Propofol binding to human blood proteins.

The binding of the intravenous anesthetic propofol (CAS 2078-54-8) to human native plasma, hemoglobin and serum albumin was studied by means of equilibrium dialysis. Propofol binding to plasma over the large concentration range from 0.04 to 150 micrograms/ml was independent on the substrate concentration and amounted 97.4-98.6%. Serum albumin and hemoglobin also showed a marked binding for propofol. A 4% solution of albumin bound 88.7% and hemoglobin 86.2% of the anesthetic. In studies with constant protein concentration and variation of the propofol concentration a decrease of the percentage bound with increasing substrate concentration was seen for hemoglobin, indicating saturable binding sites. The opposite was found for the interaction between propofol and albumin: increase of the binding extent with increasing substrate concentration.