Application of a novel ultra-low elution volume 96-well solid-phase extraction method to the LC/MS/MS determination of simvastatin and simvastatin acid in human plasma

Microextraction based on liquid-solid phase transition of benzoic acid: Extraction of statins from human urine followed by chromatographic analysis

Herein, a microextraction method was reported based on the liquid-solid phase transition of benzoic acid to quantify two statins, namely lovastatin and simvastatin in authentic human urine. The principle of the method is based on the phase transition of benzoic acid by altering the pH of the sample solution enabling efficient dispersion and phase separation in one step. Due to the moderate melting point of benzoic acid, its solidification is performed at ambient temperature without the need for sample cooling. Various experimental parameters that affect the performance of the analytes (i.e. extractant type and its concentration, acid type and concentration, and sample volume) have been examined and optimized. The method was validated based on the total error concept. For this purpose, accuracy profiles were constructed in the concentration range of 100-5000 ng mL-1 while β-expectation tolerance intervals fell within ±15% demonstrating that 95% of future results will not exceed the defined bias limits. The intra-day and inter-day method precision was less than 4.7% and 4.3% for both analytes, while the limit of detection was 15 ng mL-1 for both analytes. It was also proved that the usage of benzoic acid is advantageous in minimizing the potential inter-conversion of the analytes during the acidification step of the extraction procedure. The green potential of the proposed analytical scheme was examined based on Green Analytical Procedure index. The proposed sample pretreatment technique proved to be a valuable tool offering selectivity and rapidness. The developed method was used for the analysis of real human urine obtained after the administration of statin-based pharmaceutical formulations.

Re-examining the role of the gut microbiota in the conversion of the lipid-lowering statin monacolin K (lovastatin) into its active β-hydroxy acid metabolite

Monacolin K (MK, lovastatin), a naturally occurring statin, only exerts lipid-lowering effects in its active β-hydroxy acid form (MKA). This activation was thought to be mediated by the gut microbiota (GM). We report here for the first time that the GM does not convert MK into MKA (a spontaneous pH-dependent conversion) but catabolises MKA. The GM might hamper the lipid-lowering effects by degrading the active metabolite MKA.

Simultaneous LC-MS/MS analysis of simvastatin, atorvastatin, rosuvastatin and their active metabolites for plasma samples of obese patients underwent gastric bypass surgery

Statins, HMG-CoA reductase inhibitors, are considered the first line treatment of hyperlipidemia to reduce the risk of atherosclerotic cardiovascular diseases. The prevalence of hyperlipidemia and the risk of atherosclerotic cardiovascular diseases are higher in obese patients. Published methods for the quantification of statins and their active metabolites did not test for matrix effect of or validate the method in hyperlipidemic plasma. A sensitive, specific, accurate, and reliable LC-MS/MS method for the simultaneous quantification of simvastatin (SMV), active metabolite of simvastatin acid (SMV-A), atorvastatin (ATV), active metabolites of 2-hydroxy atorvastatin (2-OH-ATV), 4-hydroxy atorvastatin (4-OH-ATV), and rosuvastatin (RSV) was developed and validated in plasma with low (52-103 mg/dl, <300 mg/dl) and high (352-403 mg/dl, >300 mg/dl) levels of triglyceride. The column used in this method was ACQUITY UPLC BEH C18 column (2.1 × 100 mm I.D., 1.7 μm). A gradient elution of mobile phase A (10 mM ammonium formate and 0.04% formic acid in water) and mobile phase B (acetonitrile) was used with a flow rate of 0.4 ml/min and run time of 5 min. The transitions of m/z 436.3 → 285.2 for SMV, m/z 437.2 → 303.2 for SMV-A, m/z 559.2 → 440.3 for ATV, m/z 575.4 → 440.3 for 2-OH-ATV and 4-OH-ATV, m/z 482.3 → 258.1 for RSV, and m/z 412.3 → 224.2 for fluvastatin (internal standard, IS) were determined by Selected Reaction Monitoring (SRM) method to detect transitions ions in the positive ion mode. The assay has a linear range of 0.25 (LLOQ) -100 ng/ml for all six analytes. Accuracy (87-114%), precision (3-13%), matrix effect (92-110%), and extraction recovery (88-100%) of the assay were within the 15% acceptable limit of FDA Guidelines in variations for plasma with both low and high triglyceride levels. The method was used successfully for the quantification of SMV, ATV, RSV, and their active metabolites in human plasma samples collected for an ongoing clinical pharmacokinetic and pharmacodynamic study on patients prior to and post gastric bypass surgery (GBS).

In vitro and in vivo investigation of the gastrointestinal behavior of simvastatin

Simvastatin (SV) is marketed as a lactone ester prodrug which is hydrolyzed to the active simvastatin hydroxyacid (SVA). SV is characterized by a low solubility and undergoes extensive first-pass metabolism. In this study, the influence of the upper gastrointestinal environment on the intraluminal behavior of simvastatin was investigated by a series of in vitro experiments. Dissolution, stability and two-stage dissolution tests were performed using simulated and human gastrointestinal fluids. The dissolution studies revealed a relatively slow dissolution of SV as well as conversion of SV to SVA. The hydrolysis of SV was further examined and stability studies indicated a faster conversion in gastric fluids than in intestinal fluids. These isolated phenomena were then confirmed by the more integrative two-stage dissolution studies. To estimate the predictive value of the in vitro tests, an additional in vivo study was performed in which the gastrointestinal concentration-time profiles also revealed a slow dissolution of SV and faster degradation of SV to SVA in the stomach than in the intestinal tract. However, the plasma concentrations of SV and SVA did not directly correlate with the observed gastrointestinal concentrations, suggesting that gut wall and hepatic metabolism have a greater impact on systemic exposure of SV than the intraluminal interconversion between SV and SVA.

Development and Validation of an LC-MS-MS Method for the Simultaneous Determination of Simvastatin, Simvastatin Acid and Ezetimibe in Human Plasma and Its Application to Pharmacokinetic Study in the Indian Population

A simple, selective, sensitive and high-throughput liquid chromatography-tandem mass spectrometry (LC-MS-MS) method has been developed and validated for the simultaneous quantification of simvastatin (SS), simvastatin acid (SSA, active metabolite of SS) and ezetimibe (EZM) in K2 EDTA containing human plasma, using simvastatin D6, simvastatin acid D3 and ezetimibe D4 as internal standards (ISTDs), respectively. A volume of plasma sample of only 400 µL was processed by the solid phase extraction technique; then 20 µL of processed sample was run on a Phenomenex, Kinetix XB C18, 150 × 4.6 mm, 5 µm column using an isocratic mobile phase consisting of 10 mM ammonium formate buffer (pH 4.0 ± 0.3): acetonitrile (27 : 73, v/v) with a run time of 6.3 min. The precursor and product ions of SSA, EZM and their ISTDs were monitored on a triple quadrupole instrument operated in the negative ionization mode, and SS was monitored in the positive mode. The method was validated over a concentration range of 0.2-80 ng/mL for SS, 0.1-60 ng/mL for SSA and 0.05-15 ng/mL for EZM. The method has been successfully applied in clinical pharmacokinetic study in the Indian population. The Cmax, AUC0-inf and Tmax values obtained in our study were 10.61 ± 5.287, 77.58 ± 29.367 and 1.62 ± 0.436 for EZM; 69.74 ± 45.274, 190.71 ± 107.271 and 1.74 ± 0.480 for SS; and 25.36 ± 23.576, 139.24 ± 131.653 and 3.95 ± 0.671 for SSA, respectively.

Validated UPLC-MS/MS method for simultaneous determination of simvastatin, simvastatin hydroxy acid and berberine in rat plasma: Application to the drug-drug pharmacokinetic interaction study of simvastatin combined with berberine after oral administration in rats

A rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method was developed and validated for simultaneous quantification of simvastatin (SV), its metabolite simvastatin hydroxy acid (SVA) and berberine (BBR) in rat plasma. Separation was performed on Poroshell 120 EC-C18 column (4.6×50mm, 2.7μm) using gradient elution by mobile phase containing acetonitrile and 10mM ammonium acetate (pH 4.5). Polarity switch (positive-negative-positive ionization mode) was performed in a total run time of 4.0min. The lower limits of quantification (LLOQ) for SV, SVA and BBR were 0.10, 0.20 and 0.10ng/mL, respectively. The response function was established for concentration range of 0.10-100ng/mL for SV and BBR and 0.20-3000ng/mL for SVA, with a coefficient of correlation of >0.99 for all the compounds. The proposed method was applied to the drug-drug pharmacokinetic interaction study of SV combined with BBR after oral administration in rats.

A Simple Protein Precipitation-based Simultaneous Quantification of Lovastatin and Its Active Metabolite Lovastatin Acid in Human Plasma by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry using Polarity Switching

Lovastatin is an anti-cholesterol lactone drug indicated for the treatment of hyperlipidemia and to reduce the risk of coronary heart disease. It is converted to the β-hydroxy acid form (lovastatin acid) in vivo, which is the major pharmacologically active metabolite. Here, we describe the development and validation of an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)-based method utilizing polarity switching for the simultaneous quantification of lovastatin and lovastatin acid in human plasma. Simple protein precipitation extraction and direct injection of the extracted samples without drying/reconstitution showed good recoveries of both analytes (~70%). The developed method exhibited satisfactory intra-day and inter-day accuracy and precision. The interconversion between lovastatin and lovastatin acid during sample preparation and storage was minimal (< 1.9%). The lower limits of quantification were 0.5 and 0.2 nM (or 0.2 and 0.084 ng/mL) for lovastatin and lovastatin acid, respectively, using only 50 μL of plasma during extraction. The validated method was successfully applied to analyze plasma samples obtained from a healthy human subject who enrolled in a clinical drug interaction study involving lovastatin.

Comparison of conventional and supported liquid extraction methods for the determination of sitagliptin and simvastatin in rat plasma by LC-ESI-MS/MS

Three extraction methods were compared for their efficiency to analyze sitagliptin and simvastatin in rat plasma by LC–MS/MS, including (1) liquid–liquid extraction (LLE), (2) solid phase extraction (SPE) and (3) supported liquid extraction (SLE). Comparison of recoveries of analytes with different extraction methods revealed that SLE was the best extraction method. The detection was facilitated with ion trap-mass spectrometer by multiple reactions monitoring (MRM) in a positive ion mode with ESI. The transitions monitored were m/z 441.1→325.2 for simvastatin, 408.2→235.1 for sitagliptin and 278.1→260.1 for the IS. The lower limit of quantification (LLOQ) was 0.2 ng/mL for sitagliptin and 0.1 ng/mL for simvastatin. The effective SLE offers enhanced chromatographic selectivity, thus facilitating the potential utility of the method for routine analysis of biological samples along with pharmacokinetic studies.

Method Validation for Analysis of Simvastatin in Human Plasma Using Liquid Chromatography Tandem Mass Spectrometry (LC-MS-MS)

INTRODUCTION

The Liquid Chromatography Tandem Mass Spectrometry (LC-MS-MS) for determination simvastatin in human plasma has been developed after extraction by by ethyl acetate and hexane (90/10%, v/v) using lovastatin as internal standard.

MATERIAL AND METHODS

The mobile phase consisting of mixture of acetonitrile and water (75/25%, v/v) 500μL/min by separated the solutes on a C18 column.

DISCUSSION

The lower limit of quantitation of 0.25 ng/mL was achieved when the calibration curve was linear from 0.25-50 ng/mL. The entire run time for analysis was only 6 min. The quantitation in the selective reaction monitoring (SRM) in positive ion mode, the daughter ions m/z 325 for simvastatin and m/z 285 for lovastatin were used. The Parent ions in positive ion mode were m/z 441.3 for simvastatin and m/z 405.1 for lovastatin. The intra-day coefficients of variation were less than 14% while the inter-day coefficients of variation were less than 10%.

CONCLUSION

The LC-MS-MS detection is sensitive due to its capability to eliminate interferences from endogenous components.

Experimental nonalcoholic steatohepatitis increases exposure to simvastatin hydroxy acid by decreasing hepatic organic anion transporting polypeptide expression

Simvastatin (SIM)-induced myopathy is a dose-dependent adverse drug reaction (ADR) that has been reported to occur in 18.2% of patients receiving a 40- to 80-mg dose. The pharmacokinetics of SIM hydroxy acid (SIMA), the bioactive form of SIM, and the occurrence of SIM-induced myopathy are linked to the function of the organic anion transporting polypeptide (Oatp) hepatic uptake transporters. Genetic polymorphisms in SLCO1B1, the gene for human hepatic OATP1B1, cause decreased elimination of SIMA and increased risk of developing myopathy. Nonalcoholic steatohepatitis (NASH) is the most severe form of nonalcoholic fatty liver disease, and is known to alter drug transporter expression and drug disposition. The purpose of this study was to assess the metabolism and disposition of SIM in a diet-induced rodent model of NASH. Rats were fed a methionine- and choline-deficient diet for 8 weeks to induce NASH and SIM was administered intravenously. Diet-induced NASH caused increased plasma retention and decreased biliary excretion of SIMA due to decreased protein expression of multiple hepatic Oatps. SIM exhibited increased volume of distribution in NASH as evidenced by increased muscle, decreased plasma, and no change in biliary concentrations. Although Cyp3a and Cyp2c11 proteins were decreased in NASH, no alterations in SIM metabolism were observed. These data, in conjunction with our previous data showing that human NASH causes a coordinated downregulation of hepatic uptake transporters, suggest that NASH-mediated transporter regulation may play a role in altered SIMA disposition and the occurrence of myopathy.

Simultaneous quantification of simvastatin and simvastatin hydroxy acid in blood serum at physiological pH by ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC/MS/MS)

Simvastatin attenuates airway inflammation and hyperreactivity, hallmarks of asthma, in allergen-challenged mice. As such, it is under consideration as a novel therapeutic, thus it is important to quantify the levels of simvastatin and its pharmacologically active and interconvertible metabolite, simvastatin hydroxy acid, that can be attained in the body. Methods exist to measure the concentrations of these compounds in biological media; however they do not maintain a physiological pH, and as a result do not accurately measure the ratio of these two compounds that exists in vivo. We developed a new method to measure simvastatin and simvastatin hydroxy acid more accurately in serum from mice by ultra high performance liquid chromatography-tandem mass spectrometry. We minimized the time that the compounds were in aqueous solution, and buffered samples to a physiological pH value of 7.4. Limits of quantification (LOQ) were 0.16 ng mL(-1) extract (1.3 ng mL(-1) serum) for simvastatin, and 8.3 ng mL(-1) extract (66 ng mL(-1) serum) for simvastatin hydroxy acid, respectively. No interconversion was observed, based on spike-and-recovery experiments of solutions containing both compounds. The method was applied using biological samples from mice challenged with house dust mite extract and simultaneously treated with subcutaneous simvastatin injection. Simvastatin hydroxy acid concentrations became significantly increased after a 2 week pre-treatment regime, whereas simvastatin concentrations were below the LOQ for all serum samples.

Utility of Oatp1a/1b-knockout and OATP1B1/3-humanized mice in the study of OATP-mediated pharmacokinetics and tissue distribution: case studies with pravastatin, atorvastatin, simvastatin, and carboxydichlorofluorescein

Although organic anion transporting polypeptide (OATP)-mediated hepatic uptake is generally conserved between rodents and humans at a gross pharmacokinetic level, the presence of three major hepatic OATPs with broad overlap in substrate and inhibitor affinity, and absence of rodent-human orthologs preclude clinical translation of single-gene knockout/knockin findings. At present, changes in pharmacokinetics and tissue distribution of pravastatin, atorvastatin, simvastatin, and carboxydichlorofluorescein were studied in oatp1a/1b-knockout mice lacking the three major hepatic oatp isoforms, and in knockout mice with liver-specific knockin of human OATP1B1 or OATP1B3. Relative to wild-type controls, oatp1a/1b-knockout mice exhibited 1.6- to 19-fold increased intravenous and 2.1- to 115-fold increased oral drug exposure, due to 33%-75% decreased clearance, 14%-60% decreased volume of distribution, and ≤74-fold increased oral bioavailability, with the magnitude of change depending on the contribution of oatp1a/1b to pharmacokinetics. Hepatic drug distribution was 4.2- to 196-fold lower in oatp1a/1b-knockout mice; distributional attenuation was less notable in kidney, brain, cardiac, and skeletal muscle. Knockin of OATP1B1 or OATP1B3 partially restored control clearance, volume, and bioavailability values (24%-142% increase, ≤47% increase, and ≤77% decrease vs. knockout, respectively), such that knockin pharmacokinetic profiles were positioned between knockout and wild-type mice. Consistent with liver-specific humanization, only hepatic drug distribution was partially restored (1.3- to 6.5-fold increase vs. knockout). Exposure and liver distribution changes in OATP1B1-humanized versus knockout mice predicted the clinical impact of OATP1B1 on oral exposure and contribution to human hepatic uptake of statins within 1.7-fold, but only after correcting for human/humanized mouse liver relative protein expression factor (OATP1B1 = 2.2, OATP1B3 = 0.30).

Rapid quantitative analysis of clarithromycin in rat plasma by UPLC-MS/MS after intravenous injection of the clarithromycin-loaded ultrafine PLGA nanoparticles

Nanoparticles were designed to encapsulate drugs to alter their pharmacological behaviors, therefore, it is very essential to monitor the pharmacokinetic profile of drug encapsulated in nanoparticles in order to clarify and predict their efficacy and side effects. In this paper, we reported a simple, rapid μ-elution 96-well solid phase extraction (μSPE) method combining with ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for determination of nanoformulated drug in rat plasma. This method presented satisfactory results in terms of sensitivity, precision, accuracy, and recovery, for the first time, of quantitatively analyzing clarithromycin (CLA) in rat plasma after intravenous administration CLA-loaded ultrafine PLGA nanoparticles for pharmacokinetic study. This method has been proved to be fast, reliable and reproducible to accurately analyze drug encapsulated in polymeric nanoparticles sample for a pharmacokinetic study.

Synthesis, characterization and quantification of simvastatin metabolites and impurities

Simvastatin is used in treatment of hypercholesterolemia because it regulates cholesterol synthesis as a result of its β-hydroxy acid acting as an inhibitor of 3-hydroxy-methylglutaryl coenzyme A (HMG-CoA). The present communication deals with synthesis, characterization and development of accurate, precise and sensitive Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method for simultaneous estimation of simvastatin and its synthetic impurities. The impurities methyl ether and β-hydroxy acid of simvastatin were synthesized in the laboratory and characterized by MS, NMR and FT-IR spectroscopy. The separation of simvastatin and its impurities was carried out on an isocratic JASCO RP-HPLC system using KYA TECH HIQ SIL C₁₈ column (150 × 4.6 mm internal diameter, particle size 5 μm) operating at ambient temperature using acetonitrile:water (80:20 v/v) with 0.1% orthophosphoric acid as mobile phase. The method developed for HPLC analysis of three impurities along with simvastatin was validated using ICH Q2B (R1) guidelines and it complied with these guidelines. The results of analysis were found to be in the range of 98.14% to 101.89% for all analytes with acceptable accuracy and precision. The method can be used for detection and quantification of synthetic impurities in bulk or formulations of simvastatin.

Clinical relevance of liquid chromatography tandem mass spectrometry as an analytical method in microdose clinical studies

PURPOSE

To investigate the potency of LC-MS/MS by means of sensitivity and the applicability for cassette dosing in microdose clinical trials.

METHODS

Thirty one top-selling 31 drugs were spiked to human plasma, extracted, and analyzed by LC-MS/MS.

RESULTS

The lower limits of quantification for each drug varied from 0.08 to 50 pg/mL, and were lower than one eighth of the assumed maximum plasma concentration at microdose in all drugs except for losartan, indicating the high performance in acquisition of full pharmacokinetic profiles at microdose. We also succeeded in simultaneous analysis of multiple compounds, assuming a situation of cassette dosing in which multiple drug candidates would be administrated simultaneously.

CONCLUSIONS

Together with the features of LC-MS/MS, such as immediate verification, the utilization of non-radiolabeled drugs and no special facilities, we suppose that LC-MS/MS analysis would be widely applicable in conducting microdose clinical studies.

High-throughput salting-out assisted liquid/liquid extraction with acetonitrile for the simultaneous determination of simvastatin and simvastatin acid in human plasma with liquid chromatography

Simvastatin (SS) is an effective cholesterol-lowering medicine, and is hydrolyzed to simvastatin acid (SSA) after oral administration. Due to SS and SSA inter-conversion and its pH and temperature dependence, SS and SSA quantitation is analytically challenging. Here we report a high-throughput salting-out assisted liquid/liquid extraction (SALLE) method with acetonitrile and mass spectrometry compatible salts for simultaneous LC-MS/MS analysis of SS and SSA. The sample preparation of a 96-well plate using SALLE was completed within 20 min, and the SALLE extract was diluted and injected into an LC-MS/MS system with a cycle time of 2.0 min/sample. The seamless interface of SALLE and LC-MS eliminated drying down step and thus potential sample exposure to room or higher temperature. The stability of SS and SSA in various concentration ratios in plasma was evaluated at room and low (4 degrees C) temperature and the low temperature (4 degrees C) was found necessary to maintain sample integrity. The short sample preparation time along with controlled temperature (2-4 degrees C) and acidity (pH 4.5) throughout sample preparation minimized the conversion of SS-->SSA to < or = 0.10% and the conversion of SSA-->SS to 0.00% The method was validated with a lower limit of quantitation (LLOQ) of 0.094 ng mL(-1) for both SS and SSA and a sample volume of 100 microL. The method was used for a bioequivalence study with 4048 samples. Incurred sample reproducibility (ISR) analysis of 362 samples from the study exceeded ISR requirement with 99% re-analysis results within 100+/-20% of the original analysis results.

Ultra high performance liquid chromatography tandem mass spectrometric detection in clinical analysis of simvastatin and atorvastatin

Simvastatin and atorvastatin belong to the group of hypolipidemic drugs, more exactly to the second generation of inhibitors of microsomal 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. They induce a significant reduction in total cholesterol, low-density lipoprotein cholesterol and plasma triglycerides, therefore they are widely used in the treatment of hypercholesterolemia even of its severe form-familiar hypercholesterolemia. Simvastatin and atorvastatin as the most widely used statins in clinical treatment and their hydroxy-acid/lactone forms were determined by means of UPLC in connection with triple quadrupole mass spectrometer. Deuterium labeled reference standard compounds were used as internal standards for the quantitation. Separation was performed on Acquity BEH C18 (100 mm x 2.1 mm, 1.7 microm) using gradient elution by mobile phase containing acetonitrile and ammonium acetate pH 4.0, which is convenient in order to prevent interconversion of analytes. ESI in positive mode was used for the ionization of all compounds. Two SRM (selected reaction monitoring) transitions were carefully optimized for each analyte in order to get high sensitivity and selectivity. SPE on Discovery DSC-18 was used as a sample preparation step. Intra-day precision was generally within 10% RSD, while inter-day precision within 15% RSD. Method accuracy expressed as recovery ranged from 75 to 100%. The method was validated with the sensitivity reaching LOQ 0.08-5.46 nmol/l and LOD 0.01-1.80 nmol/l in biological samples. Atorvastatin, simvastatin, its metabolites and hydroxy-acid/lactone forms were monitored in human serum and in lipoprotein fractions (LDL, HDL and VLDL) at patients with end stage renal diseases.

Quantitative determination of BMS-378806 in human plasma and urine by high-performance liquid chromatography/tandem mass spectrometry

BMS-378806 is a human immunodeficiency virus (HIV) entry inhibitor that is being developed for the oral treatment of HIV infection. Human plasma and urine LC/MS/ MS methods have been developed and validated for the quantitation of BMS-378806. For human plasma method, methyl t-butyl ether was used to extract BMS-378806 from plasma in a 96-well format, and the organic layers were dried down and then reconstituted for the injection, while a dilute-and-shoot approach was used for human urine method in a 96-well format. Chromatographic separation was achieved isocratically on a Phenomenex C18 (2) Luna column (2 x 50 mm2, 5 microm). The mobile phase contained 60:40 v/v of 0.1% formic acid in water and ACN. Detection was by positive ion electrospray MS/MS. The standard curves ranged from 1.25 to 1000 ng/mL for the plasma assay and from 10 to 5000 ng/mL for the urine assay. The curves were fitted to a 1/x2 weighted quadratic regression model for both methods. The validation results demonstrated that both methods had satisfactory precision and accuracy across the calibration ranges. The methods were applied to the analysis of human plasma and urine samples from a single ascending dose clinical study to assess the pharmacokinetics of the drug. The pharmacokinetic analysis results indicated the absorption and disposition of the drug was rapid. The systemic exposure of BMS-378806 was generally dose proportional among the doses from 100 to 1200 mg, but not dose proportional to 1600 mg. There were modest increases in the systemic exposure when the drug was given with food or given as a solution formulation. Renal excretion was not a substantial elimination pathway of the drug. BMS378806 was safe and well tolerated over a dose range of 100-1600 mg administered as a single oral dose.

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.