Reversibility of protein binding of penicillins: an in vitro study employing a rapid diafiltration process.

The reversibility of human serum protein binding of oxacillin, nafcillin, and cephalothin was investigated by using a diafiltration technique. While the temperature, pH, and protein concentration were kept constant, 20% of the serum volume was exchanged every 4 to 5 min. The binding of all three drugs was rapidly reversible, and the percentage of protein binding remained the same throughout the experiment.