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Claims for Patent: 4,882,452

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Claims for Patent: 4,882,452

Title: Process for the preparation of ifosfamide having improved properties
Abstract:Ifosfamide having improved properties is obtained by crystallization from a solvent mixture selected from the group consisting of (a) a mixture of diethyl ether and a C.sub.1 -C.sub.3 alkanol or (b) a mixture of diisopropyl ether and a C.sub.1 -C.sub.3 alkanol under specific controlled conditions.
Inventor(s): Engel; Jurgen (Alzenau, DE), Muller; Siegfried (Bad Homburg, DE), Laubner; Werner (Halle, DE)
Assignee: Asta Pharma Akteingesellschaft (Frankfurt am Main, DE)
Application Number:07/163,586
Patent Claims: 1. Needle-shaped prismatic crystalline ifosfamide characterized by the following properties:

(a) at least 70% of the crystals have a particle size between 150-550 .mu.m, the individual crystals have a ratio of length to width of 3.5:1 to 8:1, and

(b) the crystals have a maximum average relative standard deviation or the deviation of the individual values from the desired value at filling tests between 0.90% and 2% of 1.4%.

2. A process for the preparation of ifosfamide having improved properties, which comprises the steps of:

(a) forming a solution of ifosfamide in a solvent mixture selected from the group consisting of i. a mixture of diethyl ether and a C.sub.1 -C.sub.3 alkanol and ii. a mixture of diisopropyl ether and a C.sub.1 -C.sub.3 alkanol, the volume ratio of the C.sub.1 -C.sub.3 alkanol to the ether being 1:1 to 1:200, and the proportion of solvent mixture being 100 to 2000 ml per 100 g of ifosfamide.

(b) seeding the solution with pure ifosfamide at a temperature between -20.degree. to +25.degree. C. with stirring, the stirring being continued for several hours at the seeding temperature,

(c) optionally cooling the solution in step (b) evenly by stirring over a period of 8 to 48 hours to a temperature between 0.degree. C. to -5.degree. C., provided that the temperature is above 0.degree. C. when seeding takes place, and

(d) isolating and drying the resulting crystals.

3. A process according to claim 2 wherein the solvent mixture in step (a) is a mixture of diethyl ether and methanol.

4. A process according to claim 2 or claim 3 wherein the seeding in step (c) takes place at a temperature greater than 11.degree. C.

5. A process according to claim 2 or claim 3 wherein the seeding takes place at a temperature between 14.degree. and 20.degree. C.

6. A process according to claim 2 or claim 3 wherein cooling from the seeding temperature to the filtering temperature is carried out by using a cooling bath which is in thermal contact with the solution to obtain a controlled, even, and linear temperature reduction.

7. A pharmaceutical composition comprising a pharmaceutically effective amount of ifosfamide according to claim 1 and a pharmaceutical carrier or medium.

8. An aqueous solution of ifosfamide according to claim 1 having a pH of 5.5 to 6 containing 10% by weight of the crystals which is suitable for therapeutic use as an injection solution.
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