Pharmaceutisch Weekblad

, Volume 9, Issue 1, pp 29–32 | Cite as

Incompatibility of indometacin and benzalkonium in eye drops due to ion-pair formation

  • S. M. Dreijer-Van der Glas
  • A. Bult
Short Communications


Eye drop formulations containing indometacin and benzalkonium salt often show an opalescence as a result of ion-pair formation. The insoluble ion pair was isolated and characterized by infrared and ultraviolet spectroscopy and thin layer chromatography. This ion pair is also responsible for the bad assay results of benzalkonium using the ion-pair extraction method with bromothymol blue as counterion. The distribution

Key words

Indometacin Benzalkonium Ion pair Incompatibility 


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Copyright information

© Royal Dutch Association for Advancement of Pharmacy 1987

Authors and Affiliations

  • S. M. Dreijer-Van der Glas
    • 1
  • A. Bult
    • 1
  1. 1.Department of Pharmaceutical Analysis, Subfaculty of PharmacyState University of UtrechtGH UtrechtThe Netherlands

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