Sitafloxacin Hydrate

Sitafloxacin Hydrate

Characterization of non-stoichiometric hydration and the dehydration behavior of sitafloxacin hydrate.[Pubmed:22223374]

Chem Pharm Bull (Tokyo). 2012;60(1):45-55.

Sitafloxacin (STFX) hydrate is a non-stoichiometric hydrate. The hydration state of STFX hydrate varies non-stoichiometrically depending on the relative humidity and temperature, though X-ray powder diffraction (XRPD) of STFX hydrate was not affected by storing at low and high relative humidities. The detailed properties of crystalline water of STFX hydrate were estimated in terms of hygroscopicity, thermal analysis combined with X-ray powder diffractometry, crystallography and density functional theory (DFT) calculation. STFX hydrate changed the water contents continuously and reversibly from an equivalent amount of dihydrate through that of sesquihydrate depending on the relative humidity at 25 degrees C. Thermal analysis and X-ray powder diffraction (XRPD) simultaneous measurement also revealed that STFX hydrate dehydrated into a hydrated state equivalent to monohydrate by heating up to 100 degrees C, whereas XRPD patterns were slightly affected. This indicated that the crystal structure of STFX hydrate was retained at the dehydration level of monohydrate. Single-crystal X-ray structural analysis showed that two STFX molecules and four water molecule sites were contained in an asymmetric unit. STFX molecules formed a channel structure where water molecules were included. At the partially dehydrated state, at least two of four water molecules were considered to be disordered in occupancy and/or coordinates. Insight into the crystal structure of STFX hydrate stored at low and high relative humidities and geometry of the hydrogen bond were helpful to estimate the origin of non-stoichiometric hydration of STFX hydrate.

Sitafloxacin hydrate for bacterial infections.[Pubmed:18806900]

Drugs Today (Barc). 2008 Jul;44(7):489-501.

Sitafloxacin Hydrate (DU-6859a, Gracevit), a new-generation, broad-spectrum oral fluoroquinolone that is very active against many Gram-positive, Gram-negative and anaerobic clinical isolates, including strains resistant to other fluoroquinolones, was recently approved in Japan for the treatment of respiratory and urinary tract infections. Sitafloxacin is active against methicillin-resistant staphylococci, Streptococcus pneumoniae and other streptococci with reduced susceptibility to levofloxacin and other quinolones and enterococci. Sitafloxacin has also demonstrated activity against clinical isolates of Klebsiella pneumoniae (including about 67% of strains producing extended-spectrum, beta-lactamases and resistant to ciprofloxacin), Enterobacter cloacae, Pseudomonas aeruginosa with some activity against quinolone-resistant strains and Acinetobacter baumannii. The in vitro activity against anaerobes is comparable to imipenem or metronidazole. In a published phase II randomized, open-label, multicenter study of patients hospitalized with pneumonia, sitafloxacin (400 mg once daily) was comparable to imipenem/cilastatin (500 mg three times a day). Results of the phase III trials of sitafloxacin are not available in English. The clinical safety profile of sitafloxacin has been characterized from 1,059 patients who participated in 10 clinical trials. The most common events with 50 or 100 mg twice daily were gastrointestinal disorders (17.2%), mostly diarrhea, and abnormal laboratory test results (16.2%), mostly liver enzyme elevations. For Japanese patients, sitafloxacin provides the broad-spectrum coverage promised by clinafloxacin and trovafloxacin and comparable to carbapenems. While it is currently limited by its potential for phototoxicity in Caucasians, phototoxicity is essentially irrelevant if sitafloxacin is used in hospitals and especially in intensive care units.