Patent ID: 7301024

Claim:
A method of making crystalline gatifloxacin form CX characterized by at least one of: (i) a powder x-ray diffraction pattern having reflections at about 6.5, 14.6, 17.4, and 19.4°±0.2° 2θ; and (ii) a differential scanning calorimetry thermogram having endothermic peaks at about 122° C. and about 137° C., comprising the steps of: a) combining an initial solution of gatifloxacin in DMSO with water at a temperature of about 55° C., b) cooling the combination to a temperature of about 0° C. at a cooling rate of about 10° per hour whereby a suspension is obtained, c) isolating the crystalline gatifloxacin form CX from the suspension, and d) washing the isolated crystalline gatifloxacin form CX with acetonitrile.