A rapid and sensitive liquid chromatography–tandem mass spectrometric (LC–MS/MS) assay method has been developed and fully validated for the simultaneous quantification of telmisartan and amlodipine in human plasma. Carbamazepine was used as an internal standard. Analytes and the internal standard were extracted from human plasma by solid-phase extraction technique using Waters Oasis® HLB 1 cm3 (30 mg) extraction cartridge. The reconstituted samples were chromatographed on a Hypurity advance C18 column (50 mm×4.6 mm, 5 μm) using a mixture of acetonitrile–5 mM ammonium acetate buffer (pH-4.0) (50:50, v/v) as the mobile phase at a flow rate of 0.8 mL/min. The calibration curve obtained was linear (r≥0.99) over the concentration range of 2.01–400.06 ng/mL for telmisartan and 0.05–10.01 ng/mL for amlodipine. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. A run time of 2.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The proposed method was found to be applicable to clinical studies.

This paper describes a simple, rapid and sensitive liquid chromatography–tandem mass spectrometry assay for the determination of duloxetine in human plasma. A duloxetine stable labeled isotope (duloxetine d5) was used as an internal standard. Analyte and the internal standard were extracted from 100 μL of human plasma via solid phase extraction technique using Oasis HLB cartridges. The chromatographic separation was achieved on a C18 column by using a mixture of acetonitrile–5 mM ammonium acetate buffer (83:17, v/v) as the mobile phase at a flow rate of 0.9 mL/min. The calibration curve obtained was linear (r2≥0.99) over the concentration range of 0.05–101 ng/mL. Multiple-reaction monitoring mode (MRM) was used for quantification of ion transitions at m/z 298.3/154.1 and 303.3/159.1 for the drug and the internal standard, respectively. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies.

A rapid, simple, sensitive and selective LC-MS/MS method has been developed and validated for quantification of the atorvastatin (AT) and niacin (NA) in 250 μL human plasma. The analytical procedure involves a liquid-liquid extraction method using nevirapine as an internal standard (IS). The chromatographic separation was achieved on a Hypurity Advance (4.6 × 50 mm, 5 µm) column using a mobile phase consisting of 0.1% formic acid buffer-acetonitrile (20:80, v/v) at flow rate of 0.8 mL/min. The API-4000 LC-MS/MS was operated in the multiple-reaction monitoring mode using electrospray ionization. The total run time of analysis was 3 min and elution of AT, NA and IS occurred at 1.06, 1.84 and 0.92 min, respectively. A detailed validation of the method was performed as per the US Food and Drug Administration guidelines and the standard curves found to be linear in the range of 0.10-30.0 ng/mL for AT and 20.2-6026 ng/mL for NA, with a coefficient of correlation of ≥ 0.99 for both the compounds. AT and NA were found to be stable in a battery of stability studies, viz. bench-top, autosampler, re-injection, wet-extract and repeated freeze-thaw cycles. The developed assay method was successfully applied to a pharmacokinetic study in humans.

A simple, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of angiotensin-converting enzyme inhibitor, moexipril, in human plasma. Benazepril was used as an internal standard (IS). Analyte and IS were extracted from the human plasma by liquid-liquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on a C₁₈ column by using a mixture of methanol and 0.1% formic acid buffer (85:15, v/v) as the mobile phase at a flow rate of 0.5 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.2-204 ng/mL. The multiple reaction-monitoring mode was used for quantification of ion transitions at m/z 499.4/234.2 and 425.2/351.1 for moexipril and IS, respectively. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. A run time of 2.0 min for each sample made it possible to analyze more than 400 plasma samples per day. The proposed method was found to be applicable to clinical studies.

A rapid, simple, sensitive and selective LC-MS/MS method has been developed and validated for simultaneous quantification of silodosin and silodosin β-D-glucuronide human plasma using stable labelled isotopes as internal standards. Solid phase extraction technique (SPE) was used for the extraction and the method validated over a range of 0.20 ng/mL to 100.56 ng/mL for silidisin and 0.20 ng/mL to 101.63 ng/mL for silodosin β-D-glucuronide. The chromatographic separation was achieved on Cosmicsil Adze C18 (4.6 × 100 mm, 3 µm) column using a mobile phase consisting of acetonitrile, methanol and 10 mM ammonium acetate buffer 50:20:30 (v/v/v) at a flow rate of 1.000 mL/min with run time of 4 min. The API-4500 LC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. The developed assay method was successfully applied to a pharmacokinetic study in humans.