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J Med Assoc Thai. 2005 Nov;88 Suppl 9:S6-10.

Sterility of non-preservative eye drops.

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  • 1Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.



To assess microbial contamination of common non-preservative eye drops stored at 4 degrees C and non-preservative fortified antibiotic eye drops used in a hospital inpatient setting.


A prospective study of the sterility of non-preservative eye drops was examined by dividing the patients into 2 groups. Group 1 composed of 5 samples of each ophthalmic preparation, which consisted of fortified antibiotics (vancomycin, cefazolin, gentamicin, and amikacin), non-preservative steroid eye drops (1% methylprednisolone and 0.01% dexamethasone), and 20% autologous serum stored at 4 degrees C. Group 2 was composed of 28 samples of fortified vancomycin and 23 samples of fortified amikacin used in an inpatient setting for 1 week and kept in 4 degrees C for 28 days. The contamination was assessed at the day of preparation and then at day 4, 7, 14, 21, 28 of all medications except autologous serum was done up to day 84. The sterility was examined by the culturing on tryptic soy broth and thioglycolate broth.


In group 1 and 2, no contamination was detected in any samples within 4 weeks and up to 12 weeks for autologous serum.


Non- preservative topical eye drops can be safely kept at 4 degrees C without contamination for 4 weeks and 12 weeks for 20% autologous serum drop. For topical antibiotics, under a strict protocol for preparation and usage might be used without significant risk of bacterial contamination for 4 weeks.

[PubMed - indexed for MEDLINE]
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