Validation and implementation of an ultrasensitive liquid chromatographic-tandem mass spectrometric (LC-MS/MS) assay for dapivirine quantitation in breast milk

Background: The non-nucleoside reverse transcriptase inhibitor dapivirine has been evaluated as a topical microbicidal agent to prevent HIV-1 acquisition. Several clinical trials have evaluated the pharmacokinetics of dapivirine when administered as a 25-mg intravaginal ring. Recent studies have focused on the distribution of dapivirine into breast milk. Drug distribution during lactation and breastfeeding can have implications in terms of infant drug exposure. Thus, sensitive bioanalytical tools are required to characterize the pharmacokinetics of dapivirine in breast milk. Methods: Whole breast milk was spiked with dapivirine and internal standard. Lipid content was disrupted via pre-treatment with n-hexane, and supernatants were subjected to solid phase extraction. Extracted materials were subjected to liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis. Separation occurred using a Waters BEH C8, 50 × 2.1 mm UPLC column with a 1.7 µm particle size and dapivirine was detected on an API 5000 mass analyzer. Methods were validated in accordance with FDA Bioanalytical Method Validation recommendations. Results: The analytical method was optimized for dapivirine extraction from breast milk. The analytical measuring range of the assay was 10–1000 pg/mL. Calibration curves were generated via weighted linear regression of standards. Intra- and inter-assay precision and accuracy studies demonstrated %CVs ≤ 14.6% and %DEVs ≤ ±12.7%. Stability and matrix effects studies were also conducted and deemed acceptable. The method was applied to a previously reported phase 1 clinical trial and demonstrated appropriate performance in the quantitation of dapivirine in breast milk samples from lactating women. Conclusions: An ultrasensitive LC-MS/MS assay has been developed and validated for the quantitation of dapivirine in breast milk. The described method meets validation acceptance criteria and has been applied to a phase 1 clinical trial.