A New Method to Quantify Ifosfamide Blood Levels Using Dried Blood Spots and UPLC-MS/MS in Paediatric Patients with Embryonic Solid Tumours

作者：Torres Luz Maria; Rivera Espinosa Liliana; Chavez Pacheco Juan L^*; Navas Carlos F; Demetrio Joel A; Alemon Medina Radames; Trujillo Francisca; Perez Martin; Zapata Martha M; Cardenas Rocio; Salinas Citlaltepetl; Aquino Arnoldo; Velazquez Cruz Rafael; Castillejos Manuel de Jesus

来源：PLos One, 2015, 10(11): e0143421.

DOI：10.1371/journal.pone.0143421

Ifosfamide blood concentrations are necessary to monitor its therapeutic response, avoiding any adverse effect. We developed and validated an analytical method by UPLC-MS/MS to quantify ifosfamide in dried blood spots (DBS). Blood samples were collected on Whatman 9031 (R) filter paper cards. Five 3 mm disks were punched out from each dried blood spot. Acetonitrile and ethyl acetate were used for drug extraction. Chromatographic separation was carried out in an Acquity UPLC equipment with a BEH-C18 column, 2.1 x 100 mm, 1.7 mu m (Waters (R)). The mobile phase consisted in 5 mM ammonium formate and methanol: acetonitrile (40:48:12 v/v/v) at 0.2 mL/min. LC-MS/MS detection was done by ESI+ and multiple reaction mode monitoring, ionic transitions were m/z(1+) 260.99 > 91.63 for ifosfamide and 261.00 > 139.90 for cyclophosphamide (internal standard). This method was linear within a 100-10000 ng/mL range and it was accurate, precise and selective. Ifosfamide samples in DBS were stable for up to 52 days at -80 degrees C. The procedure was tested in 14 patients, ages 1 month to 17 years (9 males and 5 females), with embryonic tumours treated with ifosfamide, alone or combined, at a public tertiary referral hospital. Ifosfamide blood levels ranged from 11.1 to 39.7 mu mol/L at 12 hours after the last infusion, while 24-hour levels ranged from 0.7-19.7 mu mol/L. The median at 12 hours was 19.5 mu mol/L (Q(25) 14.4-Q(75) 29.0) and 3.8 mu mol/L (Q(25) 1.5-Q(75) 9.9) at 24 hours, p<0.001. This method is feasible to determine ifosfamide plasma levels in paediatric patients.

• 出版日期2015-11-23