Buprenorphine assay and plasma concentration monitoring in HIV-infected substance users

A chromatographic method for monitoring BUP and its active metabolite, NBUP was investigated. An assay was developed that would facilitate BUP and ARV measurement from a single 3 mL blood sample (0.75 mL plasma required) in conjunction with a previously validated multiple ARV HPLC method. The method measures BUP and NBUP over the range from 0.25 to 50 ng/mL with mass spectrometry detection. Inter- and intra-assay variation was ≤11%, across the concentration range. The method quantitates BUP and NBUP plasma concentrations within the range of expected values from current BUP dosing guidelines. Use of this combined BUP and ARV plasma concentration monitoring approach for a representative patient receiving BUP, atazanavir and efavirenz demonstrated its clinical application.