobic, electrostatic forces and hydrogen bond are the responsible of Cpx-Lyz and Lev-Lyz associations. Antimicrobial assays evidenced an antagonist effect of Lyz in acid medium while in neutral medium the FQs' activities were not modified by Lyz.

Towards medicinal mechanochemistry: evolution of milling from pharmaceutical solid form screening to the synthesis of active pharmaceutical ingredients (APIs)

This overview highlights the emergent area of mechanochemical reactions for making active pharmaceutical ingredients (APIs), and covers the latest advances in the recently established area of mechanochemical screening and synthesis of pharmaceutical solid forms, specifically polymorphs, cocrystals, salts and salt cocrystals. We also provide an overview of the most recent developments in pharmaceutical uses of mechanochemistry, including real-time reaction monitoring, techniques for polymorph control and approaches for continuous manufacture using twin screw extrusion, and more. Most importantly, we show how the overlap of previously unrelated areas of mechanochemical screening for API solid forms, organic synthesis by milling, and mechanochemical screening for molecular recognition, enables the emergence of a new research discipline in which different aspects of pharmaceutical and medicinal chemistry are addressed through mechanochemistry rather than through conventional solution-based routes. The emergence of such medicinal mechanochemistry is likely to have a strong impact on future pharmaceutical and medicinal chemistry, as it offers not only access to materials and reactivity that are sometimes difficult or even impossible to access from solution, but can also provide a general answer to the demands of the pharmaceutical industry for cleaner, safer and efficient synthetic solutions.

Diversity of crystal structures and physicochemical properties of ciprofloxacin and norfloxacin salts with fumaric acid

The crystallization of norfloxacin and ciprofloxacin – antibacterial fluoroquinolone compounds – with fumaric acid resulted in the isolation of six distinct solid forms of the drugs with different stoichiometries and hydration levels.

Structural adaptations of octaheme nitrite reductases from haloalkaliphilic Thioalkalivibrio bacteria to alkaline pH and high salinity

Bacteria Tv. nitratireducens and Tv. paradoxus from soda lakes grow optimally in sodium carbonate/NaCl brines at pH range from 9.5 to 10 and salinity from 0.5 to 1.5 M Na⁺. Octaheme nitrite reductases (ONRs) from haloalkaliphilic bacteria of genus Thioalkalivibrio are stable and active in a wide range of pH (up to 11) and salinity (up to 1 M NaCl). To establish adaptation mechanisms of ONRs from haloalkaliphilic bacteria a comparative analysis of amino acid sequences and structures of ONRs from haloalkaliphilic bacteria and their homologues from non-halophilic neutrophilic bacteria was performed. The following adaptation strategies were observed: (1) strategies specific for halophilic and alkaliphilic proteins (an increase in the number of aspartate and glutamate residues and a decrease in the number of lysine residues on the protein surface), (2) strategies specific for halophilic proteins (an increase in the arginine content and a decrease in the number of hydrophobic residues on the solvent-accessible protein surface), (3) strategies specific for alkaliphilic proteins (an increase in the area of intersubunit hydrophobic contacts). Unique adaptation mechanism inherent in the ONRs from bacteria of genus Thioalkalivibrio was revealed (an increase in the core in the number of tryptophan and phenylalanine residues, and an increase in the number of small side chain residues, such as alanine and valine, in the core).