Stability of cefepime in aqueous eye drops.

The aim of the studies was to determine HPLC the stability of cefepime in 1% and 5% buffered eye drops of developed formulary composition, which were stored for 30 days at the temperature of 4 degrees C and 20 degrees C, protected from light. Separation was performed on RP18 Gemini octadecylsilane column (250 mm x 4.6 mm, 5.0 microm) at a temperature of 25 degrees C. The mobile phase consisted of 0.015 M solution of sodium salt of pentane sulphonic acid brought to pH 4.0 with glacial acetic acid and 45% KOH solution and acetonitrile 94:6 w/w, with detection of 254 nm. The method was linear in the range of 12.6-125 microg/ml (R2 = 0.9996). The limit of detection (LOD) was 3 microg/ml and limit of quantification (LOQ) was 10 microg/ml. 10% degradation of cefepime in 1% and 5% buffered eye drops stored at the temperature of 4 degrees C, depending on the composition of the eye drops, occurred after 21-27 days in 1% eye drops and 18-21 days in 5% eye drops. In the eye drops, which were stored at the temperature of 20 degrees C, 10% degradation of cefepime took place on the third day of storage regardless of formulary composition of 1% and 5% drops. Cefepime stability lasting a couple of weeks in 1% and 5% solution allows extemporaneous preparation of buffered eye drops containing cefepime.