A Drug-Drug Salt Hydrate of Norfloxacin and Sulfathiazole: Enhancement of in Vitro Biological Properties via Improved Physicochemical Properties.

A new multicomponent solid consisting of an antibacterial (norfloxacin) and an antimicrobial (sulfathiazole) was made and characterized with single crystal X-ray diffraction, PXRD, FTIR, and DSC. The title salt shows enhanced solubility in different pH buffers and improved diffusion as well as release and inhibition of bacterial and fungal species relative to the parent drugs. The enhanced in vitro biological properties of the drug-drug salt hydrate may be attributed to the higher extent of its supersaturation with respect to the individual components, which leads to higher diffusion rates.

New multi-component solid forms of anti-cancer drug Erlotinib: role of auxiliary interactions in determining a preferred conformation.

Erlotinib is a BCS (biopharmaceutical classification system) class II drug used for the treatment of non-small cell lung cancer. There is an urgent need to obtain new solid forms of higher solubility to improve the bioavailability of the API (active pharmaceutical ingredient). In this context, cocrystals with urea, succinic acid, and glutaric acid and salts with maleic acid, adipic acid, and saccharin were prepared via wet granulation and solution crystallizations. Crystal structures of the free base (Z' = 2), cocrystals of erlotinib-urea (1:1), erlotinib-succinic acid monohydrate (1:1:1), erlotinib-glutaric acid monohydrate (1:1:1) and salts of erlotinib-adipic acid adipate (1:0.5:0.5) are determined and their hydrogen-bonding patterns are analyzed. Self recognition via the (amine) N-H...N (pyridine) hydrogen bond between the API molecules is replaced by several heterosynthons such as acid-pyridine, amide-pyridine and carboxylate-pyridinium in the new binary systems. Auxiliary interactions play an important role in determining the conformation of the API in the crystal. FT-IR spectroscopy is used to distinguish between the salts and cocrystals in the new multi-component systems. The new solid forms are characterized by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) to confirm their unique phase identity.