Effect of cucurbit[n]urils on tropicamide and potential application in ocular drug delivery

Na'Il Saleh, Mohammed A. Meetani, Leena Al-Kaabi, Indrajit Ghosh, Werner M. Nau

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

The supramolecular interactions of the ocular drug tropicamide (TR) with cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) were investigated in aqueous solutions by using 1H NMR, ESI-MS and UV-vis spectroscopic techniques. The results indicate a 1:1 binding stoichiometry of TR with CB7 and CB8. The binding constants of TR in its protonated form were higher (e.g. K = 4 × 10 6M -1 with CB8) than in its neutral form (e.g. K = 1.4 × 10 4M -1 with CB8), which led to a complexation-induced increase in its pK a value of ca. 0.5 and 2 units with CB7 and CB8, respectively. In the presence of about 1% (w/v) CB8, the ionisation degree of 0.1% (w/v) TR was increased from 2% to 62% at neutral pH. The increase in the pK a value and thus stabilisation of the protonated TR species at neutral pH is discussed in the context of supramolecular drug delivery of ophthalmologic drugs.

Original languageEnglish
Pages (from-to)654-661
Number of pages8
JournalSupramolecular Chemistry
Volume23
Issue number9
DOIs
Publication statusPublished - Sep 2011

Keywords

  • Cucurbiturils
  • Drug ionisation
  • Host-guest complexes
  • PK shifts
  • Tropicamide

ASJC Scopus subject areas

  • Chemistry(all)

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