The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 
 
 
 
 

Crystallization of cephalothin sodium during lyophilization from tert-butyl alcohol-water cosolvent system.

PURPOSE: Because cephalothin sodium (I) does not crystallize readily when freeze-dried from aqueous solutions, organic cosolvents were used to increase the crystallinity of lyophilized I. METHODS: Compound I was lyophilized from water-organic cosolvent (5% w/w) systems of each ethanol, ispropanol, and tert-butyl alcohol (TBA). RESULTS: When frozen solutions of I (10% w/w) in each of these cosolvent systems was characterized by DSC, the presence of cosolvent in the freeze-concentrate was evident. Moreover, the presence of the cosolvent accelerated the solute crystallization. This observation was based on the XRD of these systems during the various stages of freeze-drying. High initial solute concentration and annealing of frozen solutions facilitated the formation of a highly crystalline lyophile. The accelerated crystallization is attributed to supersaturation in cosolvent systems, facilitating nucleation during freezing with subsequent growth during annealing. Lyophiles obtained from water-isopropanol and water-ethanol systems collapsed, while the use of TBA as a cosolvent yielded a friable and pharmaceutically elegant cake, containing fine needle-shaped crystals of I. Gas chromatography revealed a residual TBA concentration of approximately 0.001% w/w in the crystalline lyophiles. In general, residual cosolvent levels were higher in lyophiles with lower crystallinity. CONCLUSIONS: TBA-water was found to be a suitable freeze-drying medium to promote crystallization of I and yielded a lyophile with desirable product characteristics.[1]

References

 
WikiGenes - Universities