title: Incurred sample reanalysis of fingolimod and fingolimod phosphate in blood: stability evaluation and application to a rat pharmacokinetic study.
abstract: BACKGROUND
  Incurred sample reanalysis (ISR) is an in-study validation parameter, which reinforces that the validated bioanalytical methods are reproducible. ISR of whole blood samples is complex when the test compounds can interconvert, ex vivo. Fingolimod and fingolimod phosphate are highly distributed in the blood cellular components and undergo rapid interconversion, both in vivo and ex vivo. An LC-MS/MS method capable of simultaneous quantification of fingolimod and fingolimod phosphate with the controlled sample preparation procedure is essential.
  
  
  RESULTS
  The ex vivo analyte interconversion in blood was controlled by lysing the blood cells.
  
  
  CONCLUSIONS
  Lysis of blood samples not only controlled the interconversion but also rendered homogeneity to the sample, which led to acceptable ISR results from the study.
authors.affiliation: Biopharmaceutical Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India.
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Nirogi
authors.affiliation: Biopharmaceutical Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India.
authors.forename: Nagasurya Prakash
authors.initials: NP
authors.lastname: Padala
authors.affiliation: Biopharmaceutical Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India.
authors.forename: Devender Reddy
authors.initials: DR
authors.lastname: Ajjala
authors.affiliation: Biopharmaceutical Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India.
authors.forename: Rajesh Kumar
authors.initials: RK
authors.lastname: Boggavarapu
authors.affiliation: Biopharmaceutical Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India.
authors.forename: Praveen
authors.initials: P
authors.lastname: Kunduru
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D000068876:Fingolimod Hydrochloride / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D010710:Phosphates / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D051381:Rats; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014018:Tissue Distribution
chemical_list: D007166:Immunosuppressive Agents; D010710:Phosphates; D000068876:Fingolimod Hydrochloride
keywords: fingolimod; fingolimod phosphate; incurred sample reanalysis; lipid phosphate phosphatase; lysis; phosphorylation and dephosphorylation; sphingosine kinase; whole blood