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Stability and antibacterial potency of ceftazidime and vancomycin eyedrops reconstituted in BSS ® against Pseudomonas aeruginosa and Staphylococcus aureus
Author(s) -
Karampatakis Vasileios,
Papanikolaou Theoharis,
Giannousis Michael,
Goulas Antonis,
Mandraveli Kaliopi,
Kilmpasani Maria,
AlexiouDaniel Stella,
MirtsouFidani Vassiliki
Publication year - 2009
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2008.01306.x
Subject(s) - potency , ceftazidime , staphylococcus aureus , pseudomonas aeruginosa , vancomycin , chemistry , antibacterial activity , microbiology and biotechnology , minimum inhibitory concentration , antimicrobial , bacteria , in vitro , biology , biochemistry , organic chemistry , genetics
. Purpose: We aimed to study the stability and the in vitro antibacterial potency of ceftazidime and vancomycin eyedrops against Pseudomonas aeruginosa and Staphylococcus aureus , respectively, under different storage temperatures and light conditions. Methods: Solutions of ceftazidime 50 mg/ml and vancomycin 50 mg/ml were prepared by reconstituting with balanced salt solution (BSS ® ) and stored at 4 °C and at 24 °C with and without exposure to light. The minimum bactericidal concentrations against P. aeruginosa and S. aureus were measured to evaluate the antimicrobial potency over a 4‐week period. Changes in the pH values and physical characteristics of the solutions were recorded over the same period of time. Results: The antibacterial potency of ceftazidime decreased significantly from days 3 and 7 onwards at storage temperatures of 24 °C and 4 °C, respectively, but was not affected by light exposure. The pH value progressed from acidic to alkaline, peaking at day 3, in all solutions. The antibacterial potency of vancomycin remained stable during the 4‐week period, but its pH showed a slight progression from acidic to less acidic, in all solutions. Conclusions: Ceftazidime eyedrops in BSS ® appear to remain effective against P. aeruginosa for ≥ 7 days when stored at 4 °C, but were less effective when stored at 24 °C. Loss of antibacterial potency coincides with the appearance of visual and olfactory signs of degradation. The transient rise in pH at day 3 is a matter of possible concern, however, as it may affect patient tolerance. By contrast, vancomycin eyedrops in BSS ® can be safely used for ≥ 4 weeks, stored at either 4 °C or 24 °C.