Pharmaceuticals co-crystals of ciprofloxacin with sulfamethoxazole, nicotinamide and tartaric acid

Otro; IV Reunión Internacional de Ciencias Farmacéuticas (RICiFa); 2016

Co-crystals are formed by an Active Pharmaceutical Ingredient (API) and one or more coformers (CoF) joined in crystal lattice by noncovalent interactions. Dissolution of lipophilic APIs can be improved applying crystal engineering. The aim of this study was to design, prepare and characterize co-crystals consisting of antibacterials ciprofloxacin (CIP) with sulfamethoxazole (SMX) or substances considered safe for human use, nicotinamide (NIC) and tartaric acid (TART), in order to improve solubility and dissolution rate of APIs.The complexes were generated by vapor diffusion of acetic acid over equimolecular mixtures of CIP with SMX, NIC or TART in solution (pH 7.4). Same procedure was performed to starting components. The products obtained were analyzed by optic, polarized light, hot stage and Scanning Electron Microscopy, by TLC, melting point, DRIFT and Powder X Ray Diffraction (PXRD).Melting temperatures of the solids were different to the APIs. According to TLC, each co-crystal had two components. Crystals were anisotropic and presented fibrous habit, except CIP-TART, which was amorphous. Diffractograms of the new solids showed absence of characteristic signals and new ones appeared. DRIFT spectra of CIP-TART exhibited new signals at 1725 cm-1 (COOH), 1275 cm-1 (OH), 1110-1060 cm-1 (C-N) and 920 cm-1 (-OC-OH) and absence of the signal at 2700 cm-1 (NH2+) indicated that CIP and TART are neutral species in the complex and a interaction between OH and N would occur. In CIP-NIC the signal at 1400 cm-1 (C=O) are absent and a new signal at 970 cm-1 appeared indicating a probably interaction between COOH groups. Finally, CIP-SMX presented a similar spectrum of CIP.We could obtain two new molecular complexes originated from the interaction between CIP and TART or NIC. No interaction between CIP and SMX was observed. To confirm these conclusions, the preparation of single crystals is the subject of further studies.