ABSTRACT
OBJECTIVE: To assess the bioequivalence of an ezetimibe/simvastatin (EZE/SIMVA) combination tablet compared to the coadministration of ezetimibe and simvastatin as separate tablets (EZE + SIMVA). METHODS: In this open-label, randomized, 2-part, 2-period crossover study, 96 healthy subjects were randomly assigned to participate in each part of the study (Part I or II), with each part consisting of 2 single-dose treatment periods separated by a 14-day washout. Part I consisted of Treatments A (EZE 10 mg + SIMVA 10 mg) and B (EZE/SIMVA 10/10 mg/mg) and Part II consisted of Treatments C (EZE 10 mg + SIMVA 80 mg) and D (EZE/SIMVA 10/80 mg/mg). Blood samples were collected up to 96 hours post-dose for determination of ezetimibe, total ezetimibe (ezetimibe + ezetimibe glucuronide), simvastatin and simvastatin acid (the most prevalent active metabolite of simvastatin) concentrations. Ezetimibe and simvastatin acid AUC(0-last) were predefined as primary endpoints and ezetimibe and simvastatin acid Cmax were secondary endpoints. Bioequivalence was achieved if 90% confidence intervals (CI) for the geometric mean ratios (GMR) (single tablet/coadministration) of AUC(0-last) and Cmax fell within prespecified bounds of (0.80, 1.25). RESULTS: The GMRs of the AUC(0-last) and Cmax for ezetimibe and simvastatin acid fell within the bioequivalence limits (0.80, 1.25). EZE/ SIMVA and EZE + SIMVA were generally well tolerated. CONCLUSIONS: The lowest and highest dosage strengths of EZE/SIMVA tablet were bioequivalent to the individual drug components administered together. Given the exact weight multiples of the EZE/SIMVA tablet and linear pharmacokinetics of simvastatin across the marketed dose range, bioequivalence of the intermediate tablet strengths (EZE/SIMVA 10/20 mg/mg and EZE/SIMVA 10/40 mg/mg) was inferred, although these dosages were not tested directly. These results indicate that the safety and efficacy profile of EZE + SIMVA coadministration therapy can be applied to treatment with the EZE/SIMVA tablet across the clinical dose range.
Subject(s)
Anticholesteremic Agents/pharmacokinetics , Azetidines/pharmacokinetics , Simvastatin/pharmacokinetics , Adolescent , Adult , Analysis of Variance , Anticholesteremic Agents/administration & dosage , Anticholesteremic Agents/adverse effects , Area Under Curve , Azetidines/administration & dosage , Azetidines/adverse effects , Cross-Over Studies , Drug Combinations , Drug Therapy, Combination , Ezetimibe , Female , Humans , Male , Middle Aged , Reference Values , Simvastatin/administration & dosage , Simvastatin/adverse effects , Tablets , Therapeutic Equivalency , Time Factors , Treatment OutcomeABSTRACT
I, 3-(2-phenethylamino)-6-methyl-1-(2-amino-6-methyl-5-methylene-c arboxamidomethylpyridinyl)-pyrazinone dihydrochloride monohydrate, is a potent, orally active thrombin inhibitor. The compound also has two metabolites which have been shown to have thrombin inhibitory activity: benzylic alcohol M3 metabolite (II) and hydroxymethylpyrazinone M7 metabolite (III). A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of I and its two metabolites in human plasma has successfully been developed. The method consists of treating 0.5 ml plasma with 2 N NaOH and extracting I, II, III and internal standard (IV) with ethyl acetate:methyl-t-butyl ether (1:3, v/v). The analytes were then back-extracted into 2% formic acid. The analytes were chromatographed by high performance liquid chromatography (HPLC) and detected by MS/MS. Positive ionization was used on a heated nebulizer probe monitoring precursor --> product ion combinations in multiple reaction monitoring mode. The linear range is 0.5-1000 nM for I and III and 0.75-1000 nM for II. Recoveries were 88, 74, 78 and 102.1% for I, II and III and the internal standard, respectively in human plasma. Intraday variation using this method was < or = 7.9% for I, < or = 9.0%, for II and < or = 9.5% for III across the standard curve range. This method exhibits good linearity and reproducibility for the three analytes.
Subject(s)
Chromatography, High Pressure Liquid/methods , Pyrazines/blood , Pyridines/blood , Thrombin/antagonists & inhibitors , Humans , Mass Spectrometry/methods , Reference Standards , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
An LC-MS-MS method and an HPLC-UV method have been developed for the assay of a novel thrombin inhibitor in human fluids. The LC-MS-MS method is developed for plasma, which usually requires maximum sensitivity. The HPLC-UV method is for urine. In both methods, analytes are extracted using liquid-liquid extraction, and analyzed by reversed-phase high-performance liquid chromatography. A tandem mass spectrometer in the multiple reaction monitoring (MRM) mode is used for detection of the analytes in the plasma method. UV is the detector for the urine method. The plasma method has a lower limit of quantitation (LOQ) of 0.1 ng/ml with a linearity range of 0.1-100 ng/ml. The urine method has an LOQ of 8.12 ng/ml (20 nM) and the linear dynamic range is 8.12-8120 ng/ml (20-20000 nM). Both methods are fast, specific and sensitive. Various validation procedures have proven that both methods are rugged, robust and reproducible. The research also suggested that, while LC-MS-MS provides superior sensitivity and selectivity for the determination of drugs and their metabolites at very low concentrations, HPLC with a conventional detector such as UV is still useful in the analysis when the sensitivity requirement is not crucial.
