Method of preparing stable sterile crystalline cephalosporins for parenteral administration

Abstract From the Canadian patent

The present invention relates to a process for preparing sterile, essentially crystalline cephalothin sodium, cephaloridine betaine and cefazolin sodium for parenteral administration by a freeze-drying process wherein, after rapidly cooling a solution of such cephalosporins to at least -15°C. in no more than 3 hours the frozen, solution is held between <0°C. and -10°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. The instant invention provides an improved freeze-drying process wherein cephalosporins are prepared which are sterile essentially …