Concentration and bioavailability of ciprofloxacin and teicoplanin in the cornea

¹ Medical Microbiology, Royal Liverpool University Hospital, Liverpool, United Kingdom; St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom
² Medical Microbiology, Royal Liverpool University Hospital, Liverpool, United Kingdom
³ St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom
⁴ Centre for Antimicrobial Research and Evaluation, North Bristol NHS Trust, Bristol, United Kingdom

^* To whom correspondence should be addressed. E-mail: s.b.kaye{at}liverpool.ac.uk.

	Abstract

Purpose. To investigate the concentration and bioavailability of ciprofloxacin and teicoplanin in the cornea. Method. A biological assay was developed using corneal tissue as a carrier for the antimicrobial. Concentration and biological activity were determined using a chemical assay and zone of inhibition (ZOI) around corneal samples with epithelial and endothelial surfaces in contact with indicator organism. Patients undergoing penetrating keratoplasty received ciprofloxacin 0.3% or teicoplanin 1%. Results. There were good correlations between antimicrobial concentration and ZOI, using filter paper and corneal discs (R2 > 92%). Of 33 patients, mean (median) concentration of ciprofloxacin in the cornea was 1.37 mg/L (0.46 mg/L) and 1.89mg/L (1.44 mg/L) (bioassay) epithelial and endothelial orientations, and 14.87mg/L (7.41) in the cornea and 0.51 mg/L (0.42) in the aqueous (chemical assay). For teicoplanin, mean (median) concentration in the cornea was 9.58 mg/L (0 mg/L) epithelial and 4.78 mg/L (0 mg/L) (bioassay) endothelial orientations. Using a chemical assay teicoplanin could not be detected in the cornea or aqueous at lower limit of detection of 3.6mg/L. Conclusion. The ZOI produced by corneal tissue provides a potential bioassay of antimicrobial activity and concentration. Although in contrast to teicoplanin ciprofloxacin shows good corneal penetration, with high endothelial to epithelial levels, only approximately 10% of measured levels using a chemical assay are available using a bioassay. Teicoplanin shows relatively poor corneal penetration through an intact epithelium. These methods may be useful to evaluate biological activity across the cornea of antimicrobials introduced into ophthalmic practise to deal with changing bacteria resistance.

Key Words: antibiotics, corneal ulceration, pharmacokinetics

This article has been cited by other articles:

				S. Kaye, S. Tuft, T. Neal, D. Tole, J. Leeming, F. Figueiredo, M. Armstrong, P. McDonnell, A. Tullo, and C. Parry Bacterial Susceptibility to Topical Antimicrobials and Clinical Outcome in Bacterial Keratitis Invest. Ophthalmol. Vis. Sci., January 1, 2010; 51(1): 362 - 368. [Abstract] [Full Text] [PDF]