Solid-phase extraction combined with dispersive liquid-liquid microextraction/HPLC-UV as a sensitive and efficient method for extraction, pre-concentration and simultaneous determination of antiretroviral drugs nevirapine, efavirenz and nelfinavir in pharmaceutical formulations and biological samples.

Therapeutic drug monitoring (TDM) of antiretroviral drugs requires accurate and precise analysis of their trace amounts in plasma samples. Solid-phase extraction (SPE) coupled with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) was introduced as a simple and sensitive method for extraction, pre-concentration and simultaneous determination of efavirenz (EFV), nelfinavir (NFV) and nevirapine (NVP) in human plasma and pharmaceutical formulations by using high performance liquid chromatography (HPLC) with UV detection. A response surface methodology (RSM) based on central composite design (CCD) was used for optimizing the main variables in the extraction procedure.