Determination of zidovudine/lamivudine/nevirapine in human plasma using ion-pair HPLC

A new high-performance liquid chromatography (HPLC) assay was developed for the simultaneous determination of zidovudine (AZT)lamivudine (3TC)/nevirapine in human plasma. Plasma samples were treated using a solid-phase extraction procedure. The compounds were separated using a mobile phase of 20 mM sodium phosphate buffer (containing 8 mM I-octanesulfonic acid sodium salt)-acetonitrile (86:14, v/v) with pH adjusted to 3.2 with phosphoric acid on an octylsilane column (150 x 3.9 mm i.d.) with UV detection at 265 nm. Aprobarbital was chosen as the internal standard (IS). The method was validated over the range of 57.6-2880 ng/ml for AZT, 59.0-17650 ng/ml for 3TC and 53.2-13300 ng/ml for nevirapine. The method was shown to be accurate, with intra-day and inter-day accuracy from 0.1 to 11% and precise, with intra-day and inter-day precision from 0.4 to 14%. Extraction recoveries of the analytes and IS from plasma were higher than 92%. The assay should be suitable for use in pharmacokinetic studies and routine plasma monitoring of this triple-drug therapy in AIDS patients. (C) 2002 Elsevier Science B.V. All rights reserved.