Related Experiment Video
Updated: Aug 8, 2026
Encapsulated Cell Technology for the Delivery of Biologics to the Mouse Eye
Published on: March 30, 2020
Sterility of non-preservative eye drops
Pinnita Prabhasawat1, Suksri Chotikavanich, Amornrut Leelaporn
1Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand. sippb@mahidol.ac.th
Objectives:
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.
Material And Method:
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.
Results:
In group 1 and 2, no contamination was detected in any samples within 4 weeks and up to 12 weeks for autologous serum.
Conclusion:
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.
Insights
Non-preservative eye drops, including fortified antibiotics and autologous serum, remained sterile for up to 4 weeks when refrigerated at 4 degrees C. Autologous serum drops were safe for 12 weeks, indicating safe storage practices for ophthalmic preparations.
Area of Science:
- Ophthalmology
- Microbiology
- Pharmaceutical Science
Background:
- Preservative-free eye drops are crucial for patients with ocular surface disease.
- Refrigerated storage is often necessary for compounded ophthalmic preparations, including fortified antibiotics and autologous serum.
- Assessing the microbial contamination risk of these preparations under specific storage conditions is vital for patient safety.
Purpose of the Study:
- To evaluate the microbial contamination of common non-preservative eye drops stored at 4°C.
- To assess the sterility of non-preservative fortified antibiotic eye drops and autologous serum used in a hospital inpatient setting.
Main Methods:
- A prospective study involving two groups of ophthalmic preparations stored at 4°C.
- Group 1: Fortified antibiotics (vancomycin, cefazolin, gentamicin, amikacin), non-preservative steroids, and 20% autologous serum.
- Group 2: Inpatient-use fortified vancomycin and amikacin. Sterility assessed via broth culturing at various time points up to 84 days.
Main Results:
- No microbial contamination was detected in any samples within the first 4 weeks of storage at 4°C.
- Autologous serum samples remained sterile for up to 12 weeks.
Conclusions:
- Non-preservative topical eye drops, including fortified antibiotics, can be safely stored at 4°C for up to 4 weeks without significant risk of contamination.
- 20% autologous serum drops are safe for storage at 4°C for up to 12 weeks.
- Strict protocols for preparation and usage are essential for the safe use of topical antibiotics.
Related Concept Videos
01:23Ophthalmic Drug Delivery Systems
01:22Microbiome of the Eye
01:22Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence