Abstract: Sterile, essentially crystalline cefazolin sodium for parenteral administration is prepared by a freeze-drying process wherein a C.sub.1 -C.sub.3 alcohol-water solution of cefazolin sodium containing about 10 percent by volume of the C.sub.1 -C.sub.3 alcohol is chilled slowly from room temperature to about -10.degree. C. over a 3-12 hour period and then rapidly cooled to -30.degree. to about -40.degree. C. and held for 1-2 hours before subjecting said frozen solution to a high vacuum and a moderate amount of heat to sublime the frozen solvent therefrom. The resulting powder dissolves rapidly in acceptable pharmaceutical diluents.

Abstract: Essentially crystalline cephalothin sodium for parenteral administration is prepared by a freeze-drying process wherein a (C.sub.1 -C.sub.3 alcohol or acetone)-water solution of cephalothin sodium containing from about 2 to about 10 percent of C.sub.1 -C.sub.3 alcohol or acetone by volume is chilled from room temperature to -20.degree. C., or below, preferably about -40.degree. C. over a 1-3 hour period and then warmed to from about -3.degree. C. to about -10.degree. C. and held for 3 hours or more, then cooled to -20.degree. C., or below, preferably about -40.degree. C., before subjecting said frozen solution to a high vacuum and a moderate amount of heat to sublime the frozen solvent therefrom. The resulting powder dissolves rapidly in acceptable pharmaceutical diluents. Alternatively, from about 2 to about 5 percent by weight of sodium bicarbonate, related to the amount of cephalothin sodium present, is added to the solution before freeze-drying.

Abstract: Sterile, essentially crystalline cephalosporins for parenteral administration are prepared by a freeze-drying process wherein, after rapidly cooling a solution of such cephalosporins to at least -15.degree. C. in no more than 3 hours, the frozen solution is held between about <0.degree. C. and about -10.degree. C. until the nucleation of the cephalosporin is substantially complete before subjecting said frozen solution to a high vacuum and a moderate amount of heat to sublime the water therefrom.

Abstract: The cephalosporin antibiotic, cefazolin sodium, is provided in the monohydrate crystalline form substantially free of other crystalline forms via addition of a concentrated solution of cefazolin acid in a water-miscible organic solvent such as DMAC to a sodium cation donor solution, e.g., sodium acetate in ethanol, wherein said sodium cation donor solution contains water in an amount sufficient to constitute 3-7 percent by volume of the mixed solutions.

Abstract: Sterile, essentially crystalline cephalosporins for parenteral administration are prepared by a freeze-drying process wherein, after rapidly cooling a solution of such cephalosporins to at least -15.degree. C. in no more than 3 hours, the frozen solution is held between about <0.degree. C. and about -10.degree. C. until the nucleation of the cephalosporin is substantially complete before subjecting said frozen solution to a high vacuum and a moderate amount of heat to sublime the water therefrom.