Determination of isosorbide-5-mononitrate in human plasma by high-resolution gas chromatography

Determination of Isosorbide-5-Mononitrate in Human Plasma by High-Performance Liquid Chromatography-Tandem Mass Spectrometry and Its Application to a Bioequivalence Study

Isosorbide-5-mononitrate (5-ISMN), an organic nitrate vasodilator, has been widely used worldwide to prevent angina pectoris for more than two decades. A simple and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and validated for the determination of 5-ISMN in human plasma. ¹³C₆-5-ISMN is an internal standard, and 5-ISMN was extracted from human plasma (50 µL) with ethyl acetate (200 µL) by a simple liquid-liquid extraction method. The chromatographic separation was carried out on LC-20A (Shimadzu, Japan) using an analytical column ZORBAX XDB-C₁₈ (4.6 × 50 mm, 5 µm), coupled with API 4000 tandem mass spectrometers in a multiple reaction monitoring (MRM) mode. The mobile phase was composed of acetonitrile (organic phase A) and 2 mM ammonium acetate in water (aqueous phase B) with an isocratic elution of A/B = 90 : 10 (v/v). The total run time was 3.5 min with a small injection volume (5 µL). This method was fully validated in every aspect of selectivity, linearity, accuracy, precision, matrix effect, extraction recovery, and different stabilities. It was proved that the calibration standards within the 5.00-1000 ng/mL concentration range were linear. The lower limit of quantification was 5.00 ng/mL for 5-ISMN. The intrabatch and interbatch accuracy (RE) ranged from -8.8% to 7.1% with precision between 2.4% and 6.6%. The mean values of 5-ISMN extraction recovery and matrix effect were 87.0% and 102.0%, respectively. The fully validated method was successfully applied for a bioequivalence clinical trial of oral 20 mg 5-ISMN tablets in healthy Chinese subjects.

Development and validation of a chiral LC-ESI-MS/MS method for simultaneous determination of the enantiomeric metabolites isosorbide 2-mononitrate and isosorbide 5-mononitrate of isosorbide dinitrate in rat and human plasma

A specific liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) assay was developed and validated for simultaneous determination of two active metabolites of isosorbide dinitrate (ISDN), namely, isosorbide 2-mononitrate (IS 2-MN) and isosorbide 5-mononitrate (IS 5-MN). A simple protein precipitation extraction technique was employed using ¹³C₆ isosorbide 5-mononitrate as the internal standard. The two isomers were separated on a chiral column and mass detection was carried out by electrospray ionization (ESI) in negative multiple reaction monitoring (MRM) mode (ESI -ve). As neutral organic nitrates do not ionize well in ESI ion source, adduct formation of IS 2-MN and IS 5-MN were evaluated. Acetate adduct ions of IS 2-MN and IS 5-MN were well ionized and fragmentable in the negative mode by liquid chromatography electrospray ionization/tandem mass spectrometry. These acetates adduct ions, of IS 2-MN and IS 5-MN were selected as parent mass for quantitation. The method was developed and validated in rat and human plasma with K₂EDTA as an anticoagulant. This simultaneous quantitation method was shown to be linear over a working range of 25.0 ng/mL to 5050 ng/mL and 12.4 ng/mL to 2500 ng/mL for IS 2-MN (r² > 0.99) and IS 5-MN (r² > 0.99), respectively, in rat and human plasma. Sensitivity was determined as 25.0 ng/mL for IS 2-MN and 12.4 ng/mL for IS 5-MN in rat and human plasma. Inter- and intra-day accuracy and precision were within ±15% in both method validations. This validated method was subsequently applied to a pharmacokinetic (PK) study of ISDN in rat after oral administration.

High performance liquid chromatography–electrospray ionization mass spectrometric determination of isosorbide 5-mononitrate in human plasma

A novel, selective and sensitive high performance liquid chromatography-mass spectrometric (HPLC-MS) method has been developed for the determination of isosorbide 5-mononitrate (5-ISMN) in human plasma. With acetaminophen as internal standard, sample pretreatment involved one-step extraction with diethyl ether of 0.5 mL plasma. Analysis was performed on an ACQUITY UPLC BEH C(18) column (100 mm x 2.1mm, 1.7 microm) with mobile phase consisting of acetonitrile-water (20:80, v/v). The detection was carried out by means of electrospray ionization mass spectrometry in negative ion mode with selected ion recording (SIR). Standard curves were linear (r(2)> or =0.99) over the concentration range of 1.04-1040 ng/mL. The lower limit of quantification (LLOQ) was 1.04 ng/mL. The intra- and inter-day precisions (RSDs) were less than 8.6% and 13.4%, respectively, and the accuracy (RE) was within +/-0.45%. The method herein described was fully validated and successfully applied to the pharmacokinetic study of 5-ISMN in compound extended-release tablets in 18 healthy male volunteers after oral administration.

An extensive study on isosorbide-5-mononitrate acid adducts for quantification in human plasma using liquid chromatography/electrospray ionization tandem mass spectrometry and its application to bioequivalence sample analysis

A rapid and sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for the determination of isosorbide-5-mononitrate (5-ISMN), used in the treatment of angina pectoris, in human plasma is described. The quantification of 5-ISMN was performed via stable acetate adduct formation with a high relative abundance. The plasma filtrate obtained after solid-phase extraction (SPE), using a polymer based, hydrophilic-lipophilic balanced (HLB) cartridge, was submitted directly to reversed-phase high-performance liquid chromatography separation followed by ESI and detection of the resulting ions using triple-quadrupole mass spectrometry in selected reaction monitoring (SRM) mode. There was no significant matrix effect on the analysis. For validation of the method, the recovery of the free analyte response was compared to that obtained from an optimized extraction method. The analyte stability was examined under conditions mimicking the sample storage, handling, and analytical procedures. The extraction procedure yielded extremely clean extracts with a recovery of 95.51% and 93.98% for iossorbide-5-mononitrate and topiramate (internal standard (IS)), respectively. The calibration curves were linear for the dynamic range of 10.0 to 1000.0 ng/mL with a correlation coefficient r > or = 0.9985. The intra-assay and inter-assay precision for the samples at the lower limit of quantification (LLOQ) were 9.02 and 13.30%, respectively. The intra-assay accuracies at LLOQ, LQC, MQC and HQC levels varied from 98.13 to 118.15, 102.34 to 105.21, 100.69 to 109.68, and 95.76 to 102.92%, respectively, while the inter-assay accuracies ranged from 93.10 to 118.15, 93.03 to 107.04, 86.97 to 109.68 and 86.18 to 105.85%, respectively, at these levels. The method is rugged and fast with a total run time of 2 min. The method was successfully applied for a bioequivalence study in 24 human subject samples after oral administration of 60 mg extended release (ER) formulations.