title: Determination of apremilast in rat plasma by UPLC-MS/MS in ESI-negative mode to avoid adduct ions formation.
abstract: Quantification of target analyte by LC-MS/MS is sometimes hampering due to competitive adduct ions formation (sodium and/or ammonium) in positive ionization mode. A UPLC-MS/MS assay was developed for the determination of apremilast in rat plasma using ESI-negative mode to avoid adduct ions formation.
  
  
  
  After extraction from plasma by ethyl acetate, analyte and IS were separated on Aquity BEH C18column using acetonitrile-10 mM ammonium acetate (85:15) as mobile phase. The calibration curve was linear between 3.04 and 1000 ng/ml with correlation coefficients (r2) of ≥0.995 and lower limit of quantification of 3.04 ng/ml. All validation parameter results were within the acceptable range. The assay was successfully employed in oral PK study with Cmaxof 584.29 ng/ml and AUC0-20of 6530 ng.h/ml after apremilast (2 mg/kg) administration.
  
  
  
  This result suggests that ESI in negative mode would be an alternative approach for LC-MS/MS quantification of analytes, which produce competitive adducts in positive mode.
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh, 11451, KSA.|Bioavailability Laboratory, College of Pharmacy, King Saud University, Riyadh, 11451, KSA.
authors.forename: Muzaffar
authors.initials: M
authors.lastname: Iqbal
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh, 11451, KSA.|Bioavailability Laboratory, College of Pharmacy, King Saud University, Riyadh, 11451, KSA.
authors.forename: Essam
authors.initials: E
authors.lastname: Ezzeldin
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh, 11451, KSA.
authors.forename: Sara Ta
authors.initials: ST
authors.lastname: Al-Rashood
authors.affiliation: Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, KSA.
authors.forename: Faisal
authors.initials: F
authors.lastname: Imam
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh, 11451, KSA.
authors.forename: Khalid A
authors.initials: KA
authors.lastname: Al-Rashood
keywords: PK; UPLC–MS/MS; adduct ions; apremilast; negative ionization mode; plasma; rats