Chromatographic separation of ( E)- and ( Z)-isomers of entacapone and their simultaneous quantitation in human plasma by LC–ESI-MS/MS

• Published in: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Vol. 877; no. 5; pp. 533 - 540
• Main Authors: Yadav, Manish, Dixit, Pramod, Trivedi, Vikas, Gandhi, Abhishek, Senger, Arvind, Guttikar, Swati, Singhal, Puran, Shrivastav, Pranav S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.02.2009; Elsevier
• Subjects: ( E)-entacapone; ( Z)-entacapone; Administration, Oral; Adolescent; Adult; Analysis; Analytical, structural and metabolic biochemistry; Antiparkinson Agents - administration & dosage; Antiparkinson Agents - blood; Antiparkinson Agents - chemistry; Antiparkinson Agents - pharmacokinetics; Biological and medical sciences; Catechols - administration & dosage; Catechols - blood; Catechols - chemistry; Catechols - pharmacokinetics; Chromatographic separation; Chromatography, Liquid; Drug Stability; Fundamental and applied biological sciences. Psychology; General pharmacology; Health; High throughput; Human plasma; Humans; Isomerism; LC-ESI-MS; LC–ESI-MS/MS; Male; Medical sciences; Middle Aged; Nitriles - administration & dosage; Nitriles - blood; Nitriles - chemistry; Nitriles - pharmacokinetics; Pharmacology. Drug treatments; Spectrometry, Mass, Electrospray Ionization - methods; Tablets; High throughput; ( E)-entacapone; ( Z)-entacapone; Chromatographic separation; Human plasma; LC–ESI-MS/MS; Human; (Z)-entacapone; Biological fluid; Stereoisomer; Chemical analysis; Enzyme; Transferases; Enzyme inhibitor; Catechol O-methyltransferase; (E)-entacapone; Antiparkinson agent; Chromatography; Electrospray; Blood plasma; Methyltransferases; Simultaneous measurement; Entacapone; LC―ESI―MS/MS; Quantitative analysis
• ISSN: 1570-0232; 1873-376X
• DOI: 10.1016/j.jchromb.2009.01.004

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 500 μL of human plasma. Both the analytes were chromatographically separated with a resolution factor of 3.0 on a Gemini C18 (50 mm × 4.6 mm, 5 μm particle size) analytical column using 1% formic acid and methanol (50:50, v/v) as the mobile phase. The selectivity factor ( α) 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 24.3–6076 ng/mL and 23.8–5960 ng/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 200 mg ( E)-entacapone tablet formulation under fasting conditions.