EVALUATING THE CAPACITY OF HUMAN SERUM ALBUMIN TO REDUCE NON-SPECIFIC BINDING OF MELOXICAM IN THE ULTRAFILTRATION PROCESS

Due to the importance that plasma protein binding of drugs plays and the constant interest to optimize study methods of the process, this study aimed to test the capacity of a human serum albumin solution to reduce non-specific binding of highly bound meloxicam, based on the ability of the protein to block most non-specific binding sites of the ultrafiltration devices. Samples of meloxicam and internal standard piroxicam were prepared in both phosphate-buffered saline solution, commonly used in biological research, and 5% human serum albumin solution. After the ultrafiltration process, the free drug fraction was analysed using a reversed phase HPLC-UV method. A decrease in the concentration of meloxicam after ultrafiltration in both matrices was observed, the decrease being higher in the case of phosphate-buffered saline solution. The mean determined degree of binding to albumin for meloxicam was 55%. The high decrease in concentration for meloxicam in the non-proteic matrix indicates a very high degree of non-specific binding, phenomenon which appears to be indeed reduced for the samples prepared in human serum albumin solution. The study also emphasises the very close attention that should be paid to the preparation and processing of samples in protein matrices and to the experimental conditions.