Simultaneous determination of telmisartan and amlodipine in human plasma by LC-MS/MS and its application in a human pharmacokinetic study

Abstract

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.

Keywords: Amlodipine; Human plasma; LC–MS/MS; Pharmacokinetics; Solid-phase extraction; Telmisartan.

Figure 1

Chemical structures of telmisartan (A), amlodipine (B), and carbamazepine (C).

Figure 2

Typical MRM chromatograms of telmisartan (left panel) and the IS (right panel) in human blank plasma (A), and human plasma spiked with IS (B), a LLOQ sample along with IS (C).

Figure 3

Typical MRM chromatograms of amlodipine (left panel) and the IS (right panel) in human blank plasma (A), and human plasma spiked with IS (B), a LLOQ sample along with IS (C).

Figure 4

Mean plasma concentration–time profile of telmisartan (A), and amlodipine (B), in human plasma following the oral administration of 80/10 mg fixed dose combination of telmisartan and amlodipine tablet to healthy volunteers (n=6).