HPLC methods for the determination of simvastatin and atorvastatin

Occurrence and fate of rosuvastatin, rosuvastatin lactone, and atorvastatin in Canadian sewage and surface water samples

Rosuvastatin (RST) and atorvastatin (ATO) are prescription drugs and members in the statin family used for the treatment of elevated cholesterol levels. A method using solid-phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of ATO, RST and its metabolite rosuvastatin lactone (RSTL) in sewage and surface water samples has been developed. In the influent and effluent samples collected from 11 sewage treatment plants located in Ontario, Canada, ATO, RST, and RSTL were detected in all samples with median concentrations of 166 ng L(-1) (influent) and 77 ng L(-1) (effluent) for ATO, 448 ng L(-1) (influent) and 324 ng L(-1) (effluent) for RST, as well as 158 ng L(-1) (influent) and 41 ng L(-1) (effluent) for RSTL. Due to the inter-conversion between RST and RSTL, the total concentration of RST and RSTL in a sewage sample should be reported. The median removal rate by wastewater treatment was 66% for ATO and 22% for RST and RSTL combined. These statins were quite persistent in sewage. After a storage period of 21 and 62 days, there was only a slight decrease in ATO concentration and no change in the total RST concentrations. These three compounds were also detected in a number of surface water samples at low ng L(-1) concentrations. This is the first reported occurrence and fate of RST and RSTL in the Canadian aquatic environment.

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.

Selectivity differences between alkyl and polar-modified alkyl phases in reversed phase high performance liquid chromatography

Compared to conventional C18 phases, polar-modified phases have distinct differences with regards to chromatographic behavior. In the present study, ODS phases and polar-modified phases were synthesized. The columns containing these new packings demonstrated satisfactory stability under both acidic (pH 1.5) and basic (pH 10) conditions. We evaluated the selectivity differences between alkyl and polar-modified alkyl RP columns by using a range of neutral analytes. The polar-modified alkyl phases showed excellent peak shapes for almost all compounds. We also compared the selectivity differences between them for separating nucleotides by using 100% aqueous mobile phase and tricyclic antidepressants in the intermediate pH mobile phases. The results demonstrated that polar-modified phases display a significantly reduced hydrophobic nature and a significantly reduced silanol activity compared to the conventional C18 phases.

Quantification of atorvastatin calcium in tablets by FT-Raman spectroscopy

The FT-Raman quantification of atorvastatin calcium in tablets was performed using the partial least squares (PLS), principal component regression (PCR) and counter-propagation artificial neural networks (CP-ANN) methods. To compare the predictive abilities of the elaborated models, the relative standard errors of prediction (RSEP) were calculated. The application of PLS, PCR and 6x6 CP-ANN provided models of comparable quality. RSEP error values in the range of 1.9-2.8% for calibration and validation data sets were obtained for the three procedures applied. Four commercial products containing 10, 20 or 40 mg of atorvastatin calcium per tablet were successfully quantified. Concentrations found from the Raman data analysis correlate strongly with the declared values, with a recovery of 98.5-101.3%, and with the results of reference analysis, with the recovery of 98.9-102.1%, for the different models. The proposed procedure can be a fast, precise and convenient method of atorvastatin calcium quantification in commercial tablets.