Process for making sterile aripiprazole of desired mean particle size

Abstract

A process is provided for making sterile aripiprazole having an average particle size less than 100 microns but preferably greater than 25 microns employing an impinging jet crystallization procedure. The resulting bulk aripiprazole of desired particle size may be used to form a sterile freeze-dried aripiprazole formulation, which upon constitution with water and intramuscular injection releases aripiprazole over a period of at least about one week and up to about eight weeks.

1 . A process for preparing sterile crystalline aripiprazole of desired small particle size and narrow particle size distribution without milling, which comprises:
 (a) providing a jet stream of a solution of aripiprazole in an organic solvent;   (b) providing a jet stream of anti-solvent which is capable of initiating precipitation of aripiprazole from solution, wherein each of said aripiprazole-organic solvent stream and said anti-solvent stream is sterilized;   (c) causing the jet stream of solution of aripiprazole in solvent and the jet stream of anti-solvent to strike each other and impinge on one another to create high turbulence at their point of impact, each jet stream having sufficient linear velocity to achieve high intensity micromixing of each stream prior to nucleation, to produce a slurry of crystals of aripiprazole monohydrate; and   (d) recovering crystals of aripiprazole monohydrate of desired small particle size of average particle size of less than 100 microns but greater than 25 microns, and narrow particle size distribution, wherein at least 50% of said crystals have a particle size of less than 35 microns.   
     
     
         2 . The process as defined in  claim 1  further including the step of providing ultrasonic energy in the immediate vicinity of said impinging jet streams, so as to effect nucleation and the direct production of small crystals of aripiprazole. 
     
     
         3 . The process as defined in  claim 1  wherein the jet stream of the solution of aripiprazole in an organic solvent is heated at a desired elevated temperature and the jet stream of anti-solvent is at a desired temperature below the temperature of the other jet stream. 
     
     
         4 . The process as defined in  claim 1  wherein the organic solvent for the aripiprazole is ethanol, methanol, ethyl acetate, acetone, acetonitrile, acetic acid or isopropyl alcohol, or mixtures of one or more thereof, or mixtures with water. 
     
     
         5 . The process as defined in  claim 1  wherein the organic solvent for the aripiprazole is ethanol or a mixture of ethanol and water. 
     
     
         6 . The process as defined in  claim 1  wherein the anti-solvent is water. 
     
     
         7 . The process as defined in  claim 1  wherein the volumetric ratio of solution of aripiprazole in organic solvent to anti-solvent is within the range from about 0.5:1 to about 1.5:1. 
     
     
         8 . The process as defined in  claim 1  wherein the aripiprazole-solvent stream and the anti-solvent stream are in about a 1:1 volume ratio. 
     
     
         9 . The process as defined in  claim 1  wherein the organic solvent comprises ethanol and the solution of aripiprazole in ethanol is heated at a temperature within the range from about 70 to about 85° C. 
     
     
         10 . The process as defined in  claim 1  wherein the anti-solvent is water at a temperature within the range from about 2 to about 40° C. 
     
     
         11 . The process as defined in  claim 1  wherein the jet stream of a solution of aripiprazole in organic solvent and the jet stream of anti-solvent impinge each other at a flow rate of each which is the same or different but is within the range from about 0.2 to about 0.3 kg/min where jet nozzles of 0.02 inch internal diameter are employed. 
     
     
         12 . A process for preparing sterile aripiprazole of desired small particle size and narrow size distribution without milling, which comprises:
 (a) providing a jet stream of a solution of aripiprazole in ethanol/water heated at a temperature within the range from about 70 to about 85° C., wherein said stream is also sterilized;   (b) providing a jet stream of deionized water which is at a temperature within the range from about 2 to about 40° C., wherein said stream is also sterilized;   (c) causing the jet stream of solution of aripiprazole in ethanol and the jet stream of water each at a flow rate within the range from about 0.2 to about 0.3 kg/min, where jet nozzles of 0.02 inch internal diameter are employed, to impinge on one another to create high turbulence at their point of impact to achieve high intensity micromixing of each stream prior to nucleation, to form a slurry of crystals of aripiprazole monohydrate; and   (d) recovering crystals of aripiprazole monohydrate having an average particle size about 95% less than 100 microns, but greater than 25 microns.   
     
     
         13 . The process as defined in  claim 12  further including the step of providing ultrasonic energy in the immediate vicinity of said impinging jet streams, so as to effect nucleation and the direct production of small crystals of aripiprazole. 
     
     
         14 . The process as defined in  claim 12  wherein the aripiprazole has a low pyrogen content and is the anhydrous form of aripiprazole or the monohydrate form of aripiprazole. 
     
     
         15 . The process as defined in  claim 12  wherein the aripiprazole-ethanol solution contains from about 0.10 to about 0.1 kg/L aripiprazole. 
     
     
         16 . The process as defined in  claim 12  wherein the stream of aripiprazole in ethanol and the stream of deionized water flow in opposite directions and form a plane when they impinge one another, and strike each other to cause rapid homogeneous mixing and supersaturation due to high turbulence and high intensity of micromixing upon impact, which initiates rapid nucleation. 
     
     
         17 . The process as defined in  claim 12  wherein average crystal size decreases with increasing concentration of aripiprazole in ethanol and supersaturation and decreasing temperature of the anti-solvent. 
     
     
         18 . The process as defined in  claim 12  wherein the aripiprazole-ethanol stream and the water stream are in about a 1:1 volume ratio with each other.