Elsevier

Biochemical Pharmacology

Volume 46, Issue 10, 17 November 1993, Pages 1721-1731
Biochemical Pharmacology

Research paper
Study of interaction of carprofen and its enantiomers with human serum albumin—I: Mechanism of binding studied by dialysis and spectroscopic methods

https://doi.org/10.1016/0006-2952(93)90576-IGet rights and content

Abstract

The binding of carprofen, a non-steroidal anti-inflammatory drug of the aryl propionic acid class [2-(6-chlorocarbazole)propionic acid], and its enantiomers to human serum albumin (HSA) has been studied by dialysis and spectroscopic methods. Binding parameters obtained by different methods were in close agreement. The binding of carprofen to HSA by both fluorescence and equilibrium dialysis (ED) methods is characterized by two sets of association constants [K1 = 5.1 × 106 M−1 (fluorescence) and 3.7 × 106M (ED), K2 = 3.7 × 105M−1 (fluorescence) and 1.3 × 105 M−1 (ED)]. The S(+)-enantiomer of carprofen showed slightly higher affinity for HSA than its corresponding antipode by both methods. Different analyses of the binding to HSA suggested the presence of one high affinity site and five to seven low affinity sites for carprofen and its enantiomers on HSA. Fluorescence displacement data implied that carprofen primarily binds to site II, the benzodiazepine site, while the low affinity site of carprofen is site I, the warfarin site. Circular dichroism data suggested different mechanisms for the high affinity and the low affinity binding of carprofen to HSA. The data are consistent with the major part of the binding energy at site II being electrostatic and hydrophobic interactions, whereas for the low affinity binding, hydrophobic interactions. Binding was exothermic, entropy driven and spontaneous, as indicated by the thermodynamic analyses. From binding data with chemically modified HSA derivatives, it is likely that tyrosine, lysine and histidine residues are especially involved in carprofen binding to HSA, and it is most likely that the high affinity binding of carprofen is located in the N-terminal part of domain III or that section of protein plus the C-terminal part of domain II of the HSA molecule. When the binding of carprofen to HSA was compared to the binding of carprofen methyl ester to HSA (K = 0.1 × 106M−1), the carboxyl group of carprofen was found to play an important role especially in the high affinity binding of carprofen to HSA. The high affinity of carprofen to HSA was independent of the conformational changes on HSA caused by N-B transition.

References (49)

  • J.B. Pedersen et al.

    Contamination by a competitive ligand as an explanation for the inverse dependence of HABA binding parameters upon the protein concentration

    Biochem Pharmacol

    (1989)
  • K.J. Fehske et al.

    A highly reactive tyrosine residue as part of the indole and benzodiazepine binding site of human serum albumin

    Biochim Biophys Acta

    (1979)
  • WJ Leonard et al.

    A structural transformation of bovine and human serum albumins in alkaline solution as revealed by rotatory dispersion studies

    J Biol Chem

    (1963)
  • AJ Hutt et al.

    The importance of sterochemistry in the clinical pharmacokinetics of the 2-arylpropionic acid non-steroidal antiinflammatory drugs

    Clin Pharmacokinet

    (1984)
  • JH Lin et al.

    Protein binding as a primary determinant of the clinical pharmacokinetic properties of non-steroidal antiinflammatory drugs

    Clin Pharmacokinet

    (1987)
  • S. Wanwimolruk et al.

    Protein binding of some non-steroidal antiinflammatory drugs in rheumatoid arthritis

    Clin Pharmacokinet

    (1982)
  • S Wanwimolruk et al.

    Structural requirements for drug binding to site II on human serum albumin

    Mol Pharmacol

    (1983)
  • B Honoré et al.

    Albumin binding of antiinflammatory drugs. Utility of a site oriented versus a stoichiometric analysis

    Mol Pharmacol

    (1984)
  • G Sudlow et al.

    Further characterization of specific drug binding sites on human serum albumin

    Mol Pharmacol

    (1976)
  • DJ Birkett et al.

    Fluorescent probe studies of albumin binding sites

    Acta Pharm Suec

    (1980)
  • WJ Jusko

    Pharmacokinetics in disease states changing protein binding

  • WJ Jusko et al.

    Plasma and tissue protein binding of drugs in pharmacokinetics

    Drug Metab Rev

    (1976)
  • H Kurz et al.

    Binding of drugs to tissue

    Drug Metab Rev

    (1983)
  • JK Stolenborg et al.

    High performance liquid chromatographic determination of steroselective disposition of carprofen in humans

    J Pharm Sci

    (1981)
  • Cited by (0)

    View full text