Solid phase extraction and high performance liquid chromatographic determination of doxophylline in plasma

A sensitive and selective high performance liquid chromatographic doxophylline assay with ultraviolet detection has been developed for plasma samples. The drug is isolated from biological samples with a reversed phase C18 disposable extraction column. Plasma standard curves are linear for concentrations of doxophylline from 0.03 to 10 mg/L. At the therapeutic range concentrations, the recoveries are better than 96.9%. The coefficients of variation for the procedure are 4.1% and 2.7% for the concentrations 0.03 mg/L and 10 mg/L, respectively. By this method, pharmacokinetic profiles are obtained for six adult volunteers.