title: Chromatographic separation of (E)- and (Z)-isomers of entacapone and their simultaneous quantitation in human plasma by LC-ESI-MS/MS.
abstract: A selective, sensitive and high throughput liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) method has been developed and validated for the chromatographic separation and quantitation of (E)-entacapone and (Z)-entacapone in human plasma. Sample clean-up involved liquid-liquid extraction (LLE) of both the isomers and carbamazepine used as internal standard from 500microL of human plasma. Both the analytes were chromatographically separated with a resolution factor of 3.0 on a Gemini C18 (50mmx4.6mm, 5microm particle size) analytical column using 1% formic acid and methanol (50:50, v/v) as the mobile phase. The selectivity factor (alpha) of the column for the separation was 2.0, based on the capacity factors of 2.6 and 1.3 for (E)- and (Z)-isomers respectively. The parent-->product ion transitions for both the isomers (m/z 306.1-->233.0) and IS (m/z 237.3-->194.2) were monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring (MRM) and positive ion mode. The method was validated over the concentration range of 24.3-6076ng/mL and 23.8-5960ng/mL for (E)-entacapone and (Z)-entacapone respectively. Matrix effect was assessed by post-column analyte infusion experiment and the process/extraction efficiency found was 94.3% and 89.3% for (E)- and (Z)-isomers respectively. The method was successfully applied to a pivotal bioequivalence study in 36 healthy human subjects after oral administration of 200mg (E)-entacapone tablet formulation under fasting conditions.
authors.affiliation: Bioanalytical Research Department, Veeda Clinical Research, Ambawadi, Ahmedabad 3800015, Gujarat, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Yadav
authors.forename: Pramod
authors.initials: P
authors.lastname: Dixit
authors.forename: Vikas
authors.initials: V
authors.lastname: Trivedi
authors.forename: Abhishek
authors.initials: A
authors.lastname: Gandhi
authors.forename: Arvind
authors.initials: A
authors.lastname: Senger
authors.forename: Swati
authors.initials: S
authors.lastname: Guttikar
authors.forename: Puran
authors.initials: P
authors.lastname: Singhal
authors.forename: Pranav S
authors.initials: PS
authors.lastname: Shrivastav
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000978:Antiparkinson Agents / Q000008:administration & dosage / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics; D002396:Catechols / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry* / Q000493:pharmacokinetics; D002853:Chromatography, Liquid; D004355:Drug Stability; D006262:Health; D006801:Humans; D007536:Isomerism; D008297:Male; D008875:Middle Aged; D009570:Nitriles / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry* / Q000493:pharmacokinetics; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013607:Tablets
chemical_list: D000978:Antiparkinson Agents; D002396:Catechols; D009570:Nitriles; D013607:Tablets; C071192:entacapone