Formulation and testing of methazolamide cyclodextrin eye drop solutions

Hafrún Fridriksdóttir, Thorsteinn Loftsson*, Einar Stefánsson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


Methazolamide is a carbonic anhydrase inhibitor which has been used in oral formulations to treat glaucoma. Methazolamide has a limited aqueous solubility. The effects of three different water-soluble polymers on phase-solubility diagrams of methazolamide were determined in aqueous 2-hydroxypropyl-β-cyclodextrin (HPβCD) solutions. The polymers increased the stability constant (K(c)) of the drug-HPβCD complex from 28 M-1, when no polymer was present, to 69 M-1 when the solution contained HPβCD and 0.1% (w/v) hydroxypropyl methylcellulose (HPMC). The solubilizing effect of the HPβCD/HPMC combination on methazolamide was used to make aqueous eye drop solutions of methazolamide. The eye drop solutions were administrated topically to rabbits and the IOP lowering effect of the drug determined. The results show that, when formulated in aqueous HPβCD/HPMC solutions, methazolamide is a topically active IOP lowering agent. The 1% (w/v) methazolamide solution was shown to be almost as active as Blocadren® (0.5% w/v timolol). These results indicate that these types of HPβCD/HPMC low viscosity eye drop solutions are potent delivery Vehicles for topical delivery of carbonic anhydrase inhibitors to the eye.

Original languageEnglish
Pages (from-to)95-99
Number of pages5
JournalJournal of Controlled Release
Issue number1
Publication statusPublished - 1 Feb 1997

Bibliographical note

Funding Information:
This work was supported by the University of Iceland Research Fund.

Other keywords

  • Co-complexes
  • Cyclodextrin
  • Eye drops
  • Methazolamide
  • Polymers
  • Solubility


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