Determination of enalapril and enalaprilat in small human serum quantities for pediatric trials by HPLC-tandem mass spectrometry.

The angiotensin converting enzyme-inhibitor enalapril is the prodrug of enalaprilat and used in the treatment pediatric hypertension and chronic heart failure. Pharmacokinetic data are lacking to provide adequate dosing and for pediatric pharmacotherapeutical trials it is imperative to minimize sample volume. Therefore an HPLC-tandem mass spectrometry (MS) method for the determination of enalapril and enalaprilat in 100 μL of human serum was developed and validated with benazepril as internal standard (IS). After solid-phase extraction, chromatography was performed on a Luna(®) RP-C(18) (2) column with methanol-water-formic acid (65:35:1, v/v/v) as mobile phase and a flow rate of 0.4 mL/min. The MS was set to positive-mode electrospray ionization and multiple reaction monitoring, analyzing the m/z transitions channels 377.3 → 234.2, 349.3 → 206.1 and 425.3 → 351.2 for enalapril, enalaprilat and IS. Calibration curves were linear in the range of 1.61-206 ng/mL (enalapril) and 1.84-236 ng/mL (enalaprilat) with coefficients of determination >0.99. Relative standard deviations of intra- and inter-run precisions were below 7% and relative errors were below 6 ± 7% for both analytes. Also stabilities were acceptable for both analytes. As an application example, concentrations of enalapril and enalaprilat in serum after oral administration of 20 mg enalapril maleat in a healthy volunteer were determined.

Ramusovic S ，Thielking G ，Läer S 《-》

Simultaneous quantification of enalapril and enalaprilat in human plasma by high-performance liquid chromatography-tandem mass spectrometry and its application in a pharmacokinetic study.

Lu S ，Jiang K ，Qin F ，Lu X ，Li F ... -  《JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS》

Simultaneous quantitation of enalapril and enalaprilat in human plasma by 96-well solid-phase extraction and liquid chromatography/tandem mass spectrometry.

A sensitive and rapid method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) combined with rapid solid-phase extraction (SPE) has been developed and validated for the quantitative determination of enalapril and its active metabolite enalaprilat in human plasma. After addition of internal standard to human plasma, samples were extracted by 96-well SPE cartridge. The extracts were analyzed by HPLC with the detection of the analyte in the multiple reaction monitoring (MRM) mode. This method for the simultaneous determination of enalapril and enalaprilat was accurate and reproducible, with respective limits of quantitation of 0.2 and 1.0 ng/mL in plasma. The standard calibration curves for both enalapril and enalaprilat were linear (r(2) = 0.9978 and 0.9998) over the concentration ranges 0.2-200 and 1.0-100 ng/mL in human plasma, respectively. The intra- and inter-day precision over the concentration range for enalapril and enalaprilat were lower than 13.3 and 15.4% (relative standard deviation, %RSD), and accuracy was between 89.2-105.0 and 91.9-104.7%, respectively.

Lee J ，Son J ，Lee M ，Lee KT ，Kim DH ... -  《RAPID COMMUNICATIONS IN MASS SPECTROMETRY》

Simultaneous determination of enalapril and enalaprilat in human plasma by liquid chromatography-tandem mass spectrometry.

Gu Q ，Chen X ，Zhong D ，Wang Y ... -  《JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES》

Simultaneous quantitative and qualitative analysis of aliskiren, enalapril and its active metabolite enalaprilat in undiluted human urine utilizing LC-ESI-MS/MS.

The benefit-risk ratio of combined blocking by the direct renin inhibitor aliskiren and an angiotensin-converting enzyme inhibitor (e.g. enalapril) on the renin-angiotensin-aldosterone system is discussed. No method was available for simultaneous determination of both drugs in urine. A novel sensitive method for simultaneous quantification in undiluted human urine was developed which enables systematic pharmacokinetic investigations, especially in poorly investigated populations like children. Matrix effects were clearly reduced by applying solid-phase extraction followed by a chromatographic separation on Xselect(TM) C18 CSH columns. Mobile phase consisted of methanol and water, both acidified with formic acid. Under gradient conditions and a flow rate of 0.4 mL/min the column effluent was monitored by tandem mass spectrometry with electrospray ionization. Calibration curves were constructed in the range of 9.4-9600 ng/mL regarding aliskiren, 11.6-12000 ng/mL for enalapril and 8.8-9000 ng/mL for enalaprilat. All curves were analyzed utilizing 1/x(2) -weighted quadratic squared regression. Intra-run and inter-run precision were 3.2-5.8% and 6.1-10.3% for aliskiren, 2.4-6.1% and 3.9-7.9% for enalapril as well as 3.1-9.4% and 4.7-12.7% regarding enalaprilat. Selectivity, accuracy and stability results comply with current international bioanalysis guidelines. The fully validated method was successfully applied to a pharmacokinetic investigation in healthy volunteers.

Burckhardt BB ，Tins J ，Laeer S 《-》