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Comparison of contamination rates between preserved and preservative-free fluoroquinolone eyedrops
Mo Sae Kim1, Hong Kyun Kim, Joon Mo Kim
1Department of Ophthalmology, National Cancer Center, Goyang, South Korea.
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.
Insights
Preservative-free fluoroquinolone eye drops showed reduced antifungal effectiveness in challenge tests, though in-use tests found no contamination. Physicians should consider this difference when prescribing these antimicrobial agents.
Area of Science:
- Ophthalmology
- Microbiology
- Pharmaceutical Science
Background:
- Antimicrobial effectiveness of ophthalmic solutions is crucial for preventing eye infections.
- Preservative-free formulations are increasingly used, but their antimicrobial efficacy requires thorough evaluation.
- Benzalkonium chloride (BAC) is a common preservative in fluoroquinolone eye drops.
Purpose of the Study:
- To compare the antimicrobial effectiveness of preservative-free fluoroquinolone eye drops against BAC-preserved fluoroquinolones.
- To evaluate preservative efficacy using United States Pharmacopeia (USP) challenge and in-use tests.
Main Methods:
- Challenge Test: Four USP-listed microorganisms (Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Aspergillus niger) were inoculated into fluoroquinolone preparations. Microbial survivors were quantified at 7, 14, and 28 days.
- In-Use Test: 100 bottles of preservative-free fluoroquinolone eyedrops were collected from patients after one week of use. Bottle contents and tips were cultured for microbial contamination.
Main Results:
- Challenge Test: Preservative-free gatifloxacin and levofloxacin showed lower Log10 reduction against Aspergillus niger compared to preserved fluoroquinolones and preservative-free moxifloxacin.
- In-Use Test: No microbial contamination was detected in preservative-free fluoroquinolone bottles after one week of patient use.
Conclusions:
- Some preservative-free fluoroquinolone preparations exhibit reduced antifungal preservative effectiveness compared to preserved counterparts.
- Clinical awareness of these differences is important for appropriate antimicrobial prescribing in ophthalmology.
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