Determination of buprenorphine in plasma by liquid chromatography: application to heroin-dependent subjects

A rapid, sensitive, precise and accurate HPLC assay with UV detection was developed for the determination of buprenorphine (BN) in human plasma. This method involved a two-step extraction in the presence of clothiapine as internal standard. The compounds were chromatographied on a reversed-phase Spherisorb C8 column with a mobile phase consisting of 0.06 M KH2PO4/Na2HPO4 pH 6.4-acetonitrile-triethylamine-Pic B5 (520:480:0.5:15, v/v) and detected at 214 nm. The recovery of BN was greater than 94% with an intra-day relative standard deviation < or = 4.8% and an inter-day relative standard deviation < or = 14.6% at any studied level. Studies of drug stability during sample storage at -20 degrees C and at +4 degrees C did not show any significative degradation of BN. This method was successfully applied to explore the overdose state of heroin-dependent subjects treated by high-dose BN.