Clinical pharmacokinetics of pravastatin

Effect of statins on mitochondrial function and contractile force in human skeletal and cardiac muscle

OBJECTIVES AND BACKGROUND

The success of statin therapy in reducing cardiovascular morbidity and mortality is contrasted by the skeletal muscle complaints, which often leads to nonadherence. Previous studies have shown that inhibition of mitochondrial function plays a key role in statin intolerance. Recently, it was found that statins may also influence energy metabolism in cardiomyocytes. This study assessed the effects of statin use on cardiac muscle ex vivo from patients using atorvastatin, rosuvastatin, simvastatin or pravastatin and controls.

METHODS

Cardiac tissue and skeletal muscle tissue were harvested during open heart surgery after patients provided written informed consent. Patients included were undergoing cardiac surgery and either taking statins (atorvastatin, rosuvastatin, simvastatin or pravastatin) or without statin therapy (controls). Contractile behaviour of cardiac auricles was tested in an ex vivo set-up and cellular respiration of both cardiac and skeletal muscle tissue samples was measured using an Oxygraph-2k. Finally, statin acid and lactone concentrations were quantified in cardiac and skeletal homogenates by LC-MS/MS.

RESULTS

Fatty acid oxidation and mitochondrial complex I and II activity were reduced in cardiac muscle, while contractile function remained unaffected. Inhibition of mitochondrial complex III by statins, as previously described, was confirmed in skeletal muscle when compared to control samples, but not observed in cardiac tissue. Statin concentrations determined in skeletal muscle tissue and cardiac muscle tissue were comparable.

CONCLUSIONS

Statins reduce skeletal and cardiac muscle cell respiration without significantly affecting cardiac contractility.

Topical delivery of extracted curcumin as curcumin loaded spanlastics anti-aging gel: Optimization using experimental design and ex-vivo evaluation

Objective

This study aimed to extract and separate the organic coloring agent known as Curcumin from the rhizomes of Curcuma longa, and then to create Spanlastics that were loaded with curcumin using the ethanol injection technique. The optimized Spanlastic dispersions were then incorporated into a gel preparation for topical anti-aging use. The Spanlastic dispersions were analyzed for particle size, zeta potential, drug loading efficiency, and in vitro release profile. Furthermore, the rheological properties of the gel preparation were assessed, and a skin penetration study was conducted using confocal microscopy.

Methods

Twelve different Curcumin-loaded Spanlastic dispersions using the ethanol injection method with Span® 60 as a surfactant and Tween® 80 as an edge activator in varying ratios. The dispersions were then subjected to various tests, such as particle size analysis, zeta potential measurement, drug entrapment efficiency assessment, and in vitro release profiling. The optimized formula was selected using Design-Expert® software version 13, then used to create a gel preparation, which utilized 2% HPMC E50 as a gelling polymer. The gel was evaluated for its rheological properties and analyzed using confocal microscopy. Additionally, Raman analysis was performed to ensure that the polymers used in the gel were compatible with the drug substance.

Results

F5 formula, (that contains 10 mg Curcumin, and mixture 5 of span-tween mixtures that consist of 120 mg Span® 60 with 80 mg Tween® 80) was selected as the optimized formula with a desirability produced by Design Expert® software equal to 0.761, based on its particle size (212.8 ± 4.76), zeta potential (-29.4 ± 2.11), drug loading efficiency (99.788 ± 1.34), and in vitro release profile evaluations at Q 6hr equal to almost 100 %. Statistical significance (P < 0.05) was obtained using one-way ANOVA. Then F5 was used to formulate HPMC E50 gel-based preparations. The gel formula that was created and analyzed using Raman spectroscopy demonstrated no signs of incompatibility between the Curcumin and the polymers that were utilized.The confocal spectroscopy found that the anti-aging gel preparation showed promising results in terms of skin penetration. Also, images revealed that the gel could penetrate the layers of the skin (reached a depth of about 112.5 μm), where it could potentially target and reduce the appearance of fine lines and wrinkles. The gel also appeared to be well-tolerated by the skin, with no signs of irritation or inflammation observed in the images.

Conclusion

The obtained results successfully confirmed the potential of the promising (F5) formula to produce sustained release action and its ability to be incorporated into 2% HPMC E50 anti-aging gel. The confocal microscopy study suggested that the anti-aging gel had the potential to be an effective and safe topical treatment for aging skin.

An overview on nanoplatforms for statins delivery: Perspectives for safe and effective therapy

Statins are the most widely used pharmacological agents for reducing blood cholesterol levels and treating atherosclerotic cardiovascular diseases. Most of the statins' derivatives have been limited by water solubility, bioavailability, and oral absorption, which has led to adverse effects on several organs, especially at high doses. As an approach to reducing statin intolerance, achieving a stable formulation with improved efficacy and bioavailability at low doses has been suggested. Nanotechnology-based formulations may provide a therapeutic benefit over traditional formulations in terms of potency and biosafety. Nanocarriers can provide tailored delivery platforms for statins, thereby enhancing the localized biological effects and lowering the risk of undesired side effects while boosting statin's therapeutic index. Furthermore, tailored nanoparticles can deliver the active cargo to the desired site, which culminates in reducing off-targeting and toxicity. Nanomedicine could also provide opportunities for therapeutic methods by personalized medicine. This review delves into the existing data on the potential improvement of statin therapy using nano-formulations.

Detection of 4a,5-dihydropravastatin as Impurity in the Cholesterol Lowering Drug Pravastatin

Dihydro analogues are known byproducts of the fermentative production of statins and cannot be detected with existing pharmacopoeia analysis methods. We detected dihydropravastatin in most commercial formulations of pravastatin with LC-MS, in some cases in levels requiring identification. In fermentation broth samples of the single step production of pravastatin, we detected and identified for the first time 4a,5-dihydropravastatin, and confirmed that after several recrystallization steps this impurity can be fully removed from the pravastatin powder.

Anti-TNF effect of combined pravastatin and cilostazol treatment in an in vivo mouse model

Objectives: Pravastatin and cilostazol are used as lipid-lowering and antiplatelet agents, respectively. Regarding their well-known anti-inflammatory effects, the additive effect of the two drugs on anti-TNF functions has not yet been investigated. In the present investigation, the beneficial effect of combined pravastatin and cilostazol on their anti-TNF activities was assessed using an in vivo mouse model. Methods: Mice were pretreated with pravastatin and/or cilostazol (40 mg/kg of each), orally once two hour prior to an LPS (5 mg/kg, i.p.) challenge. One hour post challenge, blood and descending aorta were collected for serum TNF levels and immune cell infiltration analyses. For survival analysis, pravastatin and/or cilostazol (40 mg/kg of each) were administered 30 minutes prior to d-galactosamine administration (700 mg/kg, i.p.) and TNF (10 µg/kg, i.p.) challenge and mice survival was monitored. We also examined the effect of either drug or the combination of drugs on TNF-mediated MAPK and NF-κB signaling, using Western blot analysis. Results: Combined treatment of pravastatin and cilostazol significantly decreased serum TNF release and immune cell infiltration in the descending aorta following LPS administration, compared to each single treatment. Additionally, the combined drugs significantly decreased TNF-mediated mouse mortality and downregulated TNF-induced MAPK and NF-κB activation. Conclusions: These findings suggest that combined pravastatin and cilostazol is more effective for reducing TNF-driven inflammation through their anti-TNF activity than monotherapy.

Statins and the Brain: More than Lipid Lowering Agents?

BACKGROUND

Statins represent a class of medications widely prescribed to efficiently treat dyslipidemia. These drugs inhibit 3-βhydroxy 3β-methylglutaryl Coenzyme A reductase (HMGR), the rate-limiting enzyme of mevalonate (MVA) pathway. Besides cholesterol, MVA pathway leads to the production of several other compounds, which are essential in the regulation of a plethora of biological activities, including in the central nervous system. For these reasons, statins are able to induce pleiotropic actions, and acquire increased interest as potential and novel modulators in brain processes, especially during pathological conditions.

OBJECTIVE

The purpose of this review is to summarize and examine the current knowledge about pharmacokinetic and pharmacodynamic properties of statins in the brain. In addition, effects of statin on brain diseases are discussed providing the most up-to-date information.

METHODS

Relevant scientific information was identified from PubMed database using the following keywords: statins and brain, central nervous system, neurological diseases, neurodegeneration, brain tumors, mood, stroke.

RESULTS

315 scientific articles were selected and analyzed for the writing of this review article. Several papers highlighted that statin treatment is effective in preventing or ameliorating the symptomatology of a number of brain pathologies. However, other studies failed to demonstrate a neuroprotective effect.

CONCLUSION

Even though considerable research studies suggest pivotal functional outcomes induced by statin therapy, additional investigation is required to better determine the pharmacological effectiveness of statins in the brain, and support their clinical use in the management of different neuropathologies.

Spray-dried pH-sensitive microparticles: effectual methodology to ameliorate the bioavailability of acid labile pravastatin

Pravastatin is a promising drug utilized in the treatment of hyperlipidemia, yet, its main clinical limitation is due to gastric liability which fractions its oral bioavailability to less than 18%. The purpose of the current study is to encapsulate pravastatin into Eudragit^®-based spray-dried microparticles aspiring to overcome its acid liability. With the aim to optimize the microparticles, formulation and process parameters were studied through acid resistance challenging test. Physicochemical characterization of the optimized spray-dried pH-sensitive microparticles namely; in-vitro dissolution, surface morphology, compatibility, and solid-state studies were performed. Moreover, in-vivo evaluation of the microparticles and accelerated stability studies were carried out. The results outlined that polymer to drug ratio at 5:1 and pravastatin concentration at 1%w/w in spray-drying feed solution showed 38.55% and 53.97% encapsulation efficiency, respectively. The significance of process parameters specifically; the flow rate and the inlet temperature on microparticles surface integrity were observed, and optimized until encapsulating efficiency reached 72.37%. The scanning electron microscopical examination of the optimized microparticles illustrate uniform smooth surface spheres entrapping the drug in an amorphous state as proved through Differential Scanning Calorimetry (DSC) and Fourier Transfer Infrared (FTIR) studies. The in-vivo evaluation demonstrated a 5-fold enhancement in pravastatin bioavailability compared to the marketed product. The results provided evidence for the significance of spray-dried pH-sensitive microparticles as a promising carrier for pravastatin, decreasing its acid liability, and improving its bioavailability.

Implications of cerebrovascular ATP-binding cassette transporter G1 (ABCG1) and apolipoprotein M in cholesterol transport at the blood-brain barrier

Impaired cholesterol/lipoprotein metabolism is linked to neurodegenerative diseases such as Alzheimer's disease (AD). Cerebral cholesterol homeostasis is maintained by the highly efficient blood-brain barrier (BBB) and flux of the oxysterols 24(S)-hydroxycholesterol and 27-hydroxycholesterol, potent liver-X-receptor (LXR) activators. HDL and their apolipoproteins are crucial for cerebral lipid transfer, and loss of ATP binding cassette transporters (ABC)G1 and G4 results in toxic accumulation of oxysterols in the brain. The HDL-associated apolipoprotein (apo)M is positively correlated with pre-β HDL formation in plasma; its presence and function in the brain was thus far unknown. Using an in vitro model of the BBB, we examined expression, regulation, and functions of ABCG1, ABCG4, and apoM in primary porcine brain capillary endothelial cells (pBCEC). RT Q-PCR analyses and immunoblotting revealed that in addition to ABCA1 and scavenger receptor, class B, type I (SR-BI), pBCEC express high levels of ABCG1, which was up-regulated by LXR activation. Immunofluorescent staining, site-specific biotinylation and immunoprecipitation revealed that ABCG1 is localized both to early and late endosomes and on apical and basolateral plasma membranes. Using siRNA interference to silence ABCG1 (by 50%) reduced HDL-mediated [³H]-cholesterol efflux (by 50%) but did not reduce [³H]-24(S)-hydroxycholesterol efflux. In addition to apoA-I, pBCEC express and secrete apoM mainly to the basolateral (brain) compartment. HDL enhanced expression and secretion of apoM by pBCEC, apoM-enriched HDL promoted cellular cholesterol efflux more efficiently than apoM-free HDL, while apoM-silencing diminished cellular cholesterol release. We suggest that ABCG1 and apoM are centrally involved in regulation of cholesterol metabolism/turnover at the BBB.

Statins inhibit blastocyst formation by preventing geranylgeranylation

STUDY HYPOTHESIS

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase of the mevalonate pathway and prescription drugs that treat hypercholesterolemia, compromise preimplantation mouse development via modulation of HIPPO signaling.

STUDY FINDING

HMG-CoA reductase activity is required for trophectoderm specification, namely blastocyst cavity formation and Yes-associated protein (YAP) nuclear localization, through the production of isoprenoid geranylgeranyl pyrophosphate (GGPP) and the action of geranylgeranyl transferase.

WHAT IS KNOWN ALREADY

Previous studies have shown that treatment of mouse embryos with mevastatin prevents blastocyst formation, but how HMG-CoA reductase is involved in preimplantation development is unknown. HIPPO signaling regulates specification of the trophectoderm lineage of the mouse blastocyst by controlling the nuclear localization of YAP. In human cell lines, the mevalonate pathway regulates YAP to mediate self-renewal and survival through geranylgeranylation of RHO proteins. These studies suggest that in preimplantation development, statins may act through HIPPO pathway to interfere with trophectoderm specification and thereby inhibit blastocyst formation.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

Eight-cell stage (E2.5) mouse embryos were treated in hanging drop culture with chemical agents, namely statins (lovastatin, atorvastatin, cerivastatin and pravastatin), mevalonic acid (MVA), cholesterol, squalene, farnesyl pyrophosphate (FPP), geranylgeranyl pyrophosphate (GGPP), geranylgeranyltransferase inhibitor GGTI-298, RHO inhibitor I, and squalene synthase inhibitor YM-53601, up to the late blastocyst stage (E4.5). Efficiency of blastocyst formation was assessed based on gross morphology and the measurement of the cavity size using an image analysis software. Effects on cell lineages and HIPPO signaling were analyzed using immunohistochemistry with confocal microscopy based on the expression patterns of the lineage-specific markers and the nuclear accumulation of YAP. Effects on cell lineages were also examined by quantitative RT-PCR based on the transcript levels of the lineage-specific marker genes. Data were analyzed using one-way ANOVA and two-sample t-test.

MAIN RESULTS AND THE ROLE OF CHANCE

All four statins examined inhibited blastocyst formation. The adverse impact of statins was rescued by supplementation of MVA (P < 0.01) or GGPP (P < 0.01) but not squalene nor cholesterol. Blastocyst formation was also prevented by GGTI-298 (P < 0.01). These results indicate that HMG-CoA reductase activity is required for blastocyst formation mainly through the production of GGPP but not cholesterol. Inhibition of RHO proteins, known targets of geranylgeranylation, impaired blastocyst formation, which was not reversed by GGPP supplementation. Nuclear localization of YAP was diminished by statin treatment but fully restored by supplementation of MVA (P < 0.01) or GGPP (P < 0.01). This suggests that HIPPO signaling is regulated by GGPP-dependent mechanisms, possibly geranylgeranylation of RHO, to enable trophectoderm formation. YM-53601 prevented blastocyst formation (P < 0.01), but its adverse impact was not rescued by supplementation of squalene or cholesterol, suggesting that squalene synthesis inhibition was not the cause of blastocyst defects.

LIMITATIONS, REASONS FOR CAUTION

Analyses were conducted on embryos cultured ex vivo, but they enable the determination of specific concentrations that impair embryo development which can be compared with drug concentrations in the reproductive tract when testing in vivo impact of statins through animal experimentations. Also, analyses were conducted in only one species, the mouse. Epidemiological studies on the effects of various types of statins on the fertility of women are necessary.

WIDER IMPLICATIONS OF THE FINDINGS

Our study reveals how the mevalonate pathway is required for blastocyst formation and intersects with HIPPO pathway to provide a mechanistic basis for the embryotoxic effect of statins. This bears relevance for women who are taking statins while trying to conceive, since statins have potential to prevent the conceptus from reaching the blastocyst stage and to cause early conceptus demise.

LARGE SCALE DATA

Not applicable.

STUDY FUNDING AND COMPETING INTERESTS

This study was supported by grants from the George F. Straub Trust of the Hawaii Community Foundation (13ADVC-60315 to V.B.A.) and the National Institutes of Health, USA (P20GM103457 to V.B.A.). The authors have no conflict of interest to declare.

Molecular mechanisms underlying the effects of statins in the central nervous system

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, commonly referred to as statins, are widely used in the treatment of dyslipidaemia, in addition to providing primary and secondary prevention against cardiovascular disease and stroke. Statins’ effects on the central nervous system (CNS), particularly on cognition and neurological disorders such as stroke and multiple sclerosis, have received increasing attention in recent years, both within the scientific community and in the media. Current understanding of statins’ effects is limited by a lack of mechanism-based studies, as well as the assumption that all statins have the same pharmacological effect in the central nervous system. This review aims to provide an updated discussion on the molecular mechanisms contributing to statins’ possible effects on cognitive function, neurodegenerative disease, and various neurological disorders such as stroke, epilepsy, depression and CNS cancers. Additionally, the pharmacokinetic differences between statins and how these may result in statin-specific neurological effects are also discussed.

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.

Effects of pravastatin on the pharmacokinetic parameters of nimodipine after oral and intravenous administration in rats: possible role of CYP3A4 inhibition by pravastatin

Objective:

The aim of this study was to investigate the effects of pravastatin on the pharmacokinetics of nimodipine in rats.

Materials and Methods:

The effect of pravastatin on P-glycoprotein (P-gp) and cytochrome P450 (CYP) 3A4 activity was evaluated. Nimodipine was administered to rats intravenously (3 mg/kg) and orally (12 mg/kg) with pravastatin (0.3 and 1 mg/kg).

Results:

Pravastatin inhibited CYP3A4 enzyme activity in a concentration-dependent manner with a 50% inhibition concentration (IC₅₀) of 14 µM. Compared with the oral control group, the area under the plasma concentration-time curve (AUC_0-∞) of nimodipine was increased significantly. Consequently, the absolute bioavailability (AB) of nimodipine with pravastatin (1 mg/kg) was 31.1%, which was significantly enhanced compared with the oral control group. Moreover, the relative bioavailability (RB) of nimodipine was 1.12- to 1.31-fold greater than that of the control group.

Conclusions:

The enhanced oral bioavailability of nimodipine might be mainly due to inhibition of the CYP3A-mediated metabolism of nimodipine in the small intestine and/or in the liver and due to reduction of the total body clearance rather than both to inhibition of the P-gp efflux transporter in the small intestine and reduction of renal elimination of nimodipine by pravastatin. The increase in the oral bioavailability of nimodipine with pravastatin should be taken into consideration of potential drug interactions between nimodipine and pravastatin.

Assaying embryotoxicity in the test tube: current limitations of the embryonic stem cell test (EST) challenging its applicability domain

Testing for embryotoxicity in vitro is an attractive alternative to animal experimentation. The embryonic stem cell test (EST) is such a method, and it has been formally validated by the European Centre for the Validation of Alternative Methods. A number of recent studies have underscored the potential of this method. However, the EST performed well below the 78% accuracy expected from the validation study using a new set of chemicals and pharmaceutical compounds, and also of toxicity criteria, tested to enlarge the database of the validated EST as part of the Work Package III of the ReProTect Project funded within the 6th Framework Programme of the European Union. To assess the performance and applicability domain of the EST we present a detailed review of the substances and their effects in the EST being nitrofen, ochratoxin A, D-penicillamine, methylazoxymethanol, lovastatin, papaverine, warfarin, β-aminopropionitrile, dinoseb, furosemide, doxylamine, pravastatin, and metoclopramide. By delineation of the molecular mechanisms of the substances we identify six categories of reasons for misclassifications. Some of these limitations might also affect other in vitro methods assessing embryotoxicity. Substances that fall into these categories need to be included in future validation sets and in validation guidelines for embryotoxicity testing. Most importantly, we suggest conceivable improvements and additions to the EST which will resolve most of the limitations.

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.

Pharmacological actions of statins: a critical appraisal in the management of cancer

Statins, among the most commonly prescribed drugs worldwide, are cholesterol-lowering agents used to manage and prevent cardiovascular and coronary heart diseases. Recently, a multifaceted action in different physiological and pathological conditions has been also proposed for statins, beyond anti-inflammation and neuroprotection. Statins have been shown to act through cholesterol-dependent and -independent mechanisms and are able to affect several tissue functions and modulate specific signal transduction pathways that could account for statin pleiotropic effects. Typically, statins are prescribed in middle-aged or elderly patients in a therapeutic regimen covering a long life span during which metabolic processes, aging, and concomitant novel diseases, including cancer, could occur. In this context, safety, toxicity, interaction with other drugs, and the state of health have to be taken into account in subjects treated with statins. Some evidence has shown a dichotomous effect of statins with either cancer-inhibiting or -promoting effects. To date, clinical trials failed to demonstrate a reduced cancer occurrence in statin users and no sufficient data are available to define the long-term effects of statin use over a period of 10 years. Moreover, results from clinical trials performed to evaluate the therapeutic efficacy of statins in cancer did not suggest statin use as chemotherapeutic or adjuvant agents. Here, we reviewed the pharmacology of the statins, providing a comprehensive update of the current knowledge of their effects on tissues, biological processes, and pathological conditions, and we dissected the disappointing evidence on the possible future use of statin-based drugs in cancer therapy.

Paradoxical decrease in HDL-cholesterol and apolipoprotein A1 with simvastatin and atorvastatin in a patient with type 2 diabetes

Statins are agents widely used to lower LDL-cholesterol (LDL-C) in primary and secondary prevention of coronary heart disease. The five statins available in the UK (simvastatin, pravastatin, fluvastatin, atorvastatin and rosuvastatin) differ in many of their pharmacologic properties. In addition to lowering LDL-C, statins also increase HDL-cholesterol (HDL-C) moderately. There have been rare reports of significant HDL-C decreases in patients commenced on fibrates and when thiazolidinediones are added to fibrates. This is known as a 'paradoxical HDL-C decrease' as both groups of agents usually increase HDL-C. This phenomenon has never been clearly documented following statin therapy. We now describe a patient with type 2 diabetes who showed this paradoxical fall in HDL-C (baseline HDL-C: 1.8 mmol/L; on simvastatin 40 mg HDL-C 0.6 mmol/L; on atorvastatin 20 mg HDL-C 0.9 mmol/L) with a similar decrease in apolipoprotein A1. No similar decrease was observed with pravastatin and rosuvastatin therapy. This phenomenon appeared to be associated with statin treatment and not a statin/fibrate combination. Our patient clearly demonstrated a paradoxical HDL-C fall with simvastatin and atorvastatin, but not pravastatin or rosuvastatin. Simvastatin and atorvastatin share many pharmacokinetic properties such as lipophilicity while pravastatin and rosuvastatin are relatively hydrophilic and are not metabolized by cytochrome P450 3A4. However, these characteristics do not explain the dramatic reductions in HDL-C observed.

Pravastatin treatment causes a shift in the balance of hippocampal neurotransmitter binding densities towards inhibition

Since pravastatin, a HMG-CoA reductase inhibitor, has recently been shown to reduce infarct volumes and glutamate release in a rat model of ischemic stroke, the aim of the present study was to investigate whether this neuroprotective effect may be due to a modulation of excitatory and inhibitory neurotransmitter receptors. Therefore, Wistar rats were treated six times in 4 days with pravastatin or saline and allowed to survive for 6 hours or 5 days (n=10 per time point and group), respectively. Using quantitative receptor autoradiography, ligand binding densities of [(3)H]MK-801, [(3)H]AMPA, and [(3)H]muscimol for labeling of NMDA, AMPA, and GABA(A) receptors were analyzed in sensorimotor cortices Par1 and Par2, the striatum, and the hippocampus. Statin therapy induced complex alterations of ligand binding densities in different brain regions. Labeling of NMDA receptors was significantly increased in Par2, both after 6 hours and 5 days, respectively. Within the striatum, AMPA as well as GABA(A) receptor binding values were significantly increased on day 5. Furthermore, a marked and significant increase of [(3)H]muscimol ligand binding to GABA(A) receptors throughout all hippocampal subfields was seen after 6 hours. This complexity could easily be unraveled when focusing on the balance between excitatory glutamate and inhibitory GABA(A) receptors, in which case only the increase of hippocampal [(3)H]muscimol ligand binding 6 hours after the first application of pravastatin was accompanied by a net shift towards inhibition. Consequently, our data suggest an additional regulatory pathway induced by statins, namely modification of the abundance of excitatory and inhibitory neurotransmitter receptors.

Simvastatin inhibits the activation of p21ras and prevents the loss of dopaminergic neurons in a mouse model of Parkinson's disease

Parkinson's disease (PD) is second only to Alzheimer's disease as the most common devastating human neurodegenerative disorder. Despite intense investigation, no interdictive therapy is available for PD. We investigated whether simvastatin, a Food and Drug Administration-approved cholesterol-lowering drug, could protect against nigrostriatal degeneration after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication to model PD in mice. First, MPP(+) induced the activation of p21(ras) and nuclear factor-kappaB (NF-kappaB) in mouse microglial cells. Inhibition of MPP(+)-induced activation of NF-kappaB by Deltap21(ras), a dominant-negative mutant of p21(ras), supported the involvement of p21(ras) in MPP(+)-induced microglial activation of NF-kappaB. Interestingly, simvastatin attenuated activation of both p21(ras) and NF-kappaB in MPP(+)-stimulated microglial cells. Consistently, we found a very rapid activation of p21(ras) in vivo in the substantia nigra pars compacta of MPTP-intoxicated mice. However, after oral administration, simvastatin entered into the nigra, reduced nigral activation of p21(ras), attenuated nigral activation of NF-kappaB, inhibited nigral expression of proinflammatory molecules, and suppressed nigral activation of glial cells. These findings paralleled dopaminergic neuronal protection, normalized striatal neurotransmitters, and improved motor functions in MPTP-intoxicated mice. Similarly, pravastatin, another cholesterol-lowering drug, suppressed microglial inflammatory responses and protected dopaminergic neurons in MPTP-intoxicated mice, but at levels less than simvastatin. Furthermore, both the statins administered 2 d after initiation of the disease were still capable of inhibiting the demise of dopaminergic neurons and concomitant loss of neurotransmitters, suggesting that statins are capable of slowing down the progression of neuronal loss in the MPTP mouse model. Therefore, we conclude that statins may be of therapeutic benefit for PD patients.

Statins improve visual field alterations related to hypercholesterolemia

OBJECTIVE

To determine whether lipid-lowering treatment with diet or statins would provide beneficial effects on visual field alterations associated with hypercholesterolemia.

METHODS

180 subjects with hypercholesterolemia were randomly assigned to a low fat diet (diet group) or to a low fat diet plus 40 mg/day of pravastatin (pravastatin group). At the beginning of the study and 6 months after the assigned treatment, all subjects underwent a computerized perimetry test and a determination of plasma concentration of glucose, total cholesterol, LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C) and triglycerides.

RESULTS

At 6 months, both groups showed a significant decrease in total cholesterol, LDL-C and triglycerides compared to basal values, and a significant increase in the HDL-C. The pravastatin group had a significantly greater reduction in total cholesterol (-85+/-21 mg/dl) and LDL-C (-86+/-23 mg/dl) than the diet group (-28+/-9 and -28+/-10mg/dl, respectively). All perimetry parameters improved in both groups after the intervention period, although the improvement was greater in the pravastatin group. Using a general linear model, a significant effect of treatment with pravastatin compared to diet was observed in the improvement of all the perimetry parameters, whereas the change in LDL-C concentrations only had a significant effect on the improvement of one of them.

CONCLUSION

In subjects with hypercholesterolemia, the decrease of blood lipids improves visual field parameters. The major beneficial effect noted with pravastatin, compared to diet, suggests that this effect could be due to the lipid-lowering and pleiotropic actions.

Statin treatment of adult human glial progenitors induces PPAR gamma-mediated oligodendrocytic differentiation

The statins have been proposed as possible therapeutic agents for a variety of autoimmune disorders, including multiple sclerosis. In a genomic screen, we found that glial progenitor cells (GPCs) of the adult human white matter expressed significant levels of the principal statin target, HMG-CoA reductase, as well as additional downstream members of the sterol synthesis pathway. We therefore asked if statin treatment might influence the differentiated fate of adult glial progenitor cells. To assess the functional importance of the sterol synthesis pathway to adult human glial progenitors, we used simvastatin or pravastatin to inhibit HMG-CoA reductase, and then assessed the phenotypic differentiation of the progenitors, as well as the molecular concomitants thereof. We found that both statins induced a dose-dependent induction of oligodendrocyte phenotype, and concomitant reduction in progenitor number. Oligodendrocyte commitment was associated with induction of the sterol-regulated nuclear co-receptor PPARgamma, and could be blocked by the specific PPARgamma antagonist GW9662. Thus, statins may promote oligodendrocyte lineage commitment by parenchymal glial progenitor cells; this might reduce the available progenitor pool, and hence degrade the long-term regenerative competence of the adult white matter.

Gemfibrozil and its glucuronide inhibit the hepatic uptake of pravastatin mediated by OATP1B1

When pravastatin (40 mg/day) was co-administered with gemfibrozil (600 mg, b.i.d., 3 days) to man, the AUC of pravastatin increased approximately 2-fold. We have clarified that OATP1B1 is a key determinant of the hepatic uptake of pravastatin in humans. Thus, we hypothesized that gemfibrozil and the main plasma metabolites, a glucuronide (gem-glu) and a carboxylic acid metabolite (gem-M3), might inhibit the hepatic uptake of pravastatin and lead to the elevation of the plasma concentration of pravastatin. Gemfibrozil and gem-glu inhibited the uptake of (14)C-pravastatin by human hepatocytes with K(i) values of 31.7 microM and 15.7 microM, respectively and also inhibited pravastatin uptake by OATP1B1-expressing Xenopus laevis oocytes with K(i) values of 15.1 microM and 7.6 microM. Additionally, we examined the biliary transport of pravastatin and demonstrated that pravastatin was transported by MRP2 using both human canalicular membrane vesicles (hCMVs) and human MRP2-expressing vesicles. However, gemfibrozil, gem-glu and gem-M3 did not affect the biliary transport of pravastatin by MRP2. Considering the plasma concentrations of gemfibrozil and gem-glu in humans, the inhibition of OATP1B1-mediated hepatic uptake of pravastatin by gem-glu would contribute, at least in part, to the elevation of plasma concentration of pravastatin by the concomitant use of gemfibrozil.

Inhibition of human organic anion transporter 3 mediated pravastatin transport by gemfibrozil and the metabolites in humans

Coadministration of gemfibrozil (600 mg, b.i.d., 3 days) with pravastatin (40 mg/day) decreased the renal clearance of pravastatin by approximately 40% in healthy volunteers. To investigate the mechanism of this drug-drug interaction in the renal excretion process, we undertook an uptake study of pravastatin using human organic anion transporters (hOATs)-expressing S2 cells. hOAT3 and hOAT4 transported pravastatin in a saturatable manner with Michaelis--Menten constants of 27.7 microM and 257 microM respectively. On the other hand, hOAT1 and hOAT2 did not transport pravastatin. Gemfibrozil and its glucuronide and carboxylic metabolite forms inhibited the uptake of pravastatin by hOAT3 with IC(50) values of 6.8 microM, 19.7 microM and 5.4 microM, respectively. Considering the plasma concentrations of gemfibrozil and its metabolites in humans, the inhibition of hOAT3-mediated pravastatin transport by gemfibrozil and its metabolites would lead to a decrease in the renal clearance of pravastatin in clinical settings.

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.

Prescription des statines en cas d’insuffisance rénale

BACKGROUND

Chronic kidney disease (CKD) is extremely common in adults, although often undiagnosed and thus untreated. Cardiovascular disease is the leading cause of death among patients with CKD and reducing its risk in this population is an important priority. Dyslipidemia is almost always present when proteinuria is above 3 gr/24 hours. Roughly two thirds of all patients with end-stage renal failure and kidney transplants suffer from dyslipidemia and should receive lipid-lowering therapy, as suggested by recent Afssaps (French drug agency) and NKF-K/DOQI (National Kidney Foundation-Kidney Disease Outcomes Quality Initiative) guidelines. We reviewed recent studies on efficacy, tolerability and prescription recommendations of statins in CKD and renal transplant patients.

METHODS

We searched Medline, the international medical database, to conduct a systematic review of the literature on the efficacy and tolerability of statins in CKD and renal transplant patients and on specific recommendations for dosage adjustments in this population.

RESULTS

The efficacy of statins in decreasing total cholesterol and LDL-cholesterol levels in dialysis and renal transplant patients is similar to that in the general population. On the other hand, large-scale randomized clinical trials among CKD (4D) and renal transplant (ALERT) patients do not demonstrate that statins significantly decrease rates of cardiovascular disease. They have a beneficial effect on proteinuria and lower the rate of kidney function deterioration in patients with dyslipidemia. Early introduction of a statin in transplant patients did not lead to improved kidney function or prevent loss of the graft. Although most statins are not excreted by the kidneys, the dosage of some must be adapted in CKD patients because of pharmacokinetic modifications induced by renal impairment.

CONCLUSION

Statins at appropriately adapted doses have the same efficacy in CKD patients as in subjects with normal kidney function, and tolerance is not a problem. Their effectiveness in cardiovascular prevention in this population has not been demonstrated to date. Results about statin-induced kidney protection are encouraging but further and more specific studies are needed.

Simvastatin regulates oligodendroglial process dynamics and survival

Simvastatin, a lipophilic statin that crosses the blood-brain barrier, is being evaluated as a potential therapy for multiple sclerosis (MS) due to its anti-inflammatory properties. We assessed the effects of simvastatin on cultures of rat newborn and human fetal oligodendrocyte progenitor cells (OPCs) and human adult mature oligodendrocytes (OLGs) with respect to cellular events pertaining to myelin maintenance and repair. Short-term simvastatin treatment of OPCs (1 day) induced robust process extension, enhanced differentiation to a mature phenotype, and decreased spontaneous migration. These effects were reversed by isoprenoid products and mimicked with an inhibitor of Rho kinase (ROCK), the downstream effector of the isoprenylated protein RhoA GTPase. Prolonged treatment (2 days) caused process retraction that was rescued by cholesterol, and increased cell death (4 days) partially rescued by either cholesterol or isoprenoid co-treatment. In comparison, simvastatin treatment of human mature OLGs required a longer initial time course (2 days) to induce significant process outgrowth, mimicked by inhibiting ROCK. Prolonged treatment of mature OLGs was associated with process retraction (6 days) and increased cell death (8 days). Human-derived OPCs and mature OLGs demonstrated an increased sensitivity to simvastatin relative to the rodent cells, responding to nanomolar versus micromolar concentrations. Our findings indicate the importance of considering the short- and long-term effects of systemic immunomodulatory therapies on neural cells affected by the MS disease process. (c) 2006 Wiley-Liss, Inc.

Effects of pravastatin on the in vitro phagocytic function and hydrogen peroxide production by monocytes of healthy individuals

Macrophages play a part in pathogenesis of atherosclerosis, oxidizing LDL-cholesterol and transforming themselves in foam cells and producing free radicals of oxygen that may also oxidize LDL-cholesterol. HMG-CoA reductase inhibitors are very efficient in long-term control of atherogenesis acting by different mechanisms not fully established. Thus, we investigated the in vitro influence of pravastatin on phagocytosis and hydrogen peroxide production by monocytes of healthy individuals. Phagocytosis of Saccharomyces erevisiae by peripheral blood monocytes of 20 healthy individuals was assessed in the absence or presence of pravastatin. Hydrogen peroxide production was assessed based on the horseradish peroxidase-dependent oxidation of phenol red method. Pravastatin had no influence on phagocytosis through scavenger receptors, while it decreased by 20% the mean+/-SD phagocytic index of monocytes through complement receptors, from 141+/-77 to 113+/-56 (p=0.017), due to a decrease in the number of particles ingested by monocytes, from 2.1+/-0.5 to 1.7+/-0.3 (p=0.003). This statin also decreased the baseline production of hydrogen peroxide, by 7.7%, from 0.098+/-0.013 to 0.091+/-0.013 (OD by 2x10(5) monocytes per hour) (p=0.025). Pravastatin was able to decrease the phagocytosis through complement receptors and caused a decrease in the production of hydrogen peroxide by monocytes. It is possible this statin may directly inhibit the development of atherosclerotic plaque and its instability dependent on phagocytosis and the presence of reactive species of oxygen.

Fluvastatin and lovastatin but not pravastatin induce neuroglial differentiation in human mesenchymal stem cells

Recent studies have shown that statins, the most potent inhibitors of 3-hydroxy-2-methylglutaryl coenzyme A (HMG-CoA) reductase, stimulate bone formation in vitro and in rodents by activating the expression of bone morphogenetic protein-2 (BMP-2), one of the most critical osteoblast differentiation-inducing factors. However, the effect of statins on mesenchymal stem cells (MSCs) is yet to be reported. The purpose of this study is to investigate the influence of fluvastatin, lovastatin, and pravastatin, three commonly prescribed lipid-lowering agents, on the proliferation and differentiation of human MSCs. To our surprise, even though fluvastatin and lovastatin effectively suppressed the growth of human MSCs, a neuroglia rather than osteoblast-like morphology was observed after treatment. Interestingly, such morphological change was inhibited by the co-addition of geranylgeranyl pyrophosphate (GGPP). Immunofluorescence staining with antibodies against neuron-, astrocyte-, as well as oligodendrocyte-specific markers confirmed the neuroglial identity of the differentiated cells. However, BMP-2 is unlikely to play a positive role in neuroglial differentiation of MSCs since its expression was down-regulated in fluvastatin-treated cells. Taken together, our results suggest that fluvastatin and lovastatin induce neuroglial differentiation of human MSCs and that these cholesterol-lowering agents might be used in conjunction with MSC transplantation in the future for treating neurological disorders and injuries.

Statins' dosage in patients with renal failure and cyclosporine drug-drug interactions in transplant recipient patients

Dyslipidemia is frequent in patients with renal failure and in transplant recipient patients. This lead to a wide use of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) in patients with impaired renal function or in patients treated with cyclosporine as post-transplantation immunosuppressive therapy. As a result, it is crucial for those patients' physicians to be aware of how to handle these drugs when renal function is impaired and/or when cyclosporine is co-administered. Most statins have an extensive hepatic elimination and the renal route is usually a minor elimination pathway. However, pharmacokinetic alterations have been described for some of these drugs in patients with renal insufficiency. Cyclosporine is a widely used immunosuppresive therapy in solid organ transplant patients and drug-drug interactions are likely to occur when statins and cyclosporine are administered together. Those interactions may theoretically result in increased statins and/or cyclosporine serum levels with potential muscle and/or renal toxicity. As a result, caution is warranted if concurrent administration is performed. In this review, we synthesized the data from the literature on (1) the pharmacokinetics and dosage adjustment of atorvastatin, fluvastatin, pravastatin, rosuvastatin, and simvastatin in patients with renal failure and (2) the potential drug-drug interactions between these drugs and cyclosporine in transplant recipient patients.

Chemical, pharmacokinetic and pharmacodynamic properties of statins: an update

Statins are the treatment of choice for the management of hypercholesterolaemia because of their proven efficacy and safety profile. They also have an increasing role in managing cardiovascular risk in patients with relatively normal levels of plasma cholesterol. Although all statins share a common mechanism of action, they differ in terms of their chemical structures, pharmacokinetic profiles, and lipid-modifying efficacy. The chemical structures of statins govern their water solubility, which in turn influences their absorption, distribution, metabolism and excretion. Lovastatin, pravastatin and simvastatin are derived from fungal metabolites and have elimination half-lives of 1-3 h. Atorvastatin, cerivastatin (withdrawn from clinical use in 2001), fluvastatin, pitavastatin and rosuvastatin are fully synthetic compounds, with elimination half-lives ranging from 1 h for fluvastatin to 19 h for rosuvastatin. Atorvastatin, simvastatin, lovastatin, fluvastatin, cerivastatin and pitavastatin are relatively lipophilic compounds. Lipophilic statins are more susceptible to metabolism by the cytochrome P(450) system, except for pitavastatin, which undergoes limited metabolism via this pathway. Pravastatin and rosuvastatin are relatively hydrophilic and not significantly metabolized by cytochrome P(450) enzymes. All statins are selective for effect in the liver, largely because of efficient first-pass uptake; passive diffusion through hepatocyte cell membranes is primarily responsible for hepatic uptake of lipophilic statins, while hydrophilic agents are taken up by active carrier-mediated processes. Pravastatin and rosuvastatin show greater hepatoselectivity than lipophilic agents, as well as a reduced potential for uptake by peripheral cells. The bioavailability of the statins differs greatly, from 5% for lovastatin and simvastatin to 60% or greater for cerivastatin and pitavastatin. Clinical studies have demonstrated rosuvastatin to be the most effective for reducing low-density lipoprotein cholesterol, followed by atorvastatin, simvastatin and pravastatin. As a class, statins are generally well tolerated and serious adverse events, including muscle toxicity leading to rhabdomyolysis, are rare. Consideration of the differences between the statins helps to provide a rational basis for their use in clinical practice.

Pharmacokinetic properties of pravastatin in Mexicans: An open-label study in healthy adult volunteers

BACKGROUND

The pharmacokinetic properties of pravastatin, particularlyAUC and Cmax, are variable by population. A description of the pharmacokinetic properties of pravastatin in Mexican mestizos was not found in a search of MEDLINE/PubMed (key terms: pravastatin, Mexican, and pharmacokinetics; years: 1966-2005). Because Mexicans and Japanese have common ancestors (Mongoloid group), they also have a common gene pool. This gene pool was modified by genetic "bottlenecks" that occurred when these populations migrated to the Americas and when the Mexican population mixed with the Spanish population during the 16th and 17th centuries. Previous studies in Japanese subjects showed 5 main mutations on the hepatic drug transporter OATP-C, resulting in higher Cmax and AUC values compared with whites. In the Japanese population, the rates of expression of the (*) 1b and (*) 15 alleles were 46% and 15%, respectively.

OBJECTIVE

The aim of this study was to evaluate the pharmacokinetic propertiesof pravastatin in healthy Mexican mestizo volunteers and to compare them with those in white and Japanese populations described in the literature.

METHODS

This open-label, uncontrolled pilot study of the pharmacokineticproperties of pravastatin was conducted at the Division of Pharmacology, Center for Research and Advanced Studies, Mexico City, Mexico. Healthy, adult, Mexican volunteers received a single dose of pravastatin 10 mg PO (tablet). High-performance liquid chromatography was used to determine plasma pravastatin concentrations between 15 minutes and 12 hours after dosing.

RESULTS

Twenty-four subjects (15 women, 9 men; mean age, 30.6 years)participated in the study. The mean (SD) Cmax was 9.5 (2.4) ng/mL; Tmax, 0.8 (0.3) hours; AUC0-∞ 35.7 (19.7) ng/mL - h; t1/2, 2.7 (1.1) hours; and mean residence time, 3.1 (1.1) hours. One volunteer (4%) had an AUC value that differed substantially from the rest of the study population, producing a bimodal distribution of the pharmacokinetic parameters. No adverse events were observed or reported during the trial.

CONCLUSIONS

In this small pilot study of the pharmacokinetic properties of pravastatin in Mexican mestizos, AUC was not statistically significantly different from previous studies, either in a white or Japanese population. However, we did not find the high values reported for Cmax in some Japanese subjects carrying recently reported mutations on the pravastatin transporter.

Cholesterol in neurologic disorders of the elderly: stroke and Alzheimer’s disease

Mechanisms for the regulation of intracellular cholesterol levels in various types of brain and vascular cells are of considerable importance in our understanding of the pathogenesis of a variety of diseases, particularly atherosclerosis and Alzheimer's disease (AD). It is increasingly clear that conversion of brain cholesterol into 24-hydroxycholesterol and its subsequent release into the periphery is important for the maintenance of brain cholesterol homeostasis. Recent studies have shown elevated plasma concentrations of 24-hydroxycholesterol in patients with AD and vascular dementia, suggesting increased brain cholesterol turnover during neurodegeneration. The oxygenases involved in the degradation and excretion of cholesterol, including the cholesterol 24-hydroxylase and the 27-hydroxylase, are enzymes of the cytochrome P-450 family. This review focuses on the newly recognized importance of cholesterol and its oxygenated metabolites in the pathogenesis of ischemic stroke and AD. The reduction in stroke and AD risk in patients treated with cholesterol-lowering statins is also discussed.

Pharmacokinetic parameter prediction from drug structure using artificial neural networks

Simple methods for determining the human pharmacokinetics of known and unknown drug-like compounds is a much sought-after goal in the pharmaceutical industry. The current study made use of artificial neural networks (ANNs) for the prediction of clearances, fraction bound to plasma proteins, and volume of distribution of a series of structurally diverse compounds. A number of theoretical descriptors were generated from the drug structures and both automated and manual pruning were used to derive optimal subsets of descriptors for quantitative structure-pharmacokinetic relationship models. Models were trained on one set of compounds and validated with another. Absolute predicted ability was evaluated using a further independent test set of compounds. Correlations for test compounds ranged from 0.855 to 0.992. Predicted values agreed closely with experimental values for total clearance, renal clearance, and volume of distribution, while predictions for protein binding were encouraging. The combination of descriptor generation, ANNs, and the speed and success of this technique compared with conventional methods shows strong potential for use in pharmaceutical product development.

[Establishment and effect of the drug safety management monitoring system]

Early detection and early treatment of adverse drug reactions have recently become more important. It is natural that physicians should treat adverse drug reactions carefully, but it is also important to establish a system for their early systematic detection and treatment. Therefore, by comparing current data with that preserved in our clinical laboratory's data management registry and identifying values significantly different from earlier values, we established a screening system for any condition which may have a possible relationship with drugs and feeds back the results to the physician(s) in charge (drug safety management monitoring system). The effectiveness of the system was then evaluated. The subjects were outpatients who visited the Diabetes Endocrine Metabolism Center of our hospital during a six-month period. Cases where the possibility of a relationship between abnormal changes of laboratory data and drugs was not ruled out were reported to the attending physician using a drug safety monitoring report form. In 14 of 34 cases reported, a relationship with drugs could not be ruled out. Two of these 14 cases were reported to the Ministry of Health, Labour and Welfare because they were serious. Therefore, it was concluded that this system was useful for early detection of adverse reactions.

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.

Combination lipid-lowering therapy with statins: safety issues in the postcerivastatin era

Combination lipid-altering regimens represent an emerging clinical paradigm to meet increasingly stringent consensus lipoprotein targets for coronary prevention. This practice, together with escalating prevalences of coronary artery disease in certain ageing (western industrial) populations, polypharmacy in the elderly and the recent voluntary market withdrawal of cerivastatin, warrants a re-examination of the safety profiles of 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase inhibitors (i.e., statins). These agents are exceedingly well-tolerated in the vast majority of patients, very infrequently precipitating musculoskeletal symptoms and/or signs. Statins vary in their pharmacological profiles, leading to distinct levels of systemic exposure and capacities to penetrate skeletal myocytes. Pharmacokinetic interactions with certain agents increase the likelihood of statin-induced myopathy and, in exceedingly rare instances, potentially fatal rhabdomyolysis with myoglobinuria and renal failure. As with other medical decisions, the anticipated benefits of long-term statin therapy, with or without other lipid-altering agents, need to be weighed against the prospects of clinically significant drug interactions. In clinical trials and postmarketing surveillance, the two statins that are not metabolised by the cytochrome P450 3A4 system (fluvastatin and pravastatin) have exhibited very low propensities to elicit myopathy when combined with other agents. These agents should be considered initially when contemplating combination lipid-lowering regimens for coronary prevention.

The pleiotropic effects of HMG-CoA reductase inhibitors: their role in osteoporosis and dementia

HMG-CoA reductase is the rate-limiting enzyme for cholesterol synthesis and its inhibition exerts profound effects on cellular metabolism. Inhibitors of this enzyme are used in clinical practice to lower plasma cholesterol levels and are commonly collectively referred to as 'statins'. A number of in vitro, in vivo animal, and clinical studies suggest that properties of statins other than cholesterol lowering may be of biological importance. These diverse properties are often referred to as 'pleiotropic' and suggest that statins may affect a number of diseases of ageing. In this article we review the biological plausibility and clinical evidence of a role for statins in modulating two diseases of ageing: osteoporosis and dementia (including Alzheimer's disease). In both diseases, there is a sound cellular and laboratory basis for a plausible therapeutic effect of statins. In the case of osteoporosis, there are conflicting data regarding clinical benefit, with both negative and positive results reported. In particular, secondary analyses of randomised, controlled studies have shown no reduction of fracture risk by statins. In the case of dementia there are fewer clinical studies but there is clear anticipated benefit in macrovascular dementias attributable to statin-mediated reduction of the risk of stroke. Overall, there are a lack of prospective, placebo-controlled, randomised data testing statins and modulation of the risk of osteoporosis-related fracture or of clinical dementia, where these are primary outcomes. Until such data are available, the use of statins appears promising but cannot be recommended as a primary therapeutic modality for either condition.

Pravastatin

Pravastatin (Pravachol) is a competitive, reversible HMG-CoA reductase inhibitor that lowers serum cholesterol levels by inhibiting de novo cholesterol synthesis and has antiatherogenic effects that appear to be partially independent of its lipid-lowering effects. Pravastatin 10-40 mg/day produced significant reductions (vs baseline or placebo) in serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels in elderly patients (aged >or=60 or >or= 65 years) with hypercholesterolaemia or normal cholesterol levels. Serum triglyceride and high-density lipoprotein cholesterol levels also improved in some studies, but not in others. Coadministration of cholestyramine, another lipid-lowering agent, further enhanced the lipid-lowering effects of pravastatin in elderly patients. Data from the large, long-term (3-6 years) PROspective Study Of Pravastatin in the Elderly at Risk (PROSPER), Cholesterol And Recurrent Events trial (CARE) and Long term Intervention with Pravastatin in Ischaemic Disease (LIPID) trials demonstrated that pravastatin 40 mg/day reduces coronary events in elderly patients with hypercholesterolaemia or normal cholesterol levels, with or at high risk of developing coronary heart disease (CHD). In these trials, the incidence of death from CHD or the combined endpoint of death from CHD or nonfatal myocardial infarction was significantly lower in pravastatin than in placebo recipients. Pravastatin is well tolerated in the elderly, and adverse effects considered related to therapy are minimal. The most commonly occurring adverse events included gastrointestinal events, renal or genital system events, respiratory disorders, headaches and musculoskeletal pain.

CONCLUSION

Pravastatin effectively lowers serum TC and LDL-C levels and, as demonstrated in major clinical outcome trials, reduces coronary events in elderly patients with hypercholesterolaemia or normal cholesterol levels. Pravastatin is well tolerated and as such should be considered a first-line agents for primary or secondary prevention in older individuals with evident CHD or multiple risk factors for CHD.

Pharmacology of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins), including rosuvastatin and pitavastatin

Coronary heart disease (CHD) is the leading cause of morbidity and mortality in the Western world, with hypercholesterolemia as the major risk factor. The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors represent the most efficient drugsfor the treatment of hypercholesterolemia. They lower plasma cholesterol due to the inhibition of endogenous cholesterol synthesis in the liverand subsequent increased expression of low-density lipoprotein (LDL) receptors, resulting in an up-regulated catabolic rate for plasma LDL. The beneficial effect of statins on the incidence of CHD was clearly demonstrated in several large-scale clinical trials. Currently, five statins (atorvastatin, fluvastatin, lovastatin, pravastatin, and simvastatin) are available, and two novel compounds (pitavastatin, rosuvastatin) are undergoing clinical investigation. To point out potential mechanisms leading to increased toxicity and to compare the novel statins with the established ones, this article summarizes their pharmacological data since the prevalence of adverse events can be explained at least in part by their pharmacokinetic differences.

Pharmacokinetic-pharmacodynamic drug interactions with HMG-CoA reductase inhibitors

The HMG-CoA reductase inhibitors (statins) are effective in both the primary and secondary prevention of ischaemic heart disease. As a group, these drugs are well tolerated apart from two uncommon but potentially serious adverse effects: elevation of liver enzymes and skeletal muscle abnormalities, which range from benign myalgias to life-threatening rhabdomyolysis. Adverse effects with statins are frequently associated with drug interactions because of their long-term use in older patients who are likely to be exposed to polypharmacy. The recent withdrawal of cerivastatin as a result of deaths from rhabdomyolysis illustrates the clinical importance of such interactions. Drug interactions involving the statins may have either a pharmacodynamic or pharmacokinetic basis, or both. As these drugs are highly extracted by the liver, displacement interactions are of limited importance. The cytochrome P450 (CYP) enzyme system plays an important part in the metabolism of the statins, leading to clinically relevant interactions with other agents, particularly cyclosporin, erythromycin, itraconazole, ketoconazole and HIV protease inhibitors, that are also metabolised by this enzyme system. An additional complicating feature is that individual statins are metabolised to differing degrees, in some cases producing active metabolites. The CYP3A family metabolises lovastatin, simvastatin, atorvastatin and cerivastatin, whereas CYP2C9 metabolises fluvastatin. Cerivastatin is also metabolised by CYP2C8. Pravastatin is not significantly metabolised by the CYP system. In addition, the statins are substrates for P-glycoprotein, a drug transporter present in the small intestine that may influence their oral bioavailability. In clinical practice, the risk of a serious interaction causing myopathy is enhanced when statin metabolism is markedly inhibited. Thus, rhabdomyolysis has occurred following the coadministration of cyclosporin, a potent CYP3A4 and P-glycoprotein inhibitor, and lovastatin. Itraconazole has been shown to increase exposure to simvastatin and its active metabolite by at least 10-fold. Pharmacodynamically, there is an increased risk of myopathy when statins are coprescribed with fibrates or nicotinic acid. This occurs relatively infrequently, but is particularly associated with the combination of cerivastatin and gemfibrozil. Statins may also alter the concentrations of other drugs, such as warfarin or digoxin, leading to alterations in effect or a requirement for clinical monitoring. Knowledge of the pharmacokinetic properties of the statins should allow the avoidance of the majority of drug interactions. If concurrent therapy with known inhibitors of statin metabolism is necessary, the patient should be monitored for signs and symptoms of myopathy or rhabdomyolysis and the statin should be discontinued if necessary.

Simvastatin and lovastatin, but not pravastatin, interact with MDR1

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, pravastatin, was compared with simvastatin and lovastatin from the viewpoint of susceptibility to interaction with or via the multidrug transporter, MDR1 (P-glycoprotein). This was carried out using the MDR1-overexpressing cell line LLC-GA5-COL150, established by transfection of MDR1 cDNA into porcine kidney epithelial LLC-PK1 cells, and [3H]digoxin, which is a well-documented substrate for MDR1. Pravastatin, at 25-100 microM, had no effect on the transcellular transport of [3H]digoxin whereas simvastatin and lovastatin suppressed the basal-to-apical transport of [3H]digoxin and increased the apical-to-basal transport. It was suggested that recognition by MDR1 was due to the hydrophobicity. In conclusion, simvastatin and lovastatin are susceptible to interaction with or via MDR1, but pravastatin is not. This is important information when selecting the HMG-CoA reductase inhibitors for patients taking drugs that are MDR1 substrates.

Clinical pharmacokinetics of pravastatin: mechanisms of pharmacokinetic events

Pravastatin, one of the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) widely used in the management of hypercholesterolaemia, has unique pharmacokinetic characteristics among the members of this class. Many in vivo and in vitro human and animal studies suggest that active transport mechanisms are involved in the pharmacokinetics of pravastatin. The oral bioavailability of pravastatin is low because of incomplete absorption and a first-pass effect. The drug is rapidly absorbed from the upper part of the small intestine, probably via proton-coupled carrier-mediated transport, and then taken up by the liver by a sodium-independent bile acid transporter. About half of the pravastatin that reaches the liver via the portal vein is extracted by the liver, and this hepatic extraction is mainly attributed to biliary excretion which is performed by a primary active transport mechanism. The major metabolites are produced by chemical degradation in the stomach rather than by cytochrome P450-dependent metabolism in the liver. The intact drug and its metabolites are cleared through both hepatic and renal routes, and tubular secretion is a predominant mechanism in renal excretion. The dual routes of pravastatin elimination reduce the need for dosage adjustment if the function of either the liver or kidney is impaired, and also reduce the possibility of drug interactions compared with other statins. which are largely eliminated by metabolism. The lower protein binding than other statins weakens the tendency for displacement of highly protein-bound drugs. Although all statins show a hepatoselective disposition, the mechanism for pravastatin is different from that of the others. There is high uptake of pravastatin by the liver via an active transport mechanism, but not by other tissues because of its hydrophilicity, whereas the disposition characteristics of other statins result from high hepatic extraction because of high lipophilicity. These pharmacokinetic properties of pravastatin may be the result of the drug being given in the pharmacologically active open hydroxy acid form and the fact that its hydrophilicity is markedly higher than that of other statins. The nature of the pravastatin transporters, particularly in humans, remains unknown at present. Further mechanistic studies are required to establish the pharmacokinetic-pharmacodynamic relationships of pravastatin and to provide the optimal therapeutic efficacy for various types of patients with hypercholesterolaemia.

Cerivastatin: a review of its pharmacological properties and therapeutic efficacy in the management of hypercholesterolaemia

Cerivastatin is an HMG-CoA reductase inhibitor used for the treatment of patients with hypercholesterolaemia. The lipid-lowering efficacy of cerivastatin has been demonstrated in a number of large multicentre, randomised clinical trials. Earlier studies used cerivastatin at relatively low dosages of < or =0.3mg orally once daily, but more recent studies have focused on dosages of 0.4 or 0.8 mg/day currently recommended by the US Food and Drug Administration (FDA). Along with modest improvements in serum levels of triglycerides and high density lipoprotein (HDL)-cholesterol, cerivastatin 0.4 to 0.8 mg/day achieved marked reductions in serum levels of low density lipoprotein (LDL)-cholesterol (33.4 to 44.0%) and total cholesterol (23.0 to 30.8%). These ranges included results of a pivotal North American trial in almost 1000 patients with hypercholesterolaemia. In this 8-week study, US National Cholesterol Education Program (Adult Treatment Panel II) [NCEP] target levels for LDL-cholesterol were achieved in 84% of patients randomised to receive cerivastatin 0.8 mg/day, 73% of those treated with cerivastatin 0.4 mg/day and <10% of placebo recipients. Among patients with baseline serum LDL-cholesterol levels meeting NCEP guidelines for starting pharmacotherapy, 75% achieved target LDL-cholesterol levels with cerivastatin 0.8 mg/day. In 90% of all patients receiving cerivastatin 0.8 mg/day, LDL-cholesterol levels were reduced by 23.9 to 58.4% (6th to 95th percentile). Various subanalyses of clinical trials with cerivastatin indicate that the greatest lipid-lowering response can be expected in women and elderly patients. Cerivastatin is generally well tolerated and adverse events have usually been mild and transient. The overall incidence and nature of adverse events reported with cerivastatin in clinical trials was similar to that of placebo. The most frequent adverse events associated with cerivastatin were headache, GI disturbances, asthenia, pharyngitis and rhinitis. In the large pivotal trial, significant elevations in serum levels of creatine kinase and transaminases were reported in a small proportion of patients receiving cerivastatin but not in placebo recipients. As with other HMG-CoA reductase inhibitors, rare reports of myopathy and rhabdomyolysis have occurred with cerivastatin, although gemfibrozil or cyclosporin were administered concomitantly in most cases. Postmarketing surveillance studies in the US have been performed. In 3 mandated formulary switch conversion studies, cerivastatin was either equivalent or superior to other HMG-CoA reductase inhibitors, including atorvastatin, in reducing serum LDL-cholesterol levels or achieving NCEP target levels. Pharmacoeconomic data with cerivastatin are limited, but analyses conducted to date in the US and Italy suggest that cerivastatin compares favourably with other available HMG-CoA reductase inhibitors in terms of its cost per life-year gained.

CONCLUSION

Cerivastatin is a well tolerated and effective lipid-lowering agent for patients with hypercholesterolaemia. When given at dosages currently recommended by the FDA in the US, cerivastatin achieves marked reductions in serum levels of LDL-cholesterol, reaching NCEP target levels in the vast majority of patients. Thus, cerivastatin provides a useful (and potentially cost effective) alternative to other currently available HMG-CoA reductase inhibitors as a first-line agent for hypercholesterolaemia.

Quantitative determination of pravastatin and its biotransformation products in human serum by turbo ion spray LC/MS/MS

A sensitive, specific, accurate and reproducible analytical method was developed and validated to quantify pravastatin (Prav), pravastatin-d5 (Prav-d5), SQ-31906, SQ-31906-d5, and pravastatin lactone (Prav-Lac) in human serum samples. Serum samples (0.5 ml) were acidified and extracted by a solid-phase extraction procedure to isolate all five analytes from human serum. Sample extracts were reconstituted and analyzed by turbo ion spray liquid chromatography/tandem mass spectrometry (LC/MS/MS) in the positive ion mode. The total run time was 9 min between injections. The assay demonstrated a lower limit of quantitation (LLQ) of 0.5 ng/ml for all five analytes. The calibration curves were linear from 0.5 ng ml to 100 ng/ml for all five analytes. The coefficients of determination of all calibration curves were > or = 0.999. Precision and accuracy quality control (QC) samples were prepared at concentrations of 2, 30, 80, and 500 ng/ml for all analytes. The intra-assay and inter-assay precision calculated from QC samples were within 8%, for all analytes. The inter-assay accuracy calculated from QC samples was within 8% for all analytes. The extraction recoveries were > or = 90% for all analytes. Benchtop stability experiments in an ice-water bath ( < or = 10 degrees C) demonstrated that over time, Prav-Lac hydrolyzes to Prav in serum. Prav, Prav-d5, SQ-31906, and SQ-31906-d5 were stable under these conditions for up to 24 h. Hydrolysis was minimized by buffering the serum to pH 4.5 and maintaining the serum sample in an ice-water bath. All analytes were stable after three freeze/thaw cycles and in reconstitution solution after 1 week at 4 degrees C. Stability of all analytes in human serum was demonstrated after storage at -70 degrees C for 77 days. The benchtop (< or = 10 degrees C) stability of pooled study samples was also investigated and the results were comparable to those obtained from serum QC samples.