High-performance liquid chromatography coupled with negative ion tandem mass spectrometry for determination of pravastatin in human plasma

UHPLC-MS/MS assay for simultaneous determination of amlodipine, metoprolol, pravastatin, rosuvastatin, atorvastatin with its active metabolites in human plasma, for population-scale drug-drug interactions studies in people living with HIV

Thanks to highly active antiretroviral treatments, HIV infection is now considered as a chronic condition. Consequently, people living with HIV (PLWH) live longer and encounter more age-related chronic co-morbidities, notably cardiovascular diseases, leading to polypharmacy. As the management of drug-drug interactions (DDIs) constitutes a key aspect of the care of PLWH, the magnitude of pharmacokinetic DDIs between cardiovascular and anti-HIV drugs needs to be more thoroughly characterized. To that endeavour, an UHPLC-MS/MS bioanalytical method has been developed for the simultaneous determination in human plasma of amlodipine, metoprolol, pravastatin, rosuvastatin, atorvastatin and its active metabolites. Plasma samples were subjected to protein precipitation with methanol, followed by evaporation at room temperature under nitrogen of the supernatant, allowing to attain measurable plasma concentrations down to sub-nanogram per milliliter levels. Stable isotope-labelled analytes were used as internal standards. The five drugs and two metabolites were analyzed using a 6-min liquid chromatographic run coupled to electrospray triple quadrupole mass spectrometry detection. The method was validated over the clinically relevant concentrations ranging from 0.3 to 480 ng/mL for amlodipine, atorvastatin and p-OH-atorvastatin, and 0.4 to 480 ng/mL for pravastatin, 0.5 to 480 ng/mL for rosuvastatin and o-OH-atorvastatin, and 3 to 4800 ng/mL for metoprolol. Validation performances such as trueness (95.4-110.8%), repeatability (1.5-13.4%) and intermediate precision (3.6-14.5%) were in agreement with current international recommendations. Accuracy profiles (total error approach) were lying within the limits of ±30% accepted in bioanalysis. This rapid and robust UHPLC-MS/MS assay allows the simultaneous quantification in plasma of the major currently used cardiovascular drugs and offers an efficient analytical tool for clinical pharmacokinetics as well as DDIs studies.

Quantification of pravastatin acid, lactone and isomers in human plasma by UHPLC-MS/MS and its application to a pediatric pharmacokinetic study

An ultra high pressure liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) method for the simultaneous quantitation of pravastatin and major metabolites, 3'α-hydroxy-pravastatin, pravalactone and 3'α-hydroxy-pravalactone, in human plasma has been developed and validated. Aliquots of (100μL) plasma in EDTA were diluted in pH 4.5 (0.1M buffer) to stabilize the analytes and subjected to hydrophilic lipophilic balance (HLB) solid phase extraction on 96 well μelution plates. Extracted samples were evaporated to dryness and reconstituted in pH 4.5 buffer. Chromatographic separation was performed on a Cortecs™ C18 column (2.1×100mm, 1.8μm), using gradient elution with a blend of acetonitrile and 10mM methylammonium acetate buffer (pH 4.5) at a flow rate of 0.4mL/min. Mass spectrometric detection was performed using multiple reaction monitoring (MRM) switching between positive/negative electrospay ionization (ESI). Pravastatin, 3'α-hydroxy-pravastatin, and internal standards [(2)H3]-pravastatin, and [(2)H3]-3'α-hydroxy-pravastatin were monitored in negative ESI mode at ion transitions m/z 423.2→321.1 and 426.2→321.1, respectively. Positive ESI mode was used for the detection of pravalactone, 3'α-hydroxy-pravalactone, and internal standards [(2)H3]-pravalactone, and [(2)H3]-3'α-hydroxy-pravalactone at ion transitions m/z 438.2→183.1 and 441.2→269.1 respectively. The method was linear for all analytes in the concentration range 0.5-200nM with intra- and inter-day precisions (as relative standard deviation) of ≤5.2% and accuracy (as relative error) of ≤8.0% at all quality control levels. The method was successfully applied to the investigation of pharmacokinetic properties of pravastatin and its metabolites in children after an oral dose of 20-40mg.

Quantitative determination of pravastatin and its metabolite 3α-hydroxy pravastatin in plasma and urine of pregnant patients by LC-MS/MS

This report describes the development and validation of a chromatography/tandem mass spectrometry method for the quantitative determination of pravastatin and its metabolite (3α-hydroxy pravastatin) in plasma and urine of pregnant patients under treatment with pravastatin, as part of a clinical trial. The method includes a one-step sample preparation by liquid-liquid extraction. The extraction recovery of the analytes ranged between 93.8 and 99.5% in plasma. The lower limits of quantitation of the analytes in plasma samples were 0.106 ng/mL for pravastatin and 0.105 ng/mL for 3α-hydroxy pravastatin, while in urine samples they were 19.7 ng/mL for pravastatin and 2.00 ng/mL for 3α-hydroxy pravastatin. The relative deviation of this method was <10% for intra- and interday assays in plasma and urine samples, and the accuracy ranged between 97.2 and 106% in plasma, and between 98.2 and 105% in urine. The method described in this report was successfully utilized for determining the pharmacokinetics of pravastatin in pregnant patients enrolled in a pilot clinical trial for prevention of preeclampsia.

Pravastatin sodium

Pravastatin sodium is an [HMG-CoA] reductase inhibitor and is a lipid-regulating drug. This monograph includes the description of the drug: nomenclature, formulae, elemental composition, solubility, appearance, and partition coefficient. The uses and the methods that have been reported for the synthesis of this drug are described. The physical methods that were used to characterize the drug are the X-ray powder diffraction pattern, thermal methods, melting point, and differential scanning calorimetry. This chapter also contains the following spectra of the drug: the ultraviolet spectrum, the vibrational spectrum, the nuclear magnetic resonance spectra, and the mass spectrum. The compendial methods of analysis include the British Pharmacopoeia and the United States Pharmacopoeia methods. Other methods of analysis that are included in this profile are spectrophotometric, electrochemical, polarographic, voltammetric and chromatographic, and immunoassay methods. The chapter also contains the pharmacokinetics, metabolism, stability, and articles that reviewed pravastatin sodium manufacturing, characterization, and analysis. One hundred and sixty-two references are listed at the end of this comprehensive profile.

High performance liquid chromatography mass spectrometric method for the simultaneous quantification of pravastatin and aspirin in human plasma: Pharmacokinetic application

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 pravastatin and aspirin in human plasma. Furosemide was used as an internal standard. Analytes and the internal standard were extracted from human plasma by liquid-liquid extraction technique using methyl tertiary butyl ether. The reconstituted samples were chromatographed on a Zorbax SB-C18 column by using a mixture of 5 mM ammonium acetate buffer and acetonitrile (20:80, 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 0.50-600.29 ng/mL for pravastatin and 20.07-2012.00 ng/mL for aspirin. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. A run time of 2.0 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.

Determination of pravastatin and pravastatin lactone in rat plasma and urine using UHPLC-MS/MS and microextraction by packed sorbent

A simple and reproducible method for the determination of pravastatin and pravastatin lactone in rat plasma and urine by means of ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) using deuterium labeled internal standards for quantification is reported. Separation of analytes was performed on BEH C(18) analytical column (50 mm × 2.1mm, 1.7 μm), using gradient elution by mobile phase consisting of acetonitrile and 1mM ammonium acetate at pH 4.0. Run time was 2 min. Quantification of analytes was performed using the SRM (selected reaction monitoring) experiment in ESI negative ion mode for pravastatin and in ESI positive ion mode for pravastatin lactone. Sample treatment consisted of a protein precipitation by ACN and microextraction by packed sorbent (MEPS) for rat plasma. Simple MEPS procedure was sufficient for rat urine. MEPS was implemented using the C8 sorbent inserted into a microvolume syringe, eVol hand-held automated analytical syringe and a small volume of sample (50 μl). The analytes were eluted by 100 μl of the mixture of acetonitrile: 0.01 M ammonium acetate pH 4.5 (90:10, v:v). The method was validated and demonstrated good linearity in range 5-500 nmol/l (r(2)>0.9990) for plasma and urine samples. Method recovery was ranged within 97-109% for plasma samples and 92-101% for the urine samples. Intra-day precision expressed as the % of RSD was lower than 8% for the plasma samples and lower than 7% for the urine samples. The method was validated with sensitivity reaching LOD 1.5 nmol/l and LOQ 5 nmol/l in plasma and urine samples. The method was applied for the measurement of pharmacokinetic plots of pravastatin and pravastatin lactone in rat plasma and urine samples.

Liquid chromatography-tandem mass spectrometric assay for pravastatin and two isomeric metabolites in mouse plasma and tissue homogenates

A bioanalytical assay for pravastatin and two isomeric metabolites, 3'α-isopravastatin and 6'-epipravastatin, was developed and validated. Mouse plasma and tissue homogenates from liver, kidney, brain and heart were pre-treated using protein precipitation with acetonitrile containing deuterated internal standards of the analytes. The extract was diluted with water and injected into the chromatographic system. This system consisted of a polar embedded octadecyl silica column using isocratic elution with formic acid in a water-acetonitrile mixture. The eluate was transferred to an electrospray interface using negative ionization and the analytes were detected and quantified with the selected reaction monitoring mode of a triple quadrupole mass spectrometer. The assay was successfully validated in a 3.4-7100ng/ml concentration range for pravastatin, 1.3-2200ng/ml for 3'α-isopravastatin and 0.5-215ng/ml for 6'-epipravastatin using only plasma for calibration. For plasma samples, subjected to full validation, within and between day precisions were 1-7% (9-18% at the LLQ level) and accuracies were between 91% and 103%. For tissue homogenates, subjected to partial validation, within and between day precisions were 2-12% (6-19% at the LLQ level) and accuracies were between 87% and 113% (81 and 113% at the LLQ level). Drug and metabolites were shown to be chemically stable under most relevant analytical conditions. Finally, the assay was successfully applied for a pilot study in mice. After intravenous administration of the drug, all isomeric compounds were found in plasma; however, in liver and kidney homogenate only the parent drug showed levels exceeding the LLQ.

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.

A rapid and specific approach for direct measurement of pravastatin concentration in plasma by LC-MS/MS employing solid-phase extraction

A rapid, specific and sensitive LC-MS/MS assay using solid-phase extraction (SPE) for the determination of pravastatin, in human plasma is described. The plasma filtrate obtained after SPE, using a polymer base, a hydrophilic-lipophilic balance (HLB) cartridge, was submitted directly to short-column liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay, with negligible matrix effect on the analysis. For validation of the method, the recovery of the free analytes was compared with that from an optimized extraction method, and the analyte stability was examined under conditions mimicking the sample storage, handling, and analysis procedures. The extraction procedure yielded extremely clean extracts with a recovery of 107.44 and 98.93% for pravastatin and IS, respectively. The intra-assay and inter-assay precisions for the samples at the LLOQ were 3.30 and 7.31% respectively. The calibration curves were linear for the dynamic range 0.5-200 ng/mL with correlation coefficient r > or = 0.9988. The intra- and inter-assay accuracy ranged from 95.87 to 112.40%. The method is simple and reliable with a total run time of 3 min. This novel validated method was applied to the pharmacokinetic (PK) study in human volunteers receiving a single oral dose of 40 mg immediate release (IR) formulation.

Analysis of five HMG-CoA reductase inhibitors-- atorvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin: pharmacological, pharmacokinetic and analytical overview and development of a new method for use in pharmaceutical formulations analysis and in vitro metabolism studies

A specific, accurate, precise and reproducible high-performance liquid chromatographic (HPLC) method was developed and validated for the simultaneous quantitation of five 3-hydroxy-3-methyglutaryl coenzyme A (HMG-CoA) reductase inhibitors, viz. atorvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin, in pharmaceutical formulations and extended the application to in vitro metabolism studies of these statins. Ternary gradient elution at a flow rate of 1 mL/min was employed on an Intertisl ODS 3V column (4.6 x 250 mm, 5 microm) at ambient temperature. The mobile phase consisted of 0.01 m ammonium acetate (pH 5.0), acetonitrile and methanol. Theophylline was used as an internal standard (IS). The HMG-CoA reductase inhibitors and their metabolites were monitored at a wavelength of 237 nm. Drugs were found to be 89.6-105.6% of their label's claim in the pharmaceutical formulations. For in vitro metabolism studies the reaction mixtures were extracted with simple liquid-liquid extraction using ethyl acetate. Baseline separation of statins and their metabolites along with IS free from endogenous interferences was achieved. Nominal retention times of IS, atorvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin were 7.5, 17.2, 21.6, 28.5, 33.5 and 35.5 min, respectively. The proposed method is simple, selective and could be applicable for routine analysis of HMG-CoA reductase inhibitors in pharmaceutical preparations as well as in vitro metabolism studies.

Electrochemical properties and square-wave voltammetric determination of pravastatin

The electrochemical reduction and adsorptive voltammetric behaviour of pravastatin have been studied by means of cyclic and square-wave voltammetry at a hanging mercury-drop electrode in electrolytes of different pH. Within the entire pH range (2.0-9.0) in Britton-Robinson buffer, pravastatin gave rise to a single voltammetric peak in the potential interval from -1.22 to -1.44 V, depending on pravastatin concentration. It was found that the reduction of pravastatin proceeds via a relatively stable intermediate, which is transformed to the final electroinactive product by a coupled chemical reaction or can be re-oxidized back to pravastatin. The rate of chemical transformation is controlled by the proton concentration. The electrode mechanism has the properties of a surface redox reaction. A sensitive analytical method for trace analysis of pravastatin based on the adsorptive stripping technique has been developed. The calibration plot was linear in the range 8x10(-8)-5x10(-7) mol L(-1). Application of the square-wave voltammetric method to determination of pravastatin in a pharmaceutical dosage form, without sample pretreatment, resulted in acceptable deviation from the stated concentration.

Quantitative determination of pravastatin and R-416, its main metabolite in human plasma, by liquid chromatography-tandem mass spectrometry

A quantitative method was developed and validated for rapid and sensitive analysis of pravastatin and R-416, the main metabolite of pravastatin, in human plasma. The analytes were extracted from plasma samples by a solid phase extraction method using a Bond Elut C(8). The method involved the use of liquid chromatography coupled with atmospheric pressure chemical ionization (APCI) and selected reaction monitoring (SRM) mass spectrometry. A pravastatin analog, R-122798, was used as the internal standard (I.S.). Separation of pravastatin, R-416 and the I.S. was accomplished using a reverse-phase column (C(18)). The components eluted were ionized by the APCI source (negative ion) and subsequently detected by a highly selective triple quadrupole mass spectrometer in the SRM mode. Linear standard curves were obtained from 0.1 ng/mL (lower limit of quantification, LLOQ) to 100 ng/mL. The intra-assay precisions (coefficient of variation) for the samples at the LLOQ were 1.8% for pravastatin and 1.6% for R-416. The intra-assay accuracy values were 95.8-107.6% for pravastatin, and 92.6-109.0% for R-416, respectively. Precision and accuracy of quality control (QC) samples were determined at concentrations of 0.5, 10 and 80 ng/mL for all analytes. The intra- and inter-assay precision calculated from QC samples were within 10% for pravastatin and within 11% for R-416. The overall recoveries for pravastatin and R-416 were 75.7-82.1% and 68.6-74.3%, respectively. Pravastatin and R-416 were stable in human plasma for 3 weeks at -20 degrees C in a freezer, up to 6h at room temperature, and up to 48 h at 6 degrees C. This assay method was successfully used to evaluate the pravastatin and R-416 levels in healthy volunteers following oral administration of Mevalotin.

Determination of pravastatin in tablets by capillary electrophoresis

Pravastatin (PRA) is an inhibitor of HMG-CoA reductase enzyme, which is clinically used as a hypolipidemic agent to reduce cholesterol level. A capillary electrophoretic method for the determination of PRA in pharmaceutical tablet formulations is described. PRA and lansoprazole as an internal standard (IS) were well migrated in the background electrolyte of 10 mM borate buffer (pH 8.5) and 10% acetonitrile using a fused silica capillary. The separation was achieved by applying 27.5 kV, detecting at 200 nm and injecting the sample for 0.5 s and with an average migration time (tm) for PRA and IS of 4.7 and 3.9 min, respectively, at ambient temperature. The results were precise and repeatable for areas of the peaks and peak normalization ratio (PNPRA/PNIS). Linearity was found in the concentration range of 1.56-7.78 x 10(-5) M. Intra-day and Inter-day assays were performed and reliable results were obtained. Limit of detection and limit of quantitation were 8 x 10(-6) and 2.4 x 10(-5) M, respectively. The proposed method was successfully applied for the analysis of PRA in the pharmaceutical tablet formulation. The method proved simple, precise and fast since the analysis can be performed in less than 5 min.

Analytical methods for the quantitative determination of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in biological samples

Published analytical methods for the quantitative determinations of presently available five 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors ("statins"), lovastatin, simvastatin, pravastatin, fluvastatin and atorvastatin, are reviewed for therapeutic drug monitoring purpose in patients. Almost all assay reviewed are based on high-performance liquid chromatography or gas chromatography. Some purification steps (liquid-liquid extraction, solid-phase extraction, etc.) have been used before they are submitted to separation by chromatographic procedures and they are detected by various detection methods like UV, fluorescence and mass spectrometry. This review shows that most method may be used quantitative determination of statins in plasma and they are suitable for therapeutic drug monitoring purpose of these drugs.