Method for the preparation of liposome encapsulated vincristine for therapeutic use

A method of preparing a pharmaceutically acceptable liquid composition comprising liposome-encapsulated vincristine which is free of substantial degradation products, the method comprising:

• (a) constituting in a single vial (i) a first solution comprising vincristine sulfate at a concentration of about 1 mg/ml to about 5 mg/ml, wherein the first solution has a pH of about 3.5 to about 5.5;
• and (ii) a second solution comprising sphingomyelin/cholesterol liposomes at a low pH;
• (b) raising the pH of the constituting solution in the single vial to a pH of about 7.0 to 7.5;
• (c) heating the single vial comprising the constituting solution in a dry heat block equilibrated at about 75° C. for at least about 13 to about 18 minutes, wherein said heat block comprises one or more bores about 1-5% larger than the average length or diameter of the single vial to produce a solution comprising constituted liposome encapsulated vincristine;
• and
• (d) equilibrating the constituted solution to room temperature.