1,721,098 research outputs found
Automatic control of a freeze-drying process: Detection of the end point of primary drying
No full textIn freeze-drying, the detection of the end of primary drying is a crucial aspect for both the process economics and product quality. Furthermore, the extreme process conditions (low temperature, high vacuum, and sterility) require monitoring devices with a high degree of assurance. In this paper, the most promising methodologies for the detection of the end point of primary drying were investigated and compared. These devices include thermocouples, comparative pressure measurement, condenser pressure, controlled leakage, vacuum shut-off valve, microbalance, mass spectrometers, moisture sensors, and pressure rise test. Furthermore, a multi-scale model of the process was used to describe the process dynamics during the last part of drying, showing that the time difference between the onset and offset points depends on the batch heterogeneity, as well as process conditions and batch size. Ultimately, an automatic stop criterion, named EPD, has been designed and experimentally tested in a wide range of process conditions, batch size, vial size, and drug products. In particular, the experimental validation involved some of the most used excipients as model products, i.e., mannitol, dextran, lactose, and sucrose. In all the runs, the EPD drying times reasonably agreed with the comparative pressure measurement, which was the most reliable way to detect the end of primary drying. Thus, EPD can effectively be used to optimize primary drying without risking the product collapse because of a premature increase in shelf temperature for secondary drying
Continuous manufacturing of lyophilized products: Why and how to make it happen
Full text linkThis paper deals with the problem of continuous lyophilization of pharmaceutical products, focusing on those concepts that are of greatest interest and most likely to be successful once applied in industrial practice. Also, it discusses all those factors that slow down the transition from batch to continuous in the pharmaceutical industry, and what actions may accelerate this transformation
The ice-water interface and protein stability: a review
Full text linkThe ice-water interface is commonly encountered in our life, and comes into play in a wide number of natural phenomena. Here, attention will be focused on its effects on protein stability, with specific reference to the case of pharmaceutical proteins. This field represents a fascinating, and not yet fully understood, subject of investigation. Some background information on the ice-water phase diagram, as well as to the mechanisms of nucleation and crystal growth, will be provided. We will eventually discuss the effect of ice on protein activity, reviewing the mechanisms of ice-induced denaturation that have been proposed so far and discussing the strategies that may help prevent, or minimize, undesired loss of therapeutic activity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
