title: Antibacterial activity of the white precipitate formed on the corneal surface after treatment with ciprofloxacin ophthalmic solution.
abstract: OBJECTIVE
  To determine the antibacterial activity of the white crystalline precipitate formed on the corneal surface after topical administration of 0.3% ciprofloxacin ophthalmic solution by microbiologic assay.
  
  
  METHODS
  White crystalline precipitate formed on the corneal surface of seven patients was scraped and individually dissolved in sterile distilled water. Quantification by high-performance liquid chromatography (HPLC) and microbiologic assay of ciprofloxacin in the precipitate solutions were done. Microbiologic assay was performed by agar diffusion method against Klebsiella pneumoniae.
  
  
  RESULTS
  By HPLC, concentrations of ciprofloxacin were estimated to be 1.5-60 microg/ml in the dissolved precipitate obtained from six patients, whereas the concentrations based on microbiologic assay varied from 1.6 to 16.1 microg/ml. Ciprofloxacin was not detected by either method in the precipitate obtained from one patient. The antibacterial activity (microg/ml) determined by microbiologic assay was not related to the actual amount of ciprofloxacin in the solutions as estimated by HPLC in cases 1, 2, 4, and 7. It was almost the same in the solutions from cases 5 and 6.
  
  
  CONCLUSIONS
  The white crystalline precipitate formed on the corneal surface after topical administration of 0.3% ciprofloxacin ophthalmic solution exhibited bacterial inhibitory activity, indicating that the precipitate may function as a drug depot.
authors.affiliation: Vision Research Foundation, Sankara Nethralaya, Chennai, India. mdsaaa35@giasmd01.vsnl.net.in
authors.forename: H N
authors.initials: HN
authors.lastname: Madhavan
authors.forename: S K
authors.initials: SK
authors.lastname: Rao
authors.forename: P R
authors.initials: PR
authors.lastname: Joseph
authors.forename: K N
authors.initials: KN
authors.lastname: Sulochana
mesh_terms: D000328:Adult; D000890:Anti-Infective Agents / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D011232:Chemical Precipitation; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D002939:Ciprofloxacin / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D003315:Cornea / Q000737:chemistry*; D003320:Corneal Ulcer / Q000188:drug therapy*; D003460:Crystallization; D015818:Eye Infections, Bacterial / Q000188:drug therapy*; D006801:Humans; D005779:Immunodiffusion; D007711:Klebsiella pneumoniae / Q000187:drug effects*; D008297:Male; D008826:Microbial Sensitivity Tests; D009883:Ophthalmic Solutions / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000890:Anti-Infective Agents; D009883:Ophthalmic Solutions; D002939:Ciprofloxacin