Effect of controlled nucleation of ice crystals on the primary drying stage during lyophilization

Hidenori Kawasaki, Toshinori Shimanouchi, Kanako Takahashi, Yukitaka Kimura

Research output: Contribution to journalArticle

2 Citations (Scopus)


The freezing stage cannot be directly controlled, which leads to variation in product quality and low productivity during the lyophilization process. Our objective was to establish a robust design space for the primary drying stage using ice nucleation control based on the pressurization and depressurization technique. We evaluated the specific surface area (SSA), water content, scanning electron microscopy (SEM) images, and water vapor transfer resistance of the dried layer (Rp) of the products. The ice nucleation control resulted in a reduction of the SSA value and in an increase in water content. SEM observation suggested that the ice nucleation control enabled formation of large ice crystals, which was consistent with the reduction in the Rp value. As a result, the generation of collapsed cakes was inhibited, whereas 18% of the collapsed cakes were observed without ice nucleation control. Finally, this technique succeeded in determining a robust design space for the primary drying stage to produce uniform products of higher productivity. It was considered, from the present findings, that controlling the formation of large ice crystals impacted the product quality and productivity.

Original languageEnglish
Pages (from-to)1122-1130
Number of pages9
JournalChemical and Pharmaceutical Bulletin
Issue number12
Publication statusPublished - Jan 1 2018



  • Ice crystal
  • Lyophilization
  • Nucleation
  • Primary drying
  • Vial heat transfer coefficient

ASJC Scopus subject areas

  • Chemistry(all)
  • Drug Discovery

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