Acusphere, Inc.

Mark J Keegan

Howard Bernstein

Donald E Chickering, Iii

Julie A Straub

Greg Randall

David H Altreuter

Paul Kopesky

Sridhar Narasimhan

Methods and apparatus are provided for making particles comprising: (a) spraying an emulsion, solution, or suspension, which comprises a solvent and a bulk material (e.g., a pharmaceutical agent), through an atomizer and into a primary drying chamber, having a drying gas flowing therethrough, to form droplets comprising the solvent and bulk material dispersed in the drying gas; (b) evaporating, in the primary drying chamber, at least a portion of the solvent into the drying gas to solidify the droplets and form particles dispersed in drying gas; and (c) flowing the particles and at least a portion of the drying gas through a jet mill to deagglomerate or grind the particles. By coupling spray drying with 'in-line' jet milling, a single step process is created from two separate unit operations, and an additional collection step is advantageously eliminated. The one-step, in-line process has further advantages in time and cost of processing.

Methods and apparatus for making particles using spray dryer and in-line jet mill

Improved spray drying apparati, and methods of use thereof, have been developed. The spray drying equipment includes a primary drying chamber and a secondary drying apparatus which includes tubing having a length sufficient to increase the contact time between the drying gas and the droplets/particles to dry the particles to the extent desired, at a drying rate and temperature which would be too low to provide adequate drying without the secondary drying apparatus. The secondary drying apparatus increases the drying efficiency of the spray dryer system without increasing the drying rate, while minimizing loss in yield. Te secondary drying apparatus can include multiple secondary apparati, which are independently controlled for temperature and/or have different dimensions (cross-sectional areas and/or lengths), to allow for optimization of drying conditions. For example, in one embodiment, the temperatures of the secondary appararati are set to gradually increase, or decrease, enabling the particles to be dried at multiple temperatures and drying conditions. In another embodiment, the apparati have different dimensions to alter the velocity at which the particles are dried, to accommodate changes in particle aggregation or other properties affecting product yield. A preferred application for the spray drying process and equipment is in the production of microparticles, between about 1 and 200 &mgr;m in diameter, which can be used to deliver therapeutic and diagnostic agents.

Spray drying apparatus and methods of use

Improved spray drying methods of have been developed. The spray drying method includes use of a primary drying chamber and a secondary drying apparatus which includes tubing having a length sufficient to increase the contact time between the drying gas and the droplets/particles to dry the particles to the extent desired, at a drying rate and temperature which would be too low to provide adequate drying without the secondary drying apparatus. The secondary drying apparatus increases the drying efficiency of the spray dryer system without increasing the drying rate, while minimizing loss in yield. The ratio of the length of tubing to the length of the primary drying chamber is at least 2:1. The tubing diameter is substantially smaller than the diameter of the primary drying chamber, such that the particles move at higher velocity through the tubing to minimize product losses. The ratio of the cross-sectional area of the primary drying chamber to the cross-sectional area of the tubing most preferably is about 16:1. The tubing preferably is in a compact coil design, which can more easily be transported and which has minimum space requirements, and may optionally include a jacket to control the temperature of the secondary drying process. A preferred application for the spray drying process and equipment is in the production of microparticles, between about 1 and 200 &mgr;m in diameter, which can be used to deliver therapeutic and diagnostic agents.

Spray drying method

Improved spray drying apparati, and methods of use thereof, have been developed. The spray drying equipment includes a primary drying chamber and a secondary drying apparatus which includes tubing having a length sufficient to increase the contact time between the drying gas and the droplets/particles to dry the particles to the extent desired, at a drying rate and temperature which would be too low to provide adequate drying without the secondary drying apparatus. The secondary drying apparatus increases the drying efficiency of the spray dryer system without increasing the drying rate, while minimizing loss in yield The ratio of the length of tubing to the length of the primary drying chamber is at least 2:1. The tubing diameter is substantially smaller than the diameter of the primary drying chamber, such that the particles move at higher velocity through the tubing to minimize product losses. The ratio of the cross-sectional area of the primary drying chamber to the cross-sectional area of the tubing most preferably is about 16:1. The tubing preferably is in a compact coil design, which can more easily be transported and which has minimum space requirements, and may optionally include a jacket to control the temperature of the secondary drying process. A preferred application for the spray drying process and equipment is in the production of polymeric microparticles, between about 1 and 200 &mgr;m in diameter, which can be used to deliver therapeutic and diagnostic agents.

Growing community of inventors

Andover, MA, United States of America

Mark J Keegan