Quantitative determination of fluvastatin in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry using [18O2]-fluvastatin as an internal standard

High resolution mass spectrometry based method applicable for a wide range of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors in blood serum including intermediates and products of the cholesterol biosynthetic pathway

Statins belong to the major class of hypolipidemic drugs. They act as competitive inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, a rate-limiting enzyme in the cholesterol biosynthetic pathway. This inhibition not only leads to the depletion of cholesterol and its fatty acid esters, but also to the depletion of the intermediates of this metabolic pathway (mainly pyrophosphates), which can play an important role in tumor proliferation. The aim of the current study was to establish a versatile multi-analyte method capable of quantitative determination of various currently-used statins, together with free cholesterol (FC), cholesterol esters (CEs), and some key intermediates of the mevalonate pathway occurring in human serum. Various methods of sample preparation were examined in order to minimize the content of potentially interfering serum proteins, and simultaneously to assure acceptable recovery of the target analytes. Following protein precipitation with 2-propanol, separation of the sample components using ultra-high performance liquid chromatography coupled with tandem high resolution mass spectrometry (U-HPLC-HRMS/MS) was performed, employing a hyphenated quadrupole Orbitrap mass analyzer. The potential of the developed method was validated on human serum samples from patients treated with statins. This versatile method possesses wide applicability, in both clinical and experimental medicine.

Preparation of a highly specific polyclonal antibody against and its use in development of ELISA for determination of in plasma

For therapeutic monitoring and pharmacokinetic studies of the potent hypocholesterolaemic agent fluvastatin (FLV), a specific antibody was required for the development of a sensitive enzyme-linked immunosorbent assay (ELISA) for the accurate determination of FLV in plasma. In this study, a highly specific polyclonal antibody against FLV has been prepared. FLV was coupled to keyhole limpet hemocyanin (KLH) and bovine serum albumin (BSA) using carbodiimide reagent. FLV-KLH conjugate was used as an immunogen. Female 8-weeks old New Zealand white rabbits were immunized with an emulsion of FLV-KLH with Freund's adjuvant. The immune response of the rabbits was monitored by direct ELISA using FLV-BSA immobilized onto microwell plates as a solid phase. The rabbit that showed the highest antibody titer and affinity to FLV was scarified and its sera were collected. The IgG fraction was isolated and purified by affinity chromatography on a protein A column. The specificity of the purified antibody for FLV was evaluated by indirect competitive ELISA using various competitors from the FLV-structural analogues and therapeutic agents used with FLV in a combination therapy. The high affinity of the antibody (IC50 = 150 pg ml-1) enabled the determination of FLV in plasma at concentrations as low as 20 pg ml-1.

Chromatography–mass spectrometry methods for the quantitation of statins in biological samples

The 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors, more commonly known as 'statins', are a novel class of drugs widely used for the treatment of hypercholesterolaemia in patients with established cardiovascular disease as well as those at high risk of developing atherosclerosis. Published chromatographic-mass spectrometric methods for the quantification of presently available seven statins, atorvastatin, simvastatin, lovastatin, pravastatin, fluvastatin, rosuvastatin and pitavastatin are reviewed. High performance liquid chromatography (HPLC) in combination with tandem mass spectrometry (MS/MS) is the analytical technique of choice for the quantification of statins in biological samples. This review envisages that most of the methods used for quantification of statins are in plasma and they are suitable for therapeutic drug monitoring of these drugs.

Liquid chromatography/negative ion electrospray tandem mass spectrometry method for the quantification of fluvastatin in human plasma: validation and its application to pharmacokinetic studies

A simple, sensitive and rapid high-performance liquid chromatography/negative ion electrospray tandem mass spectrometry method was developed and validated for the assay of fluvastatin in human plasma. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 410/348 for fluvastatin and m/z 480/418 for the internal standard. The assay exhibited a linear dynamic range of 2-500 ng/mL for fluvastatin in human plasma. The lower limit of quantification was 2 ng/mL with a relative standard deviation of less than 5%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 1.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.