Hydrogen bonding in a non-steroidal anti-inflammatory drug--Naproxen

Gaining Insight into the Role of the Solvent during Spray Drying of Amorphous Solid Dispersions by Studying Evaporation Kinetics

Spray drying is one of the most commonly used manufacturing techniques for amorphous solid dispersions (ASDs). During spray drying, very fast solvent evaporation is enabled by the generation of small droplets and exposure of these droplets to a heated drying gas. This fast solvent evaporation leads to an increased viscosity that enables kinetic trapping of an active pharmaceutical ingredient (API) in a polymer matrix, which is favorable for the formulation of supersaturated, kinetically stabilized ASDs. In this work, the relation between the solvent evaporation rate and the kinetic stabilization of highly drug-loaded ASDs was investigated. Accordingly, thermal gravimetric analysis (TGA) was employed to study the evaporation kinetics of seven organic solvents and the influence of solutes, i.e., poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA), fenofibrate (FNB), and naproxen (NAP), on the evaporation behavior. At 10 °C below the boiling point of the respective solvent, methanol (MeOH) had the lowest evaporation rate and dichloromethane (DCM) had the highest. PVPVA decreased the evaporation rate for all solvents, yet this effect was more pronounced for the relatively faster evaporating solvents. The APIs had opposite effects on the evaporation process: FNB increased the evaporation rate, while NAP decreased it. The latter might indicate the presence of interactions between NAP and the solvent or NAP and PVPVA, which was further investigated using Fourier transform-InfraRed (FT-IR) spectroscopy. Based on these findings, spray drying process parameters were adapted to alter the evaporation rate. Increasing the evaporation rate of MeOH and DCM enabled the kinetic stabilization of higher drug loadings of FNB, while the opposite trend was observed for ASDs of NAP. Even when higher drug loadings could be kinetically stabilized by adapting the process parameters, the improvement was limited, demonstrating that the phase behavior of these ASDs of FNB and NAP immediately after preparation was predominantly determined by the API-polymer-solvent combination rather than the process parameters applied.

Dehydrodipeptide Hydrogelators Containing Naproxen N-Capped Tryptophan: Self-Assembly, Hydrogel Characterization, and Evaluation as Potential Drug Nanocarriers

In this work, we introduce dipeptides containing tryptophan N-capped with the nonsteroidal anti-inflammatory drug naproxen and C-terminal dehydroamino acids, dehydrophenylalanine (ΔPhe), dehydroaminobutyric acid (ΔAbu), and dehydroalanine (ΔAla) as efficacious protease resistant hydrogelators. Optimized conditions for gel formation are reported. Transmission electron microscopy experiments revealed that the hydrogels consist of networks of micro/nanosized fibers formed by peptide self-assembly. Fluorescence and circular dichroism spectroscopy indicate that the self-assembly process is driven by stacking interactions of the aromatic groups. The naphthalene groups of the naproxen moieties are highly organized in the fibers through chiral stacking. Rheological experiments demonstrated that the most hydrophobic peptide (containing C-terminal ΔPhe) formed more elastic gels at lower critical gelation concentrations. This gel revealed irreversible breakup, while the C-terminal ΔAbu and ΔAla gels, although less elastic, exhibited structural recovery and partial healing of the elastic properties. A potential antitumor thieno[3,2-b]pyridine derivative was incorporated (noncovalently) into the gel formed by the hydrogelator containing C-terminal ΔPhe residue. Fluorescence and Förster resonance energy transfer measurements indicate that the drug is located in a hydrophobic environment, near/associated with the peptide fibers, establishing this type of hydrogel as a good drug-nanocarrier candidate.

Chemiluminescence of the reaction system Ce(IV)-non-steroidal anti-inflammatory drugs containing europium(III) ions and its application to the determination of naproxen in pharmaceutical preparations and urine

The chemiluminescence (CL) of oxidation of non-steroidal anti-inflammatory drugs (NSAIDs) by Ce(IV) ions, was recorded in the presence and absence europium(III) ions, in solution of pH ~ 4 of solution. Kinetic curves and CL emission spectra of the all studied systems were discussed. CL of measurable intensity was observed in the Ce(IV)–NP–Eu(III) reaction system only in acidic solutions. The CL spectrum rcegistered for this system shows emission bands, typical of Eu(III) ions, with maximum at λ ~ 600 nm. The chemiluminescent method, based on Eu(III) emission in reaction system of NP-Ce(IV)–Eu(III) in acid solution was therefore used for the determination of naproxen in mixture of non-steroidal anti-inflammatory drugs.