Ocular delivery of cyclosporin A I. Design and characterization of cyclosporin A-loaded positively-charged submicron emulsion

S. Tamilvanan, K. Khoury, D. Gilhar, S. Benita*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Cyclosporin A, a non-polar cyclic polypeptide, was incorporated successfully in a positively-charged submicron emulsion delivery system. Physicochemical characterizations such as particle size (220-240 nm), creaming rate and drug content suggested that the submicron emulsion formulation was able to withstand thermic and mechanical shocks while showing virtually no sign of drug nanoprecipitation or crystallization within the emulsion upon storage at 4, 25 and 37°C over a period of up to six months although cyclosporin is notorious for its tendency to precipitate out in conventional oil/water systems in which it is fully dissolved initially. The drug probably has a reasonably high degree of drug solubilization in the inner oil core phase of the emulsion preventing the crystallization. However, the pH and zeta potential of the final emulsion decreased progressively at the highest storage temperature studied compared to the lower temperatures, during the stipulated storage time. This most probably indicates the formation of free fatty acids from phospholipids present in the formulation, which are known to reduce the emulsion pH value, leading to a decrease in the absolute zeta potential value but without reversing the charge.

Original languageEnglish
Pages (from-to)421-426
Number of pages6
JournalS.T.P. Pharma Sciences
Volume11
Issue number6
StatePublished - 2001

Keywords

  • Cyclosporin A
  • pH
  • Stability
  • Submicron emulsion
  • Zeta potential

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