Microbial retention characteristics of sterilizing-grade membrane filters with alginate substituted for oil-based products

So Hee Lee, Chan Wha Kim

Research output: Contribution to journalArticle

2 Citations (Scopus)


For oil-based products, FDA recommends substitution of the oil with a compound which has similar viscosity and physical characteristics. In this study, a substitute for oil-based products was screened by measuring the viscosity and filterability, and examined for the presence of cell clumps in the various test fluids using an optical microscopy. The viscosity of the test fluids measured in the range of about 60-75 cP. Brevundimonas diminuta (formerly Pseudomonas diminuta), a standard challenge test organism for validation of 0.2 μm rated membrane filters, formed clumps in oils (corn, olive, sesame, and soybean) and polyethylene glycol (PEG, Molecular Weight (MW) = 400 and 1,000). During the viability test, cells suspended in 80% glycerol showed a ten-fold mortality rate after an exposure for 6 hours, but there was no significant change in viability in alginate (low, medium, and high viscosity) for 24 hours. These results suggested that alginate is better suited as a substitute for oil-based products than 80% glycerol. Since high viscosity fluids take longer to filter, the glycerol mortality rate would influence the challenge test negatively. A scaled-down filtration system has been developed for the described trials, and the bacterial challenge and bubble point tests have been performed in 1.6% alginate (66.7 cP), which was the choice of carrier fluid.

Original languageEnglish
Pages (from-to)248-254
Number of pages7
JournalPDA Journal of Pharmaceutical Science and Technology
Issue number5
Publication statusPublished - 2002 Sep 1



  • Bacterial challenge test
  • Brevundimonas diminuta
  • Cell clumps
  • Filter validation
  • High viscosity fluid

ASJC Scopus subject areas

  • Pharmaceutical Science

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