Powder formation by atmospheric spray-freeze drying

• US 20060130355A1
• Filed: 12/28/2005
• Published: 06/22/2006
• Est. Priority Date: 01/23/2004
• Status: Active Grant

• Current Assignee: Aerosol Therapeutics, LLC
• Original Assignee: Warren H. Finlay, Zhaolin Wang
• Inventors: Finlay, Warren H., Wang, Zhaolin
• Granted Patent: US 7,363,726 B2
• Time in Patent Office: Days
• US Class Current: 34/284
• CPC Class Codes: B01D 1/18 to obtain dry solids B01D1/24 takes precedence
• CPC Class Codes: B01J 2/04 in a gaseous medium if combined with suspending the material in a gas, e.g. fluidised beds B01J2/16
• CPC Class Codes: F26B 13/30 for applying suction F26B13/16 takes precedence
• CPC Class Codes: F26B 3/12 in the form of a spray , i.e. sprayed or dispersed emulsions or suspensions spray drying of solutions B01D1/18
• CPC Class Codes: F26B 5/06 the process involving freezing
• CPC Class Codes: F26B 5/065 the product to be freeze-dried being sprayed, dispersed or pulverised

Abstract

A method of manufacturing heat-sensitive pharmaceutical powder is disclosed. The original pharmaceutical substances are dissolved in a solution or suspended in a suspension, which is sprayed through an atomizing nozzle and frozen in a cold gas phase or liquid nitrogen atomized directly in the spray-freeze chamber or gas jacket at the same time (for cooling purposes). The particles are freeze-dried at roughly atmospheric pressure in a down-stream fluid flow with exit filter thereby to remove moisture entrapped on or inside the frozen particles. The system has applicability for forming other powders.

Claims

1. A method of creating a powder, comprising the steps of:

spraying a carrier liquid containing a powder forming ingredient to form a flow of liquid droplets;

entraining the flow of liquid droplets within a concurrent flow of coolant for sufficient time to freeze the liquid droplets into frozen particles; and

drying the frozen particles to form a dry powder.

2. The method of claim 1 in which the powder forming ingredient is suspended or dissolved in the carrier liquid.

4. The method of claim 1 in which the concurrent flow of coolant is sprayed from a ring nozzle.

5. The method of claim 1 in which the flow of liquid droplets is injected into a chamber and entrained by flowing coolant injected through porous walls of the chamber.

6. The method of claim 1 in which the frozen particles are collected on a filter.

7. The method of claim 6 in which the frozen particles are substantially dried after being collected on the filter.

8. The method of claim 1 in which the flow of coolant has a temperature within a first temperature range during freezing of the liquid particles and a temperature warmer than the first temperature range during drying of the frozen particles.

9. The method of claim 1 in which the carrier liquid contains more than one powder forming ingredient.

21. The method of claim 1 in which the coolant is a gas.

22. The method of claim 21 in which the coolant is a gas formed by vaporization of a cold liquid.

23. The method of claim 22 in which the cold liquid is liquid nitrogen.

24. The method of claim 5 in which the porous walls of the chamber comprise side walls, and the carrier liquid is sprayed from a first end of the chamber.

25. The method of claim 24 in which the frozen particles are collected on a filter at an end of the chamber opposed to the first end, and dried on the filter.

3. (canceled)

10-20. -20. (canceled)