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Formulations with two or more active pharmaceutical ingredients (APIs) are a researched trend due to their convenient use compared with multiple medications. Moreover, drug-drug combinations may have a synergistic effect. Drotaverine hydrochloride (D-HCl) is commonly used for its antispasmodic action. The combination of a spasmolytic and an analgesic drug such as ibuprofen (Ibu) or ketoprofen (Ket) could become the answer for the treatment of localized pain. D-HCl:Ibu and D-HCl:Ket drug-drug interactions leading to the formation of eutectic compositions with increased bioavailability, obtained by mechanosynthesis, a green, solvent-free method was explored for the first time. The compatibility of Ibuprofen, Ketoprofen, and Drotaverine Hydrochloride was investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier-Transform Infrared spectroscopy (FTIR). Solid-liquid equilibrium (SLE) phase diagrams for the binary systems of active pharmaceutical ingredients were developed and the Tammann diagrams were designed to determine the eutectic compositions. The excess thermodynamic functions GE for the pre-, post-, and eutectic compositions were obtained using the computed activity coefficients data. Results show that drotaverine-based pharmaceutical forms for pain treatment may be obtained at 0.9 respectively 0.8 molar fractions of ibuprofen and ketoprofen which is advantageous because the maximum allowed daily dose of Ibu is about 6 times higher than those of D-HCl and Ket. The obtained eutectics may be a viable option for the treatment of pain associated with cancer therapy.

The dependences of the retention factor for some aromatic hydrocarbons at different column temperatures on the concentration of the organic modifier in mobile phase (acetonitrile) were studied under reversed-phase liquid chromatography, using two C18 chromatographic columns with the same constructive characteristics. From these dependences the extrapolated values of the retention factor for the aromatic hydrocarbons were calculated and then they were used for studying their temperature dependence by means of the van't Hoff plots. The graphs between the logarithm of the retention factor and the inverse value of absolute temperature of the column were characterized by good determination coefficients. The standard enthalpy variation associated to the transfer of studied hydrocarbons from the aqueous mobile phase to the stationary phase was calculated from these van't Hoff plots.

No abstract

Generally, the temperature influence on the retention of compounds. [...]