Anidulafungin Levels in Breast Milk After Cessation of Treatment: A Case Report.

Background: Anidulafungin has poor oral bioavailability, with hardly any available information on how it affects breast milk, oral absorption, or gastrointestinal side effects in the infant. Case Presentation: A 40-year-old woman who recently gave birth to a healthy infant was treated for a period of 14 days for a Candida glabrata with 100 mg anidulafungin once a day. The department of clinical pharmacy was consulted to provide advice on how long the patient had to wait after ceasing anidulafungin before it was safe to start breastfeeding, with regard to preventing possible side effects of the drug to the infant, such as diarrhea or cholestasis and increase in liver enzyme values. The advice of the hospital pharmacist was pragmatic: to start breastfeeding within 2 days after the medication was discontinued based on half-time. Results: Owing to this lack of information, we measured anidulafungin concentrations in breast milk and found low levels. Conclusion: We concluded that anidulafungin is detectable in breast milk until 32 hours after anidulafungin treatment was stopped, and that no side effects were observed by the infant.

Development and validation of a liquid chromatography/tandem mass spectrometry method for the quantification of flucloxacillin and cloxacillin in microdialysis samples.

In the present study we developed and validated a liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay for the determination of flucloxacillin in human plasma and microdialysis samples and cloxacillin in microdialysis samples, using oxacillin as the internal standard for the assay. The samples were separated on a UPLC BEH C18,1.7 µm column (2.1x50mm) and analyzed by a tandem-quadrupole mass spectrometer in multiple reaction monitoring mode using an electronspray ionization interface. For flucloxacillin the method was demonstrated to be accurate and precise in the linearity range of 1-30 mg/L in plasma and 0.05-5.0 mg/L for microdialysate with a regression coefficient (r) of 0.9986 and 0.9989 in plasma and microdialysate respectively. For cloxacillin it was accurate and precise in the range of 0.1-5.0 mg/L for microdialysate with a regression coefficient of 0.9972. The method presents a high sensitivity for flucloxacillin (lower limit of quantification of 1 mg/L for plasma and 0.05 mg/L for microdialysis samples) combined with a low within- and between-day variation (<5.0% for flucloxacillin and cloxacillin in microdialysis samples and <6.5% for plasma samples of flucloxacillin). The validation experiments for the microdialysis probes showed a relative recovery of 85.5% for flucloxacillin at a flow rate of 1.0 µL/min. The results justify the use of this assay for clinical studies for measuring free unbound tissue concentrations of flucloxacillin in patients with a Staphylococcus aureus bacteremia.