Milling system meets AZ's demands: a new nitrogen-purged milling system for delumping an active pharmaceutical ingredient prior to packaging was supplied to AstraZeneca by Hosokawa Micron--with the companies working very closely to ensure that all the special processing requirements were met.

Designed in conjunction with AstraZeneca engineers to provide integrated and additional safety features and superior cleaning procedures, a new nitrogen-purged milling system demonstrates best operating practices for handling potentially explosive fine powder APIs. The milling process has been introduced to the production line to deliver a homogenous, free-flowing, lump-free product of consistent particle size at AZ's Macclesfield (UK) plant. To facilitate the homogenization of this API, the system has been designed to incorporate a classic homogenization mill, the Bepex Bexmill. With its low energy, gentle action, the Bexmill is ideally suited to handling sensitive products, such as pharmaceuticals, where a significant temperature rise would be detrimental. It has a single, vertical rotor that rotates close to a conical screen mesh and, by careful selection of screen mesh size and adjustment of the rotor speed, lumpy materials can be rendered free flowing and of a consistent particle size. Airflow through the unit is minimal and the product temperature rise is insignificant, ensuring very gentle size reduction with minimum fines.

The AstraZeneca material is transferred from a pressure filter dryer into a receiving vessel and then metered into the easy-to-clean Bexmill via a rotary valve. The Bexmill is a slow speed comminution device that is very effective in delumping without product damage. After milling, the product falls into a receiving hopper and is then transferred to the packaging drums using an inclined screw conveyor. The whole system is operated under a positive pressure of nitrogen and has an integrated self-leak test facility. The system is pressurized to 0.1 bar and, until the leak integrity test has proved that no leak has been detected and a green light been activated, the system cannot start. Once the system has passed the leak test, then the milling sequence can commence. Designed to be easily cleaned by hand, the whole system can be readily stripped down before a final sterilization, with compressed air and peracetic acid at 0.1 bar takes place.

[ILLUSTRATION OMITTED]

John Sherwood, Associate Principal Scientist, Product Development PR&D, at AstraZeneca Macclesfield, said: "We are always looking at the opportunities for product, process and environmental improvement, with our personnel being a key factor in the determination of technology--both in terms of technical input and health and safety. AstraZeneca has total commitment to meet or exceed the legal requirements and international agreements, in respect of Heath and Safety and Environment, and to provide a safe and healthy work environment for all our employees."

More information

Hosokawa Micron

T. [phone]

F. [phone]

E. [e-mail]

www.hosokawa.co.uk