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

Critical analysis of analytical techniques developed for statins in biological fluids, environmental and fermentation samples

Statins are the most prescribed drug for regulating the high cholesterol level in the blood, which can lead to severe complications, such as cardiovascular diseases and other health complications. A wide range of analytical techniques have been employed for the quantification of statins from various origins, including fermentation derived (lovastatin, pravastatin, and compactin), semi-synthetic (simvastatin), and synthetic (atorvastatin, rosuvastatin, and fluvastatin) routes. The presence of more than one structural form and structural analogue generated in the biosynthesis pathway, as well as reaction intermediates and macromolecules in the clinical sample, complicates the quantification of statins. Furthermore, significant concentrations of statins in environmental samples pose serious health and ecology hazards, and estimating statins in those diluted samples is extremely difficult. On the other hand, the: cost, accurate estimation of the desired one from other structural forms, sample complexity, time, limits of detection and quantification, were major criteria distinguishing the usability of each technique. As a result, the current manuscript focuses on analytical techniques such as molecular spectroscopy (normal and derivatives UV-Visible spectrophotometer), chromatography (TLC, HP-TLC, HPLC, GC, swing column, micellar, and supercritical fluid), mass spectroscopy (HPLC-MS/MS and GC-MS/MS), sequential flow injection, capillary electrophoresis, and cyclic voltammetry, as well as their: optimal operating conditions, limits of detection and quantification, advancements, and limitations. Furthermore, various online and offline sample preparations (precipitation, solid phase extraction, liquid-liquid extraction, and micellar extraction) have been highlighted as an essential pretreatment technique to avoid the interference caused by structural analogues and other macromolecules. The greener and more sustainable concepts used in analytical approaches for the quantification statins are also highlighted with current advancements.

A green and sustainable UV spectrophotometric approach for simultaneous determination of rosuvastatin, pravastatin, and atorvastatin in pharmaceuticals leveraging firefly algorithm-enhanced partial least squares regression

This study aimed to develop a green and sustainable analytical method for the quantitative determination of three statins-rosuvastatin, pravastatin, and atorvastatin-using their UV spectral fingerprints. Partial Least Squares (PLS) regression combined with the Firefly Algorithm (FFA) for variable selection was employed to optimize the analysis. A partial factorial design was used to construct a 25-sample synthetic calibration set, while a central composite design served for external validation. The FFA-PLS approach demonstrated superior performance over traditional PLS models, achieving relative root mean square errors of prediction of 1.68%, 1.04%, and 1.63% for rosuvastatin, pravastatin, and atorvastatin, respectively, compared to 2.85%, 2.77%, and 3.20% for conventional PLS. FFA-PLS also enabled model simplification, reducing latent variables from 4, 3, and 4 to 2, 2, and 3 for the respective statins while requiring fewer wavelengths. Validation in accordance with ICH guidelines further confirmed the method's accuracy, precision, and selectivity. Besides, application to real pharmaceutical samples yielded mean recoveries ranging from 99.23% to 99.90%, with RSD% below 2%. Furthermore, comparative analysis with reported chromatographic methods revealed no significant differences in terms of mean and variance as calculated by a two-tailed t-test and F-test, respectively. Finally, environmental impact assessment metrics demonstrated the method's superior sustainability (AGREE score: 0.78 vs. 0.64 for HPLC; RGB12 whiteness index: 91.4% vs. 75.8% for HPLC-UV). In conclusion, the proposed UV-PLS-FFA method offers an effective, accurate, and environmentally friendly alternative for the determination of statins in pharmaceutical samples, aligning with the principles of green chemistry and sustainability and has potential for broader applicability beyond the scope of this study.

Folic acid-conjugated long circulating co-encapsulated atorvastatin and quercetin solid lipid nanoparticles: pharmacokinetics and biodistribution in rats

Background: Solid lipid nanoparticles (SLNs) have emerged as effective carriers for the simultaneous delivery of two drugs. Moreover, the surface modification of SLNs enhances their targetability and minimizes side effects, rendering them a promising and dynamic strategy for addressing various life-threatening diseases. The assessment of pharmacokinetic parameters is a critical aspect of this approach. In the present study, we report the development and validation of an LC-MS/MS-based bioanalytical method for the quantification of Atorvastatin (ATR) and Quercetin (QUER) encapsulated in folic acid-modified SLNs as a drug delivery system to estimate their pharmacokinetics and tissue distribution. Method: FA-SLNs were synthesized by amide linkage formation (carbodiimide reaction) and tested for their haemocompatibility. Further, an LC-MS/MS method was developed on a C18 (3 × 100 mm, 2.7 μm) column using 0.1% v/v formic acid in water and acetonitrile as the mobile phase with a 0.3 mL min-1 flow rate. For detection, analytes were ionized using an electron spray ionization (ESI) source in multiple reaction monitoring (MRM) mode. MRM for the ATR (559.0 → 440.2) m/z and IS (482.1 → 257.8) m/z in positive polarity, and QUER (301.9 → 151.0) m/z in negative polarity were optimized. Results: Pharmacokinetics studies demonstrated an increase in the half-lives of ATR and QUER of about 6.4-fold and 5.7-fold, respectively, from FA-SLN compared to pure drugs. Further, the active targeting facilitated by FA conjugation showed increased mean residence time (MRT) and decreased clearance time, resulting in long circulation time without the enhanced retention of drugs in the tissues of rats. These findings underscore the potential of FA-modified ATR and QUER-loaded SLNs as an advanced drug delivery strategy in improving the therapeutic outcomes.

Micellar liquid chromatography as a sustainable tool to quantify three statins in oral solid dosage forms

A method based on micellar liquid chromatography has been developed to determine rosuvastatin, lovastatin and simvastatin in oral solid dosage forms. Samples were solved in mobile phase up to the target concentration, filtered and directly injected. The three statins were resolved in 30 min, using an aqueous solution of 0.10 M sodium dodecyl sulfate - 7.0% 1-butanol, buffered at pH 3 with 0.01 M phosphate salt as mobile phase, running under isocratic mode at 1 mL/min through a C₁₈ column. Detection was at 240 nm. The effect of sodium dodecyl sulfate on elution strength was more important than that of the organic solvent. The procedure was successfully validated by the guidelines of the International Council for Harmonization in terms of: specificity, linearity (r² > 0.990), calibration range (1.5 - 15 mg/L for rosuvastatin, 0.5-10 mg/L for lovastatin and simvastatin), limit of detection (0.4, 0.2 and 0.15 mg/L for rosuvastatin, lovastatin and simvastatin, respectively), trueness (98.8-101.7%), precision (<2.7%), carry-over effect, robustness, and stability. Values were inside the acceptance criteria of the Methods, Method Verification and Validation, Food and Drug Administration-Office of Regulatory Affairs, thus ensuring the reliability of the results. The main feature was the low proportion of organic solvent used, thus making the procedure sustainable and green. Besides, it was easy-to-conduct and with high sample-throughput, and then useful for routine analysis in pharmaceutical quality control. Finally, it was applied to commercial pharmaceutical preparations.

A method of isolating and analysing drugs from cancer cells for preclinical research

The presented paper describes a new isolation method of recovery and analysis of selected drugs developed for preclinical research. The method uses the RP-HPLC technique (in a single chromatographic separation) and serves the recovery and analysis of selected drugs from neoplastic cells. It enables the determination of cytostatics statins, fibrates, and pioglitazone. Chromatographic separations of the tested compounds were carried out on a Gemini-NX 5 µ C18 (4.6 × 150 mm i.d.) column, in a gradient system with a mobile phase consisting of ACN (0.1% TFA) and water (0.1% TFA) at ambient temperature. The separations were carried out at a flow of 1 ml/min and UV detection of 220 nm. The inter-day and intra-day precision and accuracy of the method were determined. Extending the extraction time at reduced temperature resulted in a significant increase in the recovery of the pharmaceuticals in comparison with traditional extraction methods. The presence of the tested pharmaceuticals at defined retention times was confirmed by mass spectrometry. A recovery procedure for the tested compounds from biological material (medium, cell pellets) was developed at a level ranging between 93 and 99%. The utility of the new HPLC method has been confirmed in drug absorption studies as screening tests for the analysis of the new therapeutic compositions on melanoma cell lines.

Method development for quantitative determination of seven statins including four active metabolites by means of high-resolution tandem mass spectrometry applicable for adherence testing and therapeutic drug monitoring

Background Statins are used to treat and prevent cardiovascular diseases (CVDs) by reducing the total serum cholesterol concentration. Unfortunately, dose-related side effects and sub-optimal response, attributed to non-adherence amongst others, were described. Therefore, a fast and sensitive liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS) method for adherence testing and therapeutic drug monitoring of all currently marketed statins and their active metabolites in human blood plasma should be developed, validated and tested for applicability. Methods Atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin, as well as ortho- and para-hydroxy-atorvastatin, lovastatin hydroxy acid and simvastatin hydroxy acid were included and several internal standards (IS) tested. Validation was performed according to the guideline of the European Medicines Agency including selectivity, carry-over, accuracy, precision, matrix effects, dilution integrity and analyte stability. Finally, applicability was tested using 14 patient samples submitted for regular toxicological analysis. Results Due to an analytical interference of atorvastatin-d5, diazepam-d5 and pentobarbital-d5 were chosen as IS for positive and negative ionization mode, respectively. All statins and metabolites fulfilled the validation acceptance criteria except for fluvastatin, which could not be quantified reliably and reproducibly, most probably due to instability. Analyses of human plasma samples revealed concentrations of statins and metabolites below the reference plasma concentrations in the case of eight patients. However, nothing was known concerning patients' adherence and time between intake and sampling. Conclusions An LC-HRMS/MS method for identification and quantification of atorvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin and four active metabolites was successfully developed and applicability demonstrated.

Bioactive Triterpenes of Protium heptaphyllum Gum Resin Extract Display Cholesterol-Lowering Potential

Hypercholesterolemia is one of the major causes of cardiovascular disease, the risk of which is further increased if other forms of dyslipidemia occur. Current therapeutic strategies include changes in lifestyle coupled with drug administration. Statins represent the most common therapeutic approach, but they may be insufficient due to the onset of resistance mechanisms and side effects. Consequently, patients with mild hypercholesterolemia prefer the use of food supplements since these are perceived to be safer. Here, we investigate the phytochemical profile and cholesterol-lowering potential of Protium heptaphyllum gum resin extract (PHE). Chemical characterization via HPLC-APCI-HRMS² and GC-FID/MS identified 13 compounds mainly belonging to ursane, oleanane, and tirucallane groups. Studies on human hepatocytes have revealed how PHE is able to reduce cholesterol production and regulate the expression of proteins involved in its metabolism. (HMGCR, PCSK9, LDLR, FXR, IDOL, and PPAR). Moreover, measuring the inhibitory activity of PHE against HMGR, moderate inhibition was recorded. Finally, molecular docking studies identified acidic tetra- and pentacyclic triterpenoids as the main compounds responsible for this action. In conclusion, our study demonstrates how PHE may be a useful alternative to contrast hypercholesterolemia, highlighting its potential as a sustainable multitarget natural extract for the nutraceutical industry that is rapidly gaining acceptance as a source of health-promoting compounds.

Development and Validation of a Rapid Analytical Method for the Simultaneous Quantification of Metabolic Syndrome Drugs by HPLC-DAD Chromatography

Worldwide, 25% of the population suffers from metabolic syndrome (MetS). The treatment of patients with MetS regularly includes drugs prescribed simultaneously to treat several disorders that manifest at the same time, such as hypercholesterolemia, arterial hypertension, and diabetes. To the authors’ best knowledge, there is no previous published analytical method for the simultaneous quantification of drugs used in the treatment of these diseases. In the present study, a rapid high-performance liquid chromatography with a diode-array detector HPLC-DAD methodology was developed for simultaneous quantification of carvedilol (CVD), telmisartan (TEL), bezafibrate (BZT), gliclazide (GZD), and glimepiride (GMP) in bulk and pharmaceutical form. The chromatographic separation of the five pharmaceuticals was achieved on a Hypersil GOLD C18 Selectivity (5 µm, 150 × 4.60 mm2) using a mobile phase of acetonitrile (50%) and 0.02 M KH2PO4, pH 3 (50%) at a flow rate of 1 mL/min and at 25 °C. The total separation time was 9 min. The analytical method was validated following the International Conference on Harmonization guidelines. A reproducible method was obtained with acceptable limits of detection (LOD) and quantification (LOQ) for CVD (0.012 and 0.035 μg mL−1), TEL (0.103 and 0.313 μg mL−1), BZT (0.025 and 0.076 μg mL−1), GZD (0.039 and 0.117 μg mL−1), and GMP (0.064 and 0.127 μg mL−1). The validated method allowed the determination of these drugs in commercial pharmaceutical products both individually and simultaneously. The present method was found to be suitable for simultaneous quantification of the five drugs that are most commonly used in the simultaneous treatment of the metabolic syndrome.

Statins for the prevention of proliferative vitreoretinopathy: cellular responses in cultured cells and clinical statin concentrations in the vitreous

Proliferative vitreoretinopathy (PVR) with rhegmatogenous retinal detachment (RRD) is a complex inflammatory ocular disease. Statins are widely used cholesterol-lowering drugs with putative anti-inflammatory properties. In this study, we have explored their efficacy in controlling post-surgical PVR formation. Simvastatin (SIM), atorvastatin (ATV), or rosuvastatin (RSV) were added to cultures of human retinal pigment epithelial cells (ARPE-19) prior to exposure with the bacterial lipopolysaccharide (LPS), and the production of pro-inflammatory cytokines (IL-6, IL-8, MCP-1) was examined using an enzyme-linked immunosorbent assay. In addition, the concentrations of simvastatin, atorvastatin, rosuvastatin, and their metabolites were measured from the vitreal samples of 20 patients undergoing vitrectomy (16 of them receiving oral statin therapy) using an ultra-performance liquid chromatography-tandem mass spectrometer technique. All statins alleviated LPS-induced inflammation at 5 µM concentration in the ARPE-19 cell cultures. Statin levels in the vitreous samples ranged from 6 to 316 pg/mL (ca. 0.1-7 M^-10). Vitreal statin concentrations were similar to the typical steady-state unbound statin concentrations in plasma, indicating that only the unbound drug distributes from the blood circulation into the vitreous. Pharmacokinetic simulations of the intravitreal delivery of statins indicate that the measured clinical statin concentrations could be maintained with existing drug delivery technologies for months. Our results suggest that intravitreal statin therapy may have the potential in alleviating the risk of post-surgical PVR.

Simvastatin, but not pravastatin, inhibits the proliferation of esophageal adenocarcinoma and squamous cell carcinoma cells: a cell-molecular study

Background and objective

Long-term statin therapy has been shown to protect against several cancers, including esophageal cancer (EC). While the mechanisms underlying this effect are not clear. We investigated the effect of hydrophobic simvastatin and hydrophilic pravastatin on the proliferation of EC cells and sought to explore the underlying mechanisms.

Methods

Esophageal adenocarcinoma OE-19 cells and esophageal squamous cell carcinoma Eca-109 cells were treated with different concentrations of simvastatin or pravastatin for 24 h and 48 h. Cell proliferation was assessed by Cell Counting Kit-8 assay. Malondialdehyde (MDA) levels were measured by thiobarbituric acid (TBA) assay. mRNA and protein expression of COX-2 were determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot, respectively; The expression of prostaglandin E₂ (PGE₂) was measured by ELISA.

Results

Simvastatin, but not pravastatin, significantly inhibited the proliferation of OE-19 and Eca-109 cells in a dose- and time-dependent manner, accompanying with the increasing of the MDA level. Moreover, simvastatin suppressed the expression of COX-2 and PGE₂ in both OE-19 and Eca-109 cells in a dose-dependent manner.

Conclusions

Lipophilic simvastatin, but not hydrophilic pravastatin, had significant inhibitory effects on the proliferation of Eca-109 and OE-19 cells. The reduction of COX-2 and PGE₂ by simvastatin suggested that the inhibitory effect of simvastatin on the proliferation of EC cells may be independent of its lipid-lowering effect. Simvastatin may be a promising agent for the prevention and treatment of EC.

Capsaicin is beneficial to hyperlipidemia, oxidative stress, endothelial dysfunction, and atherosclerosis in Guinea pigs fed on a high-fat diet

Capsaicin has anti-inflammatory and antioxidant effects, as well as some benefits on the cardiovascular system. The exact effects of capsaicin on atherosclerosis are poorly understood. To investigate the effects of capsaicin on hyperlipidemia and atherosclerosis in guinea pigs fed on a high-fat diet, as well as its potential mechanisms. Guinea pigs (n = 48) were randomly divided into six groups (n = 8/group): normal diet (control); high fat diet (model); model + low-dose capsaicin (2.5 mg/kg); model + moderate-dose capsaicin (5 mg/kg); model + high-dose capsaicin (10 mg/kg), and model + simvastatin (1.5 mg/kg) (positive control). After 14 weeks, serum lipids, apolipoprotein B100, malondialdehyde (MDA), superoxide dismutase (SOD), nitric oxide (NO), and endothelin-1 were measured. Aortic atherosclerotic lesions were histologically examined. eNOS and iNOS were assessed by immunohistochemistry. The model group developed severe dyslipidemia and associated histologic changes and endothelial dysfunction. All doses of capsaicin decreased total cholesterol, triglycerides, low-density lipoprotein cholesterol, and apolipoprotein B-100, and increased high-density lipoprotein cholesterol (all P < 0.05). Capsaicin alleviated the plaque area (-17.9-70.5%), plaque area to intima ratio (-18.0-73.6%), and intima thickness (-20.5-83.6%) (all P < 0.05). Capsaicin decreased MDA (-45.5-76.1%), ET-1 (-19.6-51.6%), and average gray value (AGV) of eNOS (-10.9-48.8%), and increased SOD activity (+31.7-76.1%), NO (+11.2-36.8%), and AGV of iNOS (+6.8-+93.0%) (all P < 0.05). Similar changes were observed with simvastatin. Capsaicin is beneficial to hyperlipidemia and atherosclerosis in guinea pigs fed on a high-fat diet. Reduced oxidative stress and endothelial dysfunction were involved in these benefits. This could represent a novel approach to prevent cardiovascular diseases.

From Oxiranes to Oligomers: Architectures of U.S. FDA Approved Pharmaceuticals Containing Oxygen Heterocycles

Oxygen heterocycles are the second most common type of heterocycles that appear as structural components of U.S. Food and Drug Administration (FDA) approved pharmaceuticals. Analysis of our database of drugs approved through 2017 reveals 311 distinct pharmaceuticals containing at least one oxygen heterocycle. Most prevalent among these are pyranoses, with furanoses, macrolactones, morpholines, and dioxolanes rounding off the top five. The main body of this Perspective is organized according to ring size, commencing with three- and four-membered rings and ending with macrocycles, polymers, and unusual oxygen-containing heterocycles. For each section, all oxygen heterocycle-containing drugs are presented along with a brief discussion about structural and drug application patterns.

Analytical Methods for the Determination of Rosuvastatin in Pharmaceutical Formulations and Biological Fluids: A Critical Review

Rosuvastatin calcium (ROS), ( Figure 1 ) belongs to the "statins" group, which is the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor. This drug is indicated for dyslipidemias treatment and can help to decrease the level of "bad cholesterol" and can consequently reduce the development of atherosclerosis and the risk of heart diseases. ROS was developed by Astra-Zeneca and it was approved in 2003 by the FDA in the United States. In 2015, under the trade name Crestor®, it was the fourth largest selling drug in the United States with sales above $5 billion. This study presents a literature review of analytical methods for the quantification of ROS in pharmaceutical preparations and biological fluids. The major analytical methods described in this study for ROS were spectrophotometry, high-performance liquid chromatography (HPLC) coupled to ultraviolet (UV) detection, and tandem mass spectrometry (LC-MS/MS).

Development and validation of a green RP-HPLC method for the analysis of rosuvastatin: a step towards making liquid chromatography environmentally benign

The purpose of this study was to formulate and validate a new green high-performance liquid chromatography-ultraviolet (HPLC)-UV method for quick quantification of rosuvastatin calcium (ROC) in standard drugs. The results showed a combination of ethanol:methanol:ethyl acetate (6:3:1 v/v) at a rate of 1.0 ml/min to be the best for identifying ROC and its separation from its breakdown products. The identification of ROC was achieved using a NUCLEODUR 150 mm×4.6 mm RP C8 column packed using 5 μm filler as the stationary phase and detection was performed at 254 nm. The technique developed was checked for linearity, selectivity, accuracy, precision, robustness and sensitivity as well as specificity. The usefulness of the proposed process was confirmed by analyzing ROC in a prepared self-nanoemulsifying drug delivery system (SNEDDS) and over-the-counter products. The amount of ROC in SNEDDS was found to be 98.38%. The HPLC-UV system we developed effectively determined the ROC peak along with its breakdown products which confirmed the stability-indicating property of the projected system. The system could also be used to compare the solubility of rosuvastatin nanoparticles in standard drugs. These outcomes indicated that the developed HPLC could be effectively used for the regular investigation of ROC in standard drugs, various pharmaceutical formulations and drug release samples.

Spectrophotometric method for simultaneous determination of valsartan and substances from the group of statins in binary mixtures

Applicability of derivative spectrophotometry for the determination of valsartan in the presence of a substance from the group of statins was checked. The obtained results indicate that the proposed method may be effective by using appropriate derivatives: for valsartan and fluvastatin - D1, D2 and D3, for valsartan and pravastatin - D1 and D3, for valsartan and atorvastatin - D2 and D3. The method was characterized by high sensitivity and accuracy. Linearity was maintained in the following ranges: 9.28-32.48 mg mL-1 for valsartan, 8.16-28.56 mg mL-1 f or fluvastatin, 14.40-39.90 mg mL-1 for atorvastatin and 9.60-48.00 mg mL-1 for pravastatin. Determination coefficients were in the range of 0.989-0.999 depending on the analyte and the order of derivative. The precision of the method was high with RSD from 0.1 to 2.5 % and recovery of individual components was within the range of 100 ± 5 %. The developed method was successfully applied to the determination of valsartan combined with fluvastatin, atorvastatin and pravastatin in laboratory prepared mixtures and in pharmaceutical preparations.

Comparison of the elution characteristics of individual forms of lovastatin in both isocratic and gradient modes and HPLC-PDA method development for pure and fermentation-derived lovastatin

The elution characteristics of lovastatin were studied by varying the composition of mobile phase in both isocratic and gradient elution modes to comprehend the role of organic modifier and acidifier on the overall analysis time and retention time of individual forms of lovastatin. Acetonitrile has influenced on the overall analysis time, whereas the acidifier determines the retention time of hydroxy acid form of lovastatin and the retention time gap between the individual forms. A combination of acetonitrile and 0.1% trifluoroacetic acid (TFA) (60:40, v/v) in isocratic elution mode eluted both hydroxy acid and lactone forms of lovastatin at 4.5 and 5.4 min, respectively. This appears to be a better approach for the separation of pharmaceutical and clinical lovastatin samples. At isocratic elution mode, a mixture of acetonitrile and either 0.05% TFA or 0.1% H₃PO₄ of 60:40 (v/v) has eluted both hydroxy acid and lactone forms of lovastatin at 10 ± 0.5 and 17 ± 0.5 min, respectively. This is suitable for the fermentation-derived samples or for the complex mixtures of structural analogs. The fermentation broth (pH not adjusted) extracted with ethyl acetate at a ratio of 1:1 (v/v) at 60°C for 30 min was the optimal extraction condition for lovastatin.

Statins redux: A re-assessment of how statins lower plasma cholesterol

Obesity associated dyslipidemia and its negative effects on the heart and blood vessels have emerged as a major healthcare challenge around the globe. The use of statins, potent inhibitors of hydroxyl-methyl glutaryl (HMG) Co-A reductase, a rate-limiting enzyme in cholesterol biosynthesis, has significantly reduced the rates of cardiovascular and general mortality in patients with coronary artery disease. How statins lower plasma cholesterol levels presents a mechanistic conundrum since persistent exposure to these drugs in vitro or in vivo is known to induce overexpression of the HMG Co-A reductase gene and protein. In an attempt to solve this mechanistic puzzle, Schonewille et al, studied detailed metabolic parameters of cholesterol synthesis, inter-organ flux and excretion in mice treated with 3 common statins, rosuvastatin, atorvastatin or lovastatin, each with its unique pharmacokinetics. From the measurements of the rates of heavy water (D₂O) and [¹³C]-acetate incorporation into lipids, the authors calculated the rates of whole body and organ-specific cholesterol synthesis in control and statin-treated mice. These analyses revealed dramatic enhancement in the rates of hepatic cholesterol biosynthesis in statin-treated mice that concomitantly elicited lower levels of cholesterol in their plasma. The authors have provided strong evidence to indicate that statin treatment in mice led to induction of compensatory metabolic pathways that apparently mitigated an excessive accumulation of cholesterol in the body. It was noted however that changes in cholesterol metabolism induced by 3 statins were not identical. While sustained delivery of all 3 statins led to enhanced rates of biliary excretion of cholesterol and its fecal elimination, only atorvastatin treated mice elicited enhanced trans-intestinal cholesterol excretion. Thus, blockade of HMGCR by statins in mice was associated with profound metabolic adaptations that reset their cholesterol homeostasis. The findings of Schonewille et al, deserve to be corroborated and extended in patients in order to more effectively utilize these important cholesterol-lowering drugs in the clinic.

Statins increase hepatic cholesterol synthesis and stimulate fecal cholesterol elimination in mice

Statins are competitive inhibitors of HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis. Statins reduce plasma cholesterol levels, but whether this is actually caused by inhibition of de novo cholesterol synthesis has not been clearly established. Using three different statins, we investigated the effects on cholesterol metabolism in mice in detail. Surprisingly, direct measurement of whole body cholesterol synthesis revealed that cholesterol synthesis was robustly increased in statin-treated mice. Measurement of organ-specific cholesterol synthesis demonstrated that the liver is predominantly responsible for the increase in cholesterol synthesis. Excess synthesized cholesterol did not accumulate in the plasma, as plasma cholesterol decreased. However, statin treatment led to an increase in cholesterol removal via the feces. Interestingly, enhanced cholesterol excretion in response to rosuvastatin and lovastatin treatment was mainly mediated via biliary cholesterol secretion, whereas atorvastatin mainly stimulated cholesterol removal via the transintestinal cholesterol excretion pathway. Moreover, we show that plasma cholesterol precursor levels do not reflect cholesterol synthesis rates during statin treatment in mice. In conclusion, cholesterol synthesis is paradoxically increased upon statin treatment in mice. However, statins potently stimulate the excretion of cholesterol from the body, which sheds new light on possible mechanisms underlying the cholesterol-lowering effects of statins.

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.

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.

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.

Generation of polyclonal antibody with high avidity to rosuvastatin and its use in development of highly sensitive ELISA for determination of rosuvastatin in plasma

In this study, a polyclonal antibody with high avidity and specificity to the potent hypocholesterolaemic agent rosuvastatin (ROS) has been prepared and used in the development of highly sensitive enzyme-linked immunosorbent assay (ELISA) for determination of ROS in plasma. ROS was coupled to keyhole limpt hemocyanin (KLH) and bovine serum albumin (BSA) using carbodiimide reagent. ROS-KLH conjugate was used for immunization of female 8-weeks old New Zealand white rabbits. The immune response of the rabbits was monitored by direct ELISA using ROS-BSA immobilized onto microwell plates as a solid phase. The rabbit that showed the highest antibody titer and avidity to ROS was scarified and its sera were collected. The IgG fraction was isolated and purified by avidity chromatography on protein A column. The purified antibody showed high avidity to ROS; IC₅₀ = 0.4 ng/ml. The specificity of the antibody for ROS was evaluated by indirect ELISA using various competitors from the ROS-structural analogues and the therapeutic agents used with ROS in a combination therapy. The proposed ELISA involved a competitive binding reaction between ROS, in plasma sample, and the immobilized ROS-BSA for the binding sites on a limited amount of the anti-ROS antibody. The bound anti-ROS antibody was quantified with horseradish peroxidase-labeled second anti-rabbit IgG antibody (HRP-IgG) and 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate for the peroxidase enzyme. The concentration of ROS in the sample was quantified by its ability to inhibit the binding of the anti-ROS antibody to the immobilized ROS-BSA and subsequently the color intensity in the assay wells. The assay enabled the determination of ROS in plasma at concentrations as low as 40 pg/ml.

Generation of a specific polyclonal antibody with high affinity to atorvastatin and its employment in the development of ELISA for determination of atorvastatin in plasma

For the first time, a polyclonal antibody with high affinity to atorvastatin (ATR) was generated. The high specificity of the antibody for ATR among its structural analogues and co-administered therapeutic agents was proved. The antibody was employed in the development of enzyme-linked immunosorbent assay for quantitation of ATR in plasma. The assay was validated over a working range of 0.2-5 ng/mL. The intra- and interassay precisions were satisfactory; the coefficients of variations were ≤5%. The accuracy of the method was proved as the mean recovery was 96.4 ± 4.3%. The assay can be used in therapeutic monitoring and pharmacokinetic studies for ATR.

Assessment of the quality of simvastatin capsules from compounding pharmacies

OBJECTIVE

To validate a method for determining the simvastatin content of compounded capsules, using high performance liquid chromatography.

METHODS

Eighteen samples of simvastatin 40 mg capsules from compounding pharmacies in the cities of São Paulo, Guarulhos, São Bernardo do Campo and Campinas, Southeastern Brazil, prescribed for fictitious patients were assessed. The analyses were based on the Brazilian Pharmacopoeia and on the high performance liquid chromatography method, optimized and validated in accordance with national and international standards for identification and quantification tests on compounded capsules.

RESULTS

The mean weight of the capsules ranged from 70 mg to 316 mg; four samples presented weight variation outside of the specification. The simvastatin content in the capsules was within the specification in 11 samples. In six, the content ranged from 4% to 87% of the declared quantity, thereby not complying with the content requirements for the active agent. For one sample, no content or uniformity determinations were performed. In the content uniformity test, 15 samples presented indices of less than 85%, with relative standard deviations greater than 6%. Three pharmacies had met the specification in this test. In the dissolution test, eight samples presented unsatisfactory results in the first stage of the test, while the remainder presented inconclusive results.

CONCLUSIONS

The method used was shown to be suitable for application to quality control, and it revealed the poor quality of the simvastatin capsules produced by some compounding pharmacies.

A novel use of oxidative coupling reactions for determination of some statins (cholesterol-lowering drugs) in pharmaceutical formulations

New, accurate and reliable spectrophotometric methods for the assay of three statin drugs, atorvastatin calcium (AVS), fluvastatin sodium (FVS) and pravastatin sodium (PVS) in pure form and pharmaceutical formulations have been described. All methods involve the oxidative coupling reaction of AVS, FVS and PVS with 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH) in the presence of Ce(IV) in an acidic medium to form colored products with λ(max) at 566, 615 and 664 nm, respectively. Beer's law was obeyed in the ranges of 2.0-20.0, 4.9-35.4 and 7.0-30.0 μg mL(-1) for AVS-MBTH, FVS-MBTH and PVS-MBTH, respectively. Molar absorptivities for the above three methods were found to be 3.24×10(4), 1.05×10(4) and 0.68×10(4) L mol(-1) cm(-1), respectively. Statistical treatment of the experimental results indicates that the methods are precise and accurate. The proposed methods have been applied to the determination of the components in commercial forms with no interference from the excipients. A comparative study between the suggested procedures and the official methods for these compounds in the commercial forms showed no significant difference between the two methods.

Statins in dermatology

Statins are competitive inhibitors of 3-hydroxy-3-methylyglutaryl-coenzyme A reductase and reduce low-density lipoprotein-C levels. Statins are well-tolerated drugs used for prevention of atherosclerosis and cardiovascular events. Statins possess anti-inflammatory, immunomodulatory, antioxidant, metabolic, and possible anticancer effects. Statins are reported to be effective against psoriasis, dermatitis, graft-versus-host disease, uremic pruritus, vitiligo, and hirsutism. Topical forms of statins are employed in the treatment of acne, seborrhea, rosacea, and rhinophyma. Animal studies show the beneficial effect of statins against contact dermatitis and wound healing. They have promising anti-HIV effects as well. This article succinctly reviews the various cellular and molecular effects of statins, their applications in cutaneous medicine and their side effects.

Colorimetric determination of simvastatin and lovastatin in pure form and in pharmaceutical formulations

Simple, accurate and precise colorimetric method for the determination of simvastatin and lovastatin in tablets is described. The method is based on the reaction of simvastatin or lovastatin with hydroxylamine in alkaline medium to form the corresponding hydroxamic acid derivatives which, on treatment with ferric ion in acid medium, yield highly colored ferric-chelate complex with maximum absorption at 513nm. Beer's law is obeyed in the concentration ranges 0.04-0.4mgml(-1) for both simvastatin and lovastatin, respectively. Molar absorptivity values, as calculated from Beer's law data, were found to be 1.15x10(3) and 1.09x10(3)lmol(-1)cm(-1) for simvastatin and lovastatin, respectively. Optimal experimental parameters for the reaction have been studied. The validity of the described procedures was assessed. Statistical analysis of the results reflects that the proposed procedures are precise, accurate and easily applicable for the determination of simvastatin and lovastatin in pure form and in pharmaceutical preparation.

Apolipoprotein B100 secretion by cultured ARPE-19 cells is modulated by alteration of cholesterol levels

Cholesteryl ester rich apolipoprotein B100 (apoB100) lipoproteins accumulate in Bruch's membrane before the development of age-related macular degeneration. It is not known if these lipoproteins come from the circulation or local ocular tissue. Emerging, but incomplete evidence suggests that the retinal pigmented epithelium (RPE) can secrete lipoproteins. The purpose of this investigation was to determine (i) whether human RPE cells synthesize and secrete apoB100, and (ii) whether this secretion is driven by cellular cholesterol, and if so, (iii) whether statins inhibit this response. The established, human derived ARPE-19 cells challenged with 0-0.8 mM oleic acid accumulated cellular cholesterol, but not triglycerides. Oleic acid increased the amount of apoB100 protein recovered from the medium by both western blot analysis and (35) S-radiolabeled immunoprecipitation while negative stain electron microscopy showed lipoprotein-like particles. Of nine statins evaluated, lipophilic statins induced HMG-CoA reductase mRNA expression the most. The lipophilic Cerivastatin (5 μM) reduced cellular cholesterol by 39% and abrogated apoB100 secretion by 3-fold. In contrast, the hydrophilic statin Pravastatin had minimal effect on apoB100 secretion. These data suggest that ARPE-19 cells synthesize and secrete apoB100 lipoproteins, that this secretion is driven by cellular cholesterol, and that statins can inhibit apoB100 secretion by reducing cellular cholesterol.