This paper presents an industrial scale process for extraction, purification, and isolation of epiisopiloturine (EPI) (2(3H)-Furanone,dihydro-3-(hydroxyphenylmethyl)-4-[(1-methyl-1H-imidazol-4-yl)methyl]-, [3S-[3a(R*),4b]]), which is an alkaloid from jaborandi leaves (Pilocarpus microphyllus Stapf). Additionally for the first time a set of structural and spectroscopic techniques were used to characterize this alkaloid. EPI has shown schistomicidal activity against adults and young forms, as well as the reduction of the egg laying adult worms and low toxicity to mammalian cells (in vitro). At first, the extraction of EPI was done with toluene and methylene chloride to obtain a solution that was alkalinized with ammonium carbonate. The remaining solution was treated in sequence by acidification, filtration and alkalinization. These industrial procedures are necessary in order to remove impurities and subsequent application of the high performance liquid chromatography (HPLC). The HPLC was employed also to remove other alkaloids, to obtain EPI purity higher than 98%. The viability of the method was confirmed through HPLC and electrospray mass spectrometry, that yielded a pseudo molecular ion of m/z equal to 287.1 Da. EPI structure was characterized by single crystal X-ray diffraction (XRD), 1H and 13C nuclear magnetic resonance (NMR) in deuterated methanol/chloroform solution, vibrational spectroscopy and mass coupled thermal analyses. EPI molecule presents a parallel alignment of the benzene and the methyl imidazol ring separated by an interplanar spacing of 3.758 Å indicating a π-π bond interaction. The imidazole alkaloid melts at 225°C and decomposes above 230°C under air. EPI structure was used in theoretical Density Functional Theory calculations, considering the single crystal XRD data in order to simulate the NMR, infrared and Raman spectra of the molecule, and performs the signals attribution.

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Mechanochemistry synthesis was applied to the supramolecular synthesis and green scale-up production of a 1:1 drug–drug cocrystal involving the antimetabolite prodrug 5-Fluorocytosine (5-FC) and the tuberculostatic drug Isoniazid (INH), namely, 5FC-INH. Crystalline material, also obtained by traditional slow evaporation methods, was analyzed by single-crystal X-ray diffraction (XRD). The crystal packing is stabilized by a classical N–H···N hydrogen-bond interaction between the amine moiety of 5-FC and the INH pyridine nitrogen. IR and Raman data provided spectroscopic evidence about the hydrogen atom positions, thereby confirming the neutral nature of the cocrystal. Furthermore, 5FC-INH codrug was also evaluated by a range of analytical techniques such as powder XRD and thermal (thermogravimetric analysis, differential scanning calorimetry, hot stage microscopy) analyses. A physical stability study was performed in high relative humidity conditions to verify possible 5-FC solid-state hydration and/or INH degradation. The equilibrium solubility of this codrug was compared to the anhydrous 5-FC and INH raw materials, in pH 1.2 buffer media, and it was found to be similar to that of 5-FC, a biopharmaceutics classification system class I drug. The results show that the cocrystal has superior phase stability properties against moisture when compared to the starting pharmaceutical ingredients, so it could be considered as a potential candidate for the treatment of concomitant fungal infections, tuberculosis, and cancer.

Ethambutol (ETB) is a chiral dibasic compound formulated and marketed as the (S,S)-ethambutol dihydrochloride, (S,S)-EDH, to treat tuberculosis. It is administered orally in a solid formulation composed of isoniazid, rifampicin, and pyrazinamide as a fixed-dose combination tablet. Because of its high hygroscopicity, (S,S)-EDH is known for catalyzing the degradation of isoniazid by rifampicin to yield isonicotinyl hydrazone. In order to avoid or even minimize these mutual drug–drug interactions, in this work we have focused on the development of less hygroscopic multicomponent solid forms of ETB. Four salts of this drug, namely, oxalate (ETBOXA), maleate, terephthalate, and trichloroacetate, were prepared via supramolecular synthesis by the slow evaporation method and characterized by X-ray diffraction (single crystal X-ray diffraction, powder X-ray diffraction), spectroscopic (Fourier transform-infrared), and thermal (thermogravimetric analysis, differential scanning calorimetry, hot stage microscopy) techniques. The hygroscopic nature of these salts, including (S,S)-EDH, were evaluated, and all of them were found to be hygroscopic, with the exception of ETBOXA.

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For active pharmaceutical ingredients (API) in the solid state, the occurrence of hydration/dehydration phase transitions may have implications upon the efficiency of the pharmaceutical product, once they are often accompanied by changes of physicochemical properties. Thus, it is important for pharmaceutical research and development to investigate these mechanisms based on the crystal structures of the API. In this work, beyond the structural characterization of a new salt of the antidepressant drug Paroxetine [an HBr hemihydrate, (PRX+Br–)·0.5H2O], by single crystal X-ray diffraction (SXRD), thermal analysis (DSC/TGA), and hot stage microscopy (HSM), we were able to perform a complete investigation toward the reversible hydration/dehydration solid phase transitions occurring for this salt. In addition, solubility measurements for the anhydrous and hemihydrate solid forms of the new salt are compared with those of its isostructural hydrochloride hemihydrate salt, (PRX+Cl–)·0.5H2O, for which hydration/dehydration processes are still not completely understood due to structure instability after dehydration.

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Supramolecular reaction of 5-FC with caffeine, p-aminobenzoic and caprylic acid gave rise to solid forms physically stable in humid environments.