Stability study of fortified antibiotic eye drops with a spectrophotometric dosage

The manufacturing unit of our establishment produced 440 units of antibiotic eye drops in 2011. A 23% increase a year of the demand of these preparations imposes an optimization of the production. The freezing of these preparations allows rationalizing of the production by increasing the size of the batches produced. In this context, an evaluation of the stability of eye drops after freezing and storage at 4 ° was led.

The automaton of used dosage is Multispec® present in the unit. This automaton associated the UV-visible and infrared spectrophotometry. Initially used to measure the anticancer drugs, it allows an analytical validation of the preparations by identifying and by quantifying molecules by comparison to the integrated data base. The three antibiotics are not in the initial data base; a spectrum analysis was realized and referenced. A range of 14-point calibration was performed for every antibiotic. Every antibiotic has been frozen 1 month then defrosted, stored at 4 ° C and measured for 21 days to obtain kinetics of degradation.

The residual standard deviations of calibration curves of ceftazidime, amikacin and vancomycin were respectively 1.29%, 1.82% and 1.46%. This attests to the quality of the calibration ranges achieved. The spectral recognition of every antibiotic is 100%. The percentages of degradation of ceftazidime, amikacin and vancomycin were respectively 0.6%, 6.5% and 0% at day 7 after thawing and 100%, 12.7% and 0% at day 21.

This study allowed developing a method of dosage of fortified antibiotic eye drops with the Multispec®. The stability of 7 days is compatible with the use of these drops in the care departements .In practice, this assay will allow the validation of preservation by freezing and systematic dosage of these preparations to assure safety of use.