* * * INSIGHT * * *

The Pressure of Secondary Drying

By

Thomas A. Jennings, Ph.D.

On April 25-26, 2001, I attended a conference titled Lyophilization for Pharmaceutical and Biotechnology Industries that was held in Philadelphia, Pennsylvania. At various times during the conference I found myself faced with a dilemma. It is the feeling that one gets when they listen to more than one performer sing a familiar tune off key. To those who are not familiar with the song, the singers performed quite well but for me I found myself in quite a quandary. After finishing their presentation and hearing the applause of the audience and they ask for any questions, how does one standup and tell the speakers that, at times, they were singing off key. It would not be a question and only a source of embarrassment for the speakers. So rather than spoil the friendly mood of the conference, one remains silent. But after the conference, the off key portion of the presentations continued to haunt me so I have elected to speak out now so that I will not embarrass any one of whom some I know quite well.

The part of their presentations that bothered me so much was their implying that lowering the pressure in the chamber during the secondary drying process would not result in a reduction in the moisture content of the final product. They offered no supporting theoretical basis or data to justify their matter of fact statements and I was sure that many novices,  of which I am one, may have accepted the statement without question. Let me  share with you my understanding of the effect that pressure will have on the secondary drying process.

Volume 4 No. 6                                                                                          June 2001

4 Pages          2  References          1 Figure

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