Abacavir (ABC), Efavirenz (EFV), Lamivudine (3 TC) and Nelfinavir (NFV) are antiretrovirals (ARV) drugs frequently prescribed to treat human immunodeficiency virus (HIV) infection [1]. Therapy based on antiretroviral combination is used for patient treatment infected with HIV. Accurate dose of ARV is essential in this kind of therapy for guaranteeing viral suppression, as well as to avoid patient intoxication