“…Intracellular Leishmania parasites reside and survive in macrophages; therefore, quantifying miltefosine intracellularly directly provides the exposure in concentration of Leishmania to miltefosine (Kip et al, 2015). The validated calibration model ranges of the bioanalytical methods for miltefosine were 300–2500 ng/ml (Lemke & Kayser, 2006), 2.5–400 ng/ml (Jaiswal et al, 2016), 4–1000 ng/ml (Roseboom, Thijssen, Rosing, Alves, Mondal, et al, 2022), and 4–2000 ng/ml (Dorlo, Hillebrand, et al, 2008; Kip et al, 2015, 2016, 2017; Roy et al, 2015). The range of 2.5–400 ng/ml was the most sensitive bioanalytical assay for miltefosine using MS/MS, although showing a low sample preparation volume of 50 μl (Jaiswal et al, 2016).…”