Development and validation of a high-performance liquid chromatography–tandem mass spectrometry assay quantifying olaparib in human plasma

• This assay was fully validated according to the latest FDA and EMA guidelines.
• Liquid–liquid extraction was used as sample pretreatment with a deuterated isotope as internal standard.
• This assay is considered very suitable to support clinical pharmacologic studies of olaparib.

Olaparib is an inhibitor of poly ADP ribose polymerase 1 (PARP-1). Phase I and II trials showed promising results of olaparib against tumours in BRCA mutation carriers. Currently an increasing number of clinical trials with olaparib in combination with other compounds or radiotherapy are conducted. To support these clinical trials an LC–MS/MS method was developed and validated for the quantification of olaparib in human plasma. Human plasma samples were collected in the clinic and stored at nominally −20 °C. Olaparib was isolated from plasma by liquid–liquid extraction, separated on a C18 column with gradient elution and analyzed with triple quadrupole mass spectrometry in positive ion mode. A deuterated isotope was used as internal standard for the quantification. The assay, ranging from 10 to 5000 ng/mL, was linear with correlation coefficients (r2) of 0.9994 or better. The assay was accurate and precise, with inter-assay and intra-assay accuracies within ±7.6% of nominal and inter-assay and intra-assay precision ≤9.3% at the lower limit of quantification and ≤5.7% at the other concentration levels tested. All results were within the acceptance criteria of the US FDA and the latest EMA guidelines for method validation. A quantitative method was developed and validated for the quantification of olaparib in human plasma. The method could successfully be applied for the pharmacokinetic quantification of olaparib in cancer patients treated with olaparib.