[Binding of racemic indoprofen and its enantiomers to human serum albumin].

Binding of Racemic Indoprofen and its Enantiomers to Human Serum Albumin. The binding to 2% and 4% human serum albumin (HSA) of (+/-)-indoprofen, (-)-indoprofen, and (+)-indoprofen was examined applying a modified ultrafiltration process. The binding properties to HSA were characterized by determining the unbound portions of the drug (a), the overall binding constants (K1), the free reaction energy (delta F degrees), the apparent binding constants (k*), and slope (m). The following results were obtained: 1. Racemic indoprofen and its enantiomers show a high affinity to human serum albumin (a = 1-2%). 2. At higher HSA concentrations the free portion (a) diminishes. 3. The affinity to HSA is reduced in the order of levo-indoprofen racemic indoprofen, and dex-indoprofen.