Stability of cefuroxime in 1% and 5% buffered eye drops determined with HPLC method.

The aim of the studies was to develop formulary technologies of 1% and 5% eye drops containing cefuroxime with stability of at least 10-12 days. The stability was defined as the time required to reach the cutoff value of 10% degradation of cefuroxime in the drops, as determined using an HPLC assay. The drops should have such properties as optical clarity, pH in the range of 3.5 to 8.5 and osmotic pressure not lower than 280 mOsm/L. Additionally, drops of enhanced viscosity within the range 7-9 mPaxs were developed. Drops (1% and 5%) were prepared under aseptic conditions by dissolving Biofuroksym (Cefuroxime natricum) IBA Bioton--the form of the drug for dry injections--in citrate buffer of pH 6.05-6.28. Polyvinyl alcohol was used to increase the viscosity of the drops. Phenylmercuric borate at the final concentration of 0.001% was used together with beta-phenylethyl alcohol at the final concentration of 0.4% to preserve the drops. The drops were stored for 30 days in tightly closed glass bottles at the temperature of 4 degrees C and 20 degrees C, protected from light. As the course of the infection may differ in intensity, location and the area of the infection in the eye, the composition of the drops was developed at two concentrations (1% and 5%), and five formulary versions for each concentration were prepared. The concentration of cefuroxime in the drops was determined every three days using HPLC. Such properties as pH, osmotic pressure and viscosity were also examined. Additionally, organoleptic analysis (clarity, color, odor) was performed. Physical and chemical properties of all formulations of 1% and 5% drops containing cefuroxime prepared in citrate buffer of pH 6.05-6.28 met the standards set in the objective of the work. The stability of cefuroxime in buffered drops stored at the temperature of 4 degrees C, determined with HPLC as the time of 10% degradation of cefuroxime, was 15 days for 1% and 5% drops. In the drops, which were buffered and of increased viscosity, the times of 10% cefuroxime degradation were 18 days for 1% drops and 30 days for 5% drops. The preservatives added to the buffered drops did not lower their stability. Osmotic pressure, pH and viscosity of the drops during the period of 30-day-storage at the temperature of 4 degrees C met the requirements acceptable for the eye drops. The stability of 1% and 5% buffered drops containing cefuroxime stored at the temperature of 4 degrees C allows preparing the drops in pharmacies on the basis of doctor's prescription. Depending on the character and the course of the infection the drops can be prepared at the concentration of 1% and 5% following the composition of the selected formulation which would meet the individual needs of the patient's therapy.