In vitro enantioselective displacement of propranolol from protein binding sites by acetyl salicylic acid and salicylic acid

The influences of acetyl salicylic acid (ASA) and salicylic acid (SA) on the enantioselective binding of propranolol (PL) and its enantiomers to plasma proteins and human serum albumin (HSA) were investigated. The equilibrium dialysis was employed for protein binding studies. We observed statistically significant displacement of racemic-PL, (+)-(R)-PL, and (−)-(S)-PL (0.1–10 μM) from their protein binding sites by ASA (200 μg/ml) and SA (100 μg/ml). ASA and SA displaced PL stereoselectivly from its binding sites. We concluded that ASA and its metabolite SA could change R/S ratio of PL unbound fractions and they might affect pharmacokinetic properties of PL.