title: Low temperature properties of lyophilized solutions and their influence on lyophilization cycle design: pentamidine isethionate.
abstract: Pentamidine isethionate is a lyophilized antiprotozoal drug. Its solutions, when lyophilized, have been found to exhibit a range of properties that depend on its concentration and the manner in which it is allowed to freeze. These properties were examined by Differential Scanning Calorimetry (DSC), freeze-drying microscopy and X-ray powder diffraction. In DSC studies, the drug exhibited eutectic behavior with a eutectic temperature of -2.8 degrees C. Freeze-drying microscopic examination of a sample of solution after cooling at about 1 degrees C/min showed that the sample dried with retention up to -4 degrees C, where melting was observed. By using the appropriate drug concentration and manipulating the freezing stage, crystallization of the drug from solution could be induced during cooling to yield a crystalline end-product.
authors.affiliation: Product Development, Abbott Laboratories, North Chicago, Illinois.
authors.forename: N A
authors.initials: NA
authors.lastname: Williams
authors.forename: D L
authors.initials: DL
authors.lastname: Schwinke
mesh_terms: D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D005612:Freeze Drying; D005615:Freezing; D008853:Microscopy / Q000379:methods; D010419:Pentamidine / Q000737:chemistry*; D012995:Solubility; D012996:Solutions; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D012996:Solutions; D010419:Pentamidine