Comparison of contamination rates between preserved and preservative-free fluoroquinolone eyedrops.
BACKGROUND
To evaluate the antimicrobial effectiveness of preservative-free fluoroquinolone products compared with benzalkonium chloride containing fluoroquinolones using the challenge test provided by the United States Pharmacopeia (USP) and the in-use test.


METHODS
1. Challenge test: to compare the growth of microorganisms between different fluoroquinolone preparations, four test organisms, including Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger were chosen among five microorganisms listed by USP 2004. The inoculated products were sampled for microbial survivors at days 7, 14, and 28 following initial inoculation at room temperature. The number of surviving organisms were calculated as a Log10 reduction from the original inocula. 2. In-use test: a total of 100 bottles were collected after instillation of preservative-free fluoroquinolone eyedrops in volunteer patients after 1 week of use. The remaining fluid and tips of the bottles were cultured. Colonies on the plates were counted at the end of the incubation period. All microorganisms were identified by Gram staining and biochemical assays.


RESULTS
1. Challenge test: preservative-free gatifloxacin and levofloxacin demonstrated a lower log reduction against A. niger than preserved fluoroquinolones and preservative-free moxifloxacin at all time points. 2. In-use test: There was no contamination identified on plates inoculated by preservative-free quinolone bottles after 1 week of use in this study.


CONCLUSIONS
Physicians should be aware of the lower antifungal preservative effectiveness of some preservative-free fluoroquinolone preparations than preserved ones.
Department of Ophthalmology, National Cancer Center, Goyang, South Korea.
Mo Sae
MS
Kim
Hong Kyun
HK
Kim
Joon Mo
JM
Kim
Chul Young
CY
Choi
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001234:Aspergillus niger / Q000187:drug effects / Q000254:growth & development; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development*; D001431:Bacteriological Techniques; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects / Q000254:growth & development; D015169:Colony Count, Microbial; D004340:Drug Contamination; D005128:Eye Diseases / Q000188:drug therapy; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology* / Q000627:therapeutic use; D005658:Fungi / Q000187:drug effects / Q000254:growth & development*; D000077734:Gatifloxacin; D006801:Humans; D064704:Levofloxacin; D008297:Male; D008875:Middle Aged; D015242:Ofloxacin / Q000627:therapeutic use; D009883:Ophthalmic Solutions / Q000494:pharmacology; D011310:Preservatives, Pharmaceutical / Q000494:pharmacology*; D011446:Prospective Studies; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development
D000900:Anti-Bacterial Agents; D001548:Benzalkonium Compounds; D024841:Fluoroquinolones; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical; D064704:Levofloxacin; D015242:Ofloxacin; D000077734:Gatifloxacin