* * * INSIGHT * * *

Partial Cake Meltback During Lyophilization

By

Thomas A. Jennings, Ph.D.

ABSTRACT: A cake defect that is often a source of frustration and consternation is the random occurrence of partial meltback in the resulting product.  Partial meltback is a process defect that generally appears as a hole or discoloration on the bottom of the cake that occurs randomly throughout a given batch of lyophilized product having cosmetically acceptable cakes. The detection of this defect requires viewing the bottom of the vial. If the inspection is manually performed, then the inspector may be required to pick up and examine the base of each vial. Since only a small percentage (<1%) of the vials may be affected, the defect represents not only a loss in product but a nuisance to detect and remove from the batch. For example,  a batch size of 50,000 vials may contain 500 or more defective cakes resulting from partial meltback.  In addition, companies can be at a loss to provide regulatory agencies with the rational for the presence of this pesky defect. The subject of partial meltback and its probable cause has already been touched on briefly in a previous issues of INSIGHT (see Vol. 1 No. 2 and Vol. 1 No. 3 ).This issue of INSIGHT will examine the subject of partial meltback in greater detail and discuss the various sources of such a defect and possible means for its elimination.

Volume 1 Number 5                                                                                         July 1998

3 Pages          2 References          No Figures

[How to obtain a complete copy this INSIGHT]  [Return to Phase Home Page]