title: High-performance liquid chromatographic determination of usnic acid in plasma.
abstract: A high-performance liquid chromatographic method for the determination of usnic acid in human plasma using diclofenac sodium as internal standard is described. Plasma proteins were precipitated with methanol. A 250 mm x 4 mm I.D. Nucleosil. C18 (5 microns) column with a mobile phase consisting of methanol-phosphate buffer (pH 7.4) (70:30, v/v) was used. Chromatography was performed at ambient temperature with flow-rate of 1 ml min-1 and ultraviolet detection at 280 nm. Each analysis required no longer than 7 min. Quantification was achieved by measurement of the peak-height ratio and the absolute recovery varied from 93.8 to 97.3%. The limit of quantitation of usnic acid in plasma was 0.25 micrograms ml-1. The intra-day relative standard deviation (R.S.D.) ranged from 1.24 to 4.53% and the inter-day R.S.D. from 2.23 to 8.25% at three different concentrations. The method was applied to the determination of plasma levels of usnic acid after intravenous and oral administration to study its disposition in a healthy male rabbit.
authors.affiliation: University College of Pharmaceutical Sciences, Kakatiya University, Warangal, India.
authors.forename: D
authors.initials: D
authors.lastname: Venkataramana
authors.forename: D R
authors.initials: DR
authors.lastname: Krishna
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001572:Benzofurans / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D011817:Rabbits; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D001572:Benzofurans