title: Quantitation of 4-cyclohexyl-2-hydroxy-3-(3-methylsulfanyl-2- [2-[(morpholine-4-carbonyl)amino]-3-phenylpropionylamino]propi onylamino ) butyric acid isopropyl ester (CP-80,794), a renin inhibitor, and its hydrolytic cleavage metabolite 2-[(morpholine-4-carbonyl)amino]-3-phenylpropionic acid (CP-84,364) in dog and human plasma by high-performance liquid chromatography.
abstract: Simple and precise high-performance liquid chromatographic (HPLC) assays were developed and validated for the determination of a renin inhibitor (RI), 4-cyclohexyl-2-hydroxy-3- (3-methylsulfanyl-2-[2-[(morpholine-4-carbonyl)amino]- 3-phenylpropionylamino]propionylamino)butyric acid isopropyl ester (CP-80,794, I), and its hydrolytic cleavage metabolite, 2-[(morpholine-4-carbonyl)amino]-3-phenylpropionic acid (CP-84,364, II) in dog and human plasma. The internal standard for I, CP-83,092 (III, a carbon-substituted derivative of I) and analyte were extracted by liquid-liquid extraction using n-butyl chloride, cleaved to form a fragment containing a primary amine, and subsequently fluorescently derivatized for measurement by HPLC. Samples were analyzed by reversed-phase HPLC using a Waters C18 column with fluorescence detection at 390 nm excitation/440 nm emission. The quantitation limit of I was 10 ng/ml and the calibration curve was linear over the range of 0.01-1.0 microgram/ml (r2 > 0.99). In dog and human plasma, intra- and inter-assay precision ranged from 2.3 to 16% and 3.0 to 18%, respectively. The average recoveries were similar (> or = 63%) for both I and III and the upper limit of quantification of I can be as high as 4 micrograms/ml. The internal standard for II, CP-96,452 (IV, a methoxy derivative of II) and analyte were extracted by anion-exchange solid-phase extraction and subsequent liquid-liquid extraction using methyl tert.-butyl ether. Samples were analyzed by reversed-phase HPLC using a Waters C18 column with ultraviolet detection at 214 nm. The quantitation limit of II was 20 ng/ml and the calibration curve was linear over the range of 0.02-2.0 micrograms/ml (r2 > 0.99). In dog and human plasma, intra- and inter-assay precision ranged from 2.6 to 13.0% and 1.8 to 20.0%, respectively. The average recoveries were similar (> or = 75%) for both II and IV and the upper limit of quantification of II can be as high as 20 micrograms/ml. The methods described have been successfully applied to the quantification of I and II in about 5000 dog and human plasma samples over a 2 year period.
authors.affiliation: Drug Metabolism Department, Pfizer Inc., Groton, CT 06340, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Allen
authors.forename: C G
authors.initials: CG
authors.lastname: Stafford
authors.forename: M R
authors.initials: MR
authors.lastname: Nocerini
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004151:Dipeptides / Q000097:blood*; D004285:Dogs; D006801:Humans; D009025:Morpholines / Q000097:blood*; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000097:blood; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D000092502:Renin Inhibitors
chemical_list: D004151:Dipeptides; D009025:Morpholines; D010649:Phenylalanine; D000092502:Renin Inhibitors; C108797:CP 84364; C076964:terlakiren