Rapid HPLC determination of pioglitazone in human plasma by protein precipitation and its application to pharmacokinetic studies.

A simple and rapid HPLC method with UV detection was developed for the determination of pioglitazone in human plasma. The method was based on protein precipitation using perchloric acid on an ODS column. The mobile phase consisted of a mixture of phosphate buffer, methanol, acetonitrile, and 12 M perchloric acid (54 + 33 + 12 + 1, v/v/v/v). The UV detector was set at 269 nm. Under these conditions, the retention time of pioglitazone was 5.2 min. The standard curve was linear over the range of 50-2000 ng/mL pioglitazone in human plasma. The within-day and between-day precision studies showed high reproducibility, with CV less than 5%. The LOQ was 44.2 ng/mL. The method has been applied to a bioequivalence study after administration of pioglitazone as 30 mg tablets to 12 healthy volunteers.