title: A simple and sensitive LC/MS/MS assay for 7-ethyl-10-hydroxycamptothecin (SN-38) in mouse plasma and tissues: application to pharmacokinetic study of liposome entrapped SN-38 (LE-SN38).
abstract: An LC/MS/MS method to quantify SN-38 in mouse plasma and tissue homogenates containing liposome entrapped SN-38 (LE-SN38) was developed. Camptothecin (CPT) was used as the internal standard (IS). Sample preparation consisted of simple protein precipitation by acetonitrile containing 0.5% acetic acid. SN-38 and IS were separated by a C18 HPLC column and detected using a mass spectrometer operating in the multiple reaction monitoring (MRM) mode. The peak area of the m/z 393.3-->349.1 transition of SN-38 and that of the m/z 349.1-->305.2 transition of the IS were measured and a standard curve was generated from their ratios. The method had a LLOQ of 0.5 ng/mL in mouse plasma, which corresponds to 2.5 pg for the 5 microL injection volume. The linear range was 0.5-1000 ng/mL of SN-38 in plasma sample spiked with LE-SN38. The LLOQ in tissue homogenates (5%, w/v) quantitation was 1 ng/mL (20 ng/g tissue) of SN-38 in kidney, liver, lung, and spleen homogenates, and 2 ng/mL (40 ng/g tissue) in heart homogenate containing LE-SN38. The assay was linear up to 400 ng/mL of SN-38 in tissue homogenates, and may be extended to 120 microg/mL by proper dilution of samples over the upper limit of quantitation. Acceptable precision and accuracy were obtained for concentrations over the entire standard curve range, both between-run and within-run for plasma and tissue homogenates. The method was successfully used to quantify SN-38 in plasma and tissues samples for pharmacokinetic and tissue distribution studies of LE-SN38 in mice.
authors.affiliation: Pharmacokinetics, Safety and Efficacy Department, Research and Development, NeoPharm, Inc., Waukegan, IL 60085, USA.
authors.forename: Sumsullah
authors.initials: S
authors.lastname: Khan
authors.forename: Ateeq
authors.initials: A
authors.lastname: Ahmad
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.forename: Yue-Fen
authors.initials: YF
authors.lastname: Wang
authors.forename: Aqel
authors.initials: A
authors.lastname: Abu-Qare
authors.forename: Imran
authors.initials: I
authors.lastname: Ahmad
mesh_terms: D000818:Animals; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000097:blood* / Q000493:pharmacokinetics*; D002853:Chromatography, Liquid / Q000379:methods; D000077146:Irinotecan; D008081:Liposomes; D013058:Mass Spectrometry / Q000379:methods; D051379:Mice; D014018:Tissue Distribution / Q000187:drug effects / Q000502:physiology
chemical_list: D008081:Liposomes; D000077146:Irinotecan; D002166:Camptothecin