In the present investigation, a novel approach towards a complete separation of all 15 protease and reverse transcriptase inhibitors which are currently approved for use in highly active antiretroviral therapy in a single analytical run is presented. The developed method employs an acidic background electrolyte with sodium polyanethol sulfonate (SPAS) as polyanionic electroosmotic flow (EOF) modifier to establish a strong cathodic EOF, sodium dodecyl sulfate (SDS) as pseudostationary selector, and acetonitrile and ethanol as organic modifiers. Separation of the analytes is based on two different mechanisms. The more basic analytes are protonated at the prevailing pH conditions and thus migrate in front of the cathodic EOF, whereas the less basic and neutral analytes interact with the SDS and are retained after the EOF. By optimizing electrolyte pH, the amount of solvents and SDS concentrations in the background electrolyte it is possible to completely separate all compounds of interest.

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The aim of this study was to correlate results of therapeutic drug monitoring, genotypic resistance and viral response to lopinavir/ritonavir (LPV/r) or saquinavir/ritonavir (SQV/r) containing antiretroviral regimens. The retrospective short-term study included 20 patients with LPV/r and 20 patients with SQV/ r containing highly active antiretroviral therapy (HAART). At baseline 7 LPV/r patients and 10 SQV/r patients had CD4+T cell counts above 410 cells/Ill. After 6 months CD4+T cells had doubled in 5 LPV/r and 2 SQV/r patients. In LPV/r patients the mean serum concentration oflopinavir (LPV) was 2.6 ppm and 67 % of all LPV /r samples had 50 or fewer viral copies/ml. In SQV/r patients the mean serum concentration of saquinavir (SQV) was 2

Separation of 11 protease and reverse transcriptase inhibitors by capillary zone electrophoresisCapillary zone electrophoresis is employed for the simultaneous screening of protease and reverse transcriptase inhibitors which are used as antiretroviral therapy drugs against the Human Immunodeficiency Virus. Because of the basic character of the analytes, the electrophoretic system makes use of an acidic buffer electrolyte. In order to establish a strong anodic electroosmotic flow, a cationic surfactant is added to the background electrolyte. This causes the cationic analytes to migrate against the electroosmotic stream (counter-electroosmotic CE). The developed separation system permits a simultaneous separation of protease and reverse transcriptase inhibitors with good selectivity and sensitivity.