Stability-indicating HPLC method to determine the stability of extemporaneously prepared vancomycin oral solution cups

Abstract

Purpose: To determine the stability of compounded sweetened vancomycin oral formulations in plastic unit dose cups stored up to 180 days under 2 temperature conditions: refrigeration (2°C-6°C) and room temperature (25°C with 60% relative humidity).

Methodology: A stability-indicating high-performance liquid chromatography (HPLC) method was developed to analyze vancomycin in the presence of degradation peaks. The stability of extemporaneously compounded vancomycin solution stored in oral unit dose cups was investigated using this method. The tested vancomycin oral solutions were compounded formulations of 125 mg/2.5 mL and 500 mg/10 mL. Three oral unit dose cups from each storage condition were withdrawn and assessed for stability on days 0, 3, 7, 15, 22, 30, 90, 120, 150, and 180 as per United States Pharmacopeia guidelines. The assay of vancomycin was carried out by using a calibrated stability-indicating HPLC method.

Results: The stability-indicating HPLC assay showed that vancomycin completely degraded within 2 hours when exposed to highly acidic or basic pH conditions. No precipitation, cloudiness, or color changes were observed during the study under either temperature condition. The HPLC assay revealed that vancomycin oral solution cups retained greater than 90% of the initial concentrations of vancomycin for 30 days when stored at room temperature (25°C and 60% relative humidity) and for 180 days with refrigeration (2°C-6°C).

Conclusion: Vancomycin oral formulations were stable for long-term storage periods beyond those specified in manufacture guidelines. Our data suggests the extended stability of vancomycin oral solutions compounded for hospital use can be extended.

Keywords: HPLC; compounding; oral solutions; stability; stability-indicating; vancomycin.