title: In vitro protein binding and tissue distribution of D(+) usnic acid.
abstract: In vitro protein binding of D(+) usnic acid in rabbit plasma and purified bovine serum albumin was investigated by equilibrium dialysis. The drug was highly protein bound, approximately 99.2%, and the extent of protein binding remained constant at usnic acid concentrations in the range of 1-5 micrograms/ml. The extent of binding, however, tended to decrease at low albumin concentrations and higher drug concentrations; Scatchard plot analysis indicated the existence of two classes of binding sites with association constants of 34.3 x 10(-6) and 1.43 x 10(-6) M respectively. Tissue distribution studies of usnic acid were undertaken in rats following i.p. administration. Usnic acid was well distributed into well perfused organs. The tissue/plasma ratio in lungs was high, which could be advantageous in a therapeutic agent for pulmonary tuberculosis.
authors.affiliation: University College of Pharmaceutical Sciences, Kakatiya University, Warangal, India.
authors.forename: D R
authors.initials: DR
authors.lastname: Krishna
authors.forename: D V
authors.initials: DV
authors.lastname: Ramana
authors.forename: N V
authors.initials: NV
authors.lastname: Mamidi
mesh_terms: D000818:Animals; D001572:Benzofurans / Q000097:blood / Q000493:pharmacokinetics*; D001798:Blood Proteins / Q000378:metabolism; D003956:Dialysis; D008297:Male; D011485:Protein Binding; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D012710:Serum Albumin, Bovine / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D001572:Benzofurans; D001798:Blood Proteins; C073339:usnic acid; D012710:Serum Albumin, Bovine