Sensitive determination of tenofovir in human plasma samples using reversed-phase liquid chromatography.

A new high-performance liquid chromatography assay was developed for the determination of tenofovir, a nucleotide analogue, in plasma. A solid-liquid extraction procedure was coupled with a reversed-phase HPLC system. The system requires a mobile phase containing Na(2)HPO(4) buffer, tetrabutylammonium hydrogen sulfate and acetonitrile for different elution through a C(18) column with UV detection. The method proved to be accurate, precise and linear between 10 and 4000 ng/ml. The method was applied to determine trough levels of tenofovir in 11 HIV-infected patients with virologic failure under multiple antiretroviral therapy. This method was also successfully applied to a pharmacokinetic study in an HIV infected patient with renal failure.