Simple and rapid quantification of cetirizine, venlafaxine, and O-desmethylvenlafaxine in human breast milk, and metformin in human milk and plasma with UHPLC-MS/MS.

The majority of women have health problems that require medication after giving birth. Complications such as allergies, postpartum depression, and diabetes are often treated with drugs such as cetirizine, venlafaxine, and metformin, respectively. These treatments are considered safe during lactation, but information of the transfer of drugs to breast milk and possible effects on the infant is scarce. Therefore, this needs to be systematically investigated in larger populations. To enable the determination of drug transfer, we here describe the validation of two rapid, sensitive, and high-throughput analysis methods for 1) simultaneous quantification of cetirizine, venlafaxine, and O-desmethylvenlafaxine in human breast milk, and 2) metformin in human breast milk and plasma. In both methods, a simple protein precipitation protocol with acetonitrile and benchtop-centrifugation was used prior to compound analysis with liquid-chromatography tandem mass spectrometry. The methods had linear ranges between 0.39 - 194.5 ng/mL for cetirizine, 0.28 - 138.7 ng/mL for venlafaxine, 0.26 - 131.7 ng/mL for O-desmethylvenlafaxine, in milk, and 0.65 - 193.7 ng/mL for metformin in both milk and plasma. Intra-run and inter-run precision and accuracy were ≤ 9% for cetirizine, venlafaxine, and O-desmethylvenlafaxine in milk, and ≤ 7% for metformin in milk and plasma. Cetirizine was measured to median milk concentrations of 13 ng/mL (range: 0.65 - 65 ng/mL) in 228 donor samples from breast-feeding women.