Drug interactions with statins

Clinical Evaluation of the Effect of Encorafenib on Bupropion, Rosuvastatin, and Coproporphyrin I and Considerations for Statin Coadministration

BACKGROUND AND OBJECTIVES

Encorafenib is a kinase inhibitor indicated for the treatment of patients with unresectable or metastatic melanoma or metastatic colorectal cancer, respectively, with selected BRAF V600 mutations. A clinical drug-drug interaction (DDI) study was designed to evaluate the effect of encorafenib on rosuvastatin, a sensitive substrate of OATP1B1/3 and breast cancer resistance protein (BCRP), and bupropion, a sensitive CYP2B6 substrate. Coproporphyrin I (CP-I), an endogenous substrate for OATP1B1, was measured in a separate study to deconvolute the mechanism of transporter DDI.

METHODS

DDI study participants received a single oral dose of rosuvastatin (10 mg) and bupropion (75 mg) on days - 7, 1, and 14 and continuous doses of encorafenib (450 mg QD) and binimetinib (45 mg BID) starting on day 1. The CP-I data were collected from participants in a phase 3 study who received encorafenib (300 mg QD) and cetuximab (400 mg/m2 initial dose, then 250 mg/m2 QW). Pharmacokinetic and pharmacodynamic analysis was performed using noncompartmental and compartmental methods.

RESULTS

Bupropion exposure was not increased, whereas rosuvastatin Cmax and area under the receiver operating characteristic curve (AUC) increased approximately 2.7 and 1.6-fold, respectively, following repeated doses of encorafenib and binimetinib. Increase in CP-I was minimal, suggesting that the primary effect of encorafenib on rosuvastatin is through BCRP. Categorization of statins on the basis of their metabolic and transporter profile suggests pravastatin would have the least potential for interaction when coadministered with encorafenib.

CONCLUSION

The results from these clinical studies suggest that encorafenib does not cause clinically relevant CYP2B6 induction or inhibition but is an inhibitor of BCRP and may also inhibit OATP1B1/3 to a lesser extent. Based on these results, it may be necessary to consider switching statins or reducing statin dosage accordingly for coadministration with encorafenib.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT03864042, registered 6 March 2019.

Statins-From Fungi to Pharmacy

Statins have been used in the treatment of hyperlipidemia, both as monotherapy and in combination therapy. Natural fermentation processes of fungi such as Monascus spp., Penicillium spp., Aspergillus terreus, and Pleurotus ostreatus have given rise to natural statins. Compactin (mevastatin), the original naturally occurring statin, is the primary biotransformation substrate in the manufacturing process of marketed drugs. Statins are classified into natural, semi-synthetic derivatives of natural statins, and synthetic ones. Synthetic statins differ from natural statins in their structural composition, with the only common feature being the HMG-CoA-like moiety responsible for suppressing HMG-CoA reductase. Statins do not differ significantly regarding their pleiotropic and adverse effects, but their characteristics depend on their pharmacokinetic parameters and chemical properties. This paper focuses on describing the processes of obtaining natural statins, detailing the pharmacokinetics of available statins, divided into natural and synthetic, and indicating their pleiotropic effects.

Effect of berberine on pharmacokinetics and pharmacodynamics of atorvastatin in hyperlipidemia rats

Atorvastatin, an effective lipid-lowering drug, could reduce the risks of morbidity and mortality of cardiovascular diseases. Patients with cardiovascular diseases often use atorvastatin along with berberine. Atorvastatin is the substrate of CYP3A4 and P-gp. However, berberine is the inhibitor. The combination might lead to DDIs. The aim of this study was to assess the effect of berberine on pharmacokinetics and pharmacodynamics of atorvastatin in rats.Plasma concentrations of atorvastatin with or without berberine were determined by HPLC. Pharmacokinetics parameters were calculated and used to evaluate pharmacokinetics interactions. The effect of berberine on pharmacodynamics of atorvastatin was investigated by detecting blood lipid, SOD, MDA, GSH-Px, AST, ALT, and liver histopathology.Cmax, tmax, and AUC0-t of atorvastatin in combination group significantly increased both in normal and model rats (p < 0.01). The increase of t1/2, AUC0-t in model rats was more significant than that in normal rats (p < 0.05). Pharmacodynamics indexes in treatment groups were significantly improved, especially combination group (p < 0.05). Moreover, it could be found that there is a significant recovery in liver histopathology.In conclusion, berberine could affect pharmacokinetics of atorvastatin, enhance lipid-lowering effect and improve liver injury in rats. More attention should be paid to plasma exposure in clinical to avoid adverse reactions.

Current and future options in cholesterol lowering treatments

The relative risk reduction of cardiovascular events is proportional to the absolute reduction in LDL-C levels, the primary target of therapy, no matter the way of reduction. During the last decades, the therapeutic regimens for reducing the LDL-C levels have been immerged and improved, with favorable effects on the atherosclerotic process and clinical benefits of various cardiovascular outcomes. From a practical view of point, this review is focusing only on the current available lipid lowering agents: statins, ezetimibe, anti PCSK9 monoclonal antibodies, the small interfering RNA (siRNA) agent, Inclisiran, and Bempedoic acid. The recent changes in lipid lowering regimens, including the early combination of lipid lowering agents and "Low LDL-C" levels <30 mg/dL for high/very high cardiovascular risk patients will also be discussed.

In vitro validation of an in vivo phenotyping drug cocktail for major drug transporters in humans

PURPOSE

Cocktails of transporter probe drugs are used in vivo to assess transporter activity and respective drug-drug interactions. An inhibitory effect of components on transporter activities should be ruled out. Here, for a clinically tested cocktail consisting of adefovir, digoxin, metformin, sitagliptin, and pitavastatin, inhibition of major transporters by individual probe substrates was investigated in vitro.

METHODS

Transporter transfected HEK293 cells were used in all evaluations. Cell-based assays were applied for uptake by human organic cation transporters 1/2 (hOCT1/2), organic anion transporters 1/3 (hOAT1/3), multidrug and toxin extrusion proteins 1/2K (hMATE1/2K), and organic anion transporter polypeptide 1B1 (hOATP1B1). For P-glycoprotein (hMDR1) a cell-based efflux assay was used whereas an inside-out vesicle-based assay was used for the bile salt export pump (hBSEP). All assays used standard substrates and established inhibitors (as positive controls). Inhibition experiments using clinically achievable concentrations of potential perpetrators at the relevant transporter expression site were carried out initially. If there was a significant effect, the inhibition potency (K_i) was studied in detail.

RESULTS

In the inhibition tests, only sitagliptin had an effect and reduced hOCT1- and hOCT2- mediated metformin uptake and hMATE2K mediated MPP⁺ uptake by more than 70%, 80%, and 30%, respectively. The ratios of unbound C_max (observed clinically) to K_i of sitagliptin were low with 0.009, 0.03, and 0.001 for hOCT1, hOCT2, and hMATE2K, respectively.

CONCLUSION

The inhibition of hOCT2 in vitro by sitagliptin is in agreement with the borderline inhibition of renal metformin elimination observed clinically, supporting a dose reduction of sitagliptin in the cocktail.

Hypercholesterolemia reduces the expression and function of hepatic drug metabolizing enzymes and transporters in rats

Hypercholesterolemia, one of the most common lipid metabolic diseases, may cause severe complications and even death. However, the effect of hypercholesterolemia on drug-metabolizing enzymes and transporters remains unclear. In this report, we established a rat model of diet-induced hypercholesterolemia. Quantitative real-time PCR and Western blot analysis were used to study the mRNA and protein expression of drug-metabolizing enzymes and transporters. The functions of these enzymes and transporters were evaluated by the cocktail assay. In hypercholesterolemic rats, the expression of phase I enzymes (CYP1A2, CYP2C11, CYP2E1, CYP3A1/2, CYP4A1 and FMO1/3) and phase II enzymes (UGT1A1/3, PROG, AZTG, SULT1A1, NAT1 and GSTT1) decreased. In addition, the mRNA levels of drug transporter Slco1a1/2, Slco1b2, Slc22a5, Abcc2, Abcb1a and Abcg2 decreased in rats with hypercholesterolemia, while Abcb1b and Abcc3 increased. The decreased expression of hepatic phase I and II enzymes and transporters may be caused by the changes of CAR, FXR, PXR, and Hnf4α levels. In conclusion, diet-induced hypercholesterolemia changes the expression and function of hepatic drug-metabolizing enzymes and transporters in rats, thereby possibly affecting drug metabolism and pharmacokinetics. In clinical hyperlipidemia, patients should strengthen drug monitoring to avoid possible drug exposure mediated risks.

Molecular targets of statins and their potential side effects: Not all the glitter is gold

Statins are a class of drugs widely used worldwide to manage hypercholesterolemia and the prevention of secondary heart attacks. Currently, available statins vary in terms of their pharmacokinetic and pharmacodynamic profiles. Although the primary target of statins is the inhibition of HMG-CoA reductase (HMGR), the rate-limiting enzyme in cholesterol biosynthesis, statins exhibit many pleiotropic effects downstream of the mevalonate pathway. These pleiotropic effects include the ability to reduce myocardial fibrosis, pathologic cardiac disease states, hypertension, promote bone differentiation, anti-inflammatory, and antitumor effects through multiple mechanisms. Although these pleiotropic effects of statins may be a cause for enthusiasm, there are many adverse effects that, for the most part, are unappreciated and need to be highlighted. These adverse effects include myopathy, new-onset type 2 diabetes, renal and hepatic dysfunction. Although these adverse effects may be relatively uncommon, considering the number of people worldwide who use statins daily, the actual number of people affected becomes quite large. Also, co-administration of statins with several other medications, herbal agents, and foods, which interact through common enzymatic pathways, can have untoward clinical consequences. In this review, we address these concerns.

An unusually impressive atorvastatin-induced elevation of serum alkaline phosphatase

A 90-year-old woman is referred six months after a transient ischaemic attack (TIA) with asymptomatic cholestatic liver function test (LFT) derangement. Following the TIA, atorvastatin and clopidogrel therapy are initiated. This is added to pre-existent once daily nifedipine for hypertension. Nifedipine (a weak inhibitor of CYP3A4 and competing substrate) and clopidogrel (a competitive inhibitor of CYP3A4) may have affected the metabolism of atorvastatin, resulting in the elevation of serum alkaline phosphatase levels to over six times the upper limit of normal. More often, statin therapy elevates serum alanine aminotransferase levels. Drug-induced liver injury (DILI) was deemed ‘probable’ as judged by the Roussel Uclaf Causality Assessment Method score. Statin therapy remains overwhelmingly safe, with benefits outweighing risks in the vast majority. The UK recommended LFT monitoring regime facilitates early recognition of DILI. Case reports are examined where similar drug combinations resulted in severe morbidity and mortality.

Optimizing treatment of renal cell carcinoma with VEGFR-TKIs: a comparison of clinical pharmacology and drug-drug interactions of anti-angiogenic drugs

Anti-angiogenic treatment is an important option that has changed the therapeutic landscape in various tumors, particularly in patients affected by renal cell carcinoma (RCC). Agents that block signaling pathways governing tumor angiogenesis have raised high expectations among clinicians. Vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) comprise a heterogeneous class of drugs with distinct pharmacological profiles, including potency, selectivity, pharmacokinetics and drug-drug interactions. Among them, tivozanib is one of the last TKIs introduced in the clinical practice; this drug selectively targets VEGFRs, it is characterized by a favorable pharmacokinetics and safety profile and has been approved as first-line treatment for patients with metastatic RCC (mRCC). In this article, we describe the clinical pharmacology of selected VEGFR-TKIs used for the treatment of mRCC, highlighting the relevant differences; moreover we aim to define the main pharmacologic characteristics of these drug.

Statins: a viable candidate for host-directed therapy against infectious diseases

Statins were first identified over 40 years ago as lipid-lowering drugs and have been remarkably effective in treating cardiovascular diseases. As research advanced, the protective effects of statins were additionally attributed to their anti-inflammatory, antioxidative, anti-thrombotic and immunomodulatory functions rather than lipid-lowering abilities alone. By promoting host defence mechanisms and inhibiting pathological inflammation, statins increase survival in human infectious diseases. At the cellular level, statins inhibit the intermediates of the host mevalonate pathway, thus compromising the immune evasion strategies of pathogens and their survival. Here, we discuss the potential use of statins as an inexpensive and practical alternative or adjunctive host-directed therapy for infectious diseases caused by intracellular pathogens, such as viruses, protozoa, fungi and bacteria.

Rhinacanthin-C Mediated Herb-Drug Interactions with Drug Transporters and Phase I Drug-Metabolizing Enzymes

Rhinacanthin-C is a major active constituent in Rhinacanthus nasutus (L.) Kurz, a plant widely used in herbal remedies. Its potential for pharmacokinetic herb-drug interaction may exist with drug transporters and drug metabolizing enzymes. This study assessed the possibility for rhinacanthin-C-mediated drug interaction by determining its inhibitory effects against major human efflux and influx drug transporters as well as various human cytochrome P450(CYP) isoforms. Rhinacanthin-C demonstrated a moderate permeability through the Caco-2 monolayers [P_{app (AP-to-BL)} = 1.26 × 10^-6 cm/s]. It significantly inhibited transport mediated by both P-glycoprotein (P-gp) (IC₅₀ = 5.20 µM) and breast cancer resistance protein (BCRP) (IC₅₀ = 0.83 µM) across Caco-2 and BCRP-overexpressing Madin-Darby canine kidney II cells (MDCKII) cells. This compound also strongly inhibited uptake mediated by organic anion-transporting polypeptide 1B1 (OATP1B1) (IC₅₀ = 0.70 µM) and OATP1B3 (IC₅₀ = 3.95 µM) in OATP1B-overexpressing HEK cells. In addition to its inhibitory effect on these drug transporters, rhinacanthin-C significantly inhibited multiple human CYP isoforms including CYP2C8 (IC₅₀ = 4.56 µM), 2C9 (IC₅₀ = 1.52 µM), 2C19 (IC₅₀ = 28.40 µM), and 3A4/5 (IC₅₀ = 53 µM for midazolam and IC₅₀ = 81.20 µM for testosterone), but not CYP1A2, 2A6, 2B6, 2D6, and 2E1. These results strongly support a high propensity for rhinacanthin-C as a perpetrator of clinical herb-drug interaction via inhibiting various influx and efflux drug transporters (i.e., P-gp, BCRP, OATP1B1, and OATP1B3) and CYP isoforms (i.e., CYP2C8, CYP2C9, and CYP2C19). Thus, the potential for significant pharmacokinetic herb-drug interaction should be addressed when herbal products containing rhinacanthin-C are to be used in conjunction with other prescription drugs.

Inhibitory effect of simvastatin in nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is one of the most common malignant head and neck cancers in southern China. Although the local and regional control of NPC has been considerably improved, patients with advanced disease still suffer from poor prognosis. Statins inhibit the mevalonate pathway and play antiproliferative and proapoptotic roles in a number of cancer cells. However, the effects and molecular mechanism of statins in NPC treatment remain unclear. In this study, the cell viability of NPC cell line, C666-1, after simvastatin exposure was determined using the alamarBlue Cell Viability Assay. Cell apoptosis in C666-1 treated with simvastatin was assessed by flow cytometry and TUNEL assay. The expression levels of cell cycle regulatory proteins were determined using western blotting. Simvastatin markedly decreased cell viability in a concentration-dependent manner, increased caspase 3 activity and induced apoptosis in C666-1 cells. Simvastatin induced Bim expression by regulating phosphorylation of transcriptional factor c-Jun. Simvastatin treatment induced cell cycle arrest in the G1 phase in C666-1 cells by inhibiting the expression of cyclin D1 and cyclin-dependent kinase 4, and enhancing p27 expression. Simvastatin treatment inhibited protein kinase B and extracellular signal regulated kinase 1/2 activation. In conclusion, the results of the present study reveal the possible molecular mechanism of simvastatin-induced anti-tumor effects in C666-1 and suggest that simvastatin is a potential chemotherapy agent in NPC treatment.

Application of nanotechnology to improve the therapeutic benefits of statins

Hyperlipidemia is defined as an elevated level of lipids and lipoproteins in the blood and is considered to be a significant risk factor for accelerating the process of atherosclerosis and, consequently, cardiovascular disease. The level of cholesterol, especially low-density lipoprotein cholesterol (LDL-C), is commonly elevated in hyperlipidemia and represents the primary therapeutic target. Statins are a group of drugs that function by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and are extremely efficacious in reducing elevated LDL-C in the serum and preventing atherosclerotic cardiovascular disease. However, statins have some limitations, such as poor aqueous solubility, low oral absorption, and, consequently, limited bioavailability when administered by the oral route. The field of nanotechnology is now well developed and some of these newer nanotechnology strategies offer systems with enhanced aqueous solubility of the statin, increased absorption, bioavailability, and controlled release of the statin at the site of administration. Here, we discuss nano-sized drug delivery systems to enhance the therapeutic potential of statins.

A Brief Drug Class Review: Considerations for Statin Use, Toxicity, and Drug Interactions

For approximately 30 years, statins have been effectively used to control cholesterol, thereby reducing the morbidity and mortality associated with cardiovascular disease. Evidence-based recommendations regarding how these drugs are dosed and used have changed significantly through the years. There are seven statins approved for use in the United States, and although the mechanism of action pertaining to cholesterol reduction is the same for all statins, each has its own specific pharmacologic profile. One unique aspect of statin dosing is understanding the potential drug interactions associated with statin use; interactions can occur with all statins, but the mechanism and type of interaction can vary significantly among drugs. These interactions can result in significant elevations in statin blood concentrations, thereby increasing the risk of the adverse effects of statins, the most significant of which is muscle toxicity. Practitioners who care for patients receiving statins should understand the pharmacologic differences among these drugs, as well as the varied drug interaction potential that all statins possess.

In vitro antibacterial effects of statins against bacterial pathogens causing skin infections

With financial considerations impeding research and development of new antibiotics, drug repurposing (finding new indications for old drugs) emerges as a feasible alternative. Statins are extensively prescribed around the world to lower cholesterol, but they also possess inherent antimicrobial properties. This study identifies statins with the greatest potential to be repurposed as topical antibiotics and postulates a mechanism of action for statins' antibacterial activity. Using broth microdilution, the direct antibacterial effects of all seven parent statins currently registered for human use and three selected statin metabolites were tested against bacterial skin pathogens Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Serratia marcescens. Simvastatin and pitavastatin lactone exerted the greatest antibacterial effects (minimum inhibitory concentrations of 64 and 128 μg/mL, respectively) against S. aureus. None of the statins tested were effective against E. coli, P. aeruginosa, or S. marcescens, but simvastatin hydroxy acid acid might be active against S. aureus, E. coli, and S. marcescens at drug concentrations > 256 μg/mL. It was found that S. aureus may exhibit a paradoxical growth effect when exposed to simvastatin; thus, treatment failure at high drug concentrations is theoretically probable. Through structure-activity relationship analysis, we postulate that statins' antibacterial action may involve disrupting the teichoic acid structures or decreasing the number of alanine residues present on Gram-positive bacterial cell surfaces, which could reduce biofilm formation, diminish bacterial adhesion to environmental surfaces, or impede S. aureus cell division.

Human Immunodeficiency Virus Infection, Antiretroviral Therapy, and Statin: a Clinical Update

PURPOSE OF REVIEW

This clinical update is intended to focus in relationship between HIV infection and use of antiretroviral therapy (ART) and statin.

RECENT FINDINGS

Though ART significantly changed the course of HIV infection, it is related to numerous side effects principally to the lipid profile. In this way, statins became one of the most used lipid-lowering therapies in this population. In our clinical update, we evaluated studies that demonstrate the relationship and molecular mechanisms that HIV infection and ART use trigger dyslipidemia and also the use of statin to reduce this condition. We have demonstrated that use of statin can be used in dyslipidemic HIV-infected people as long as there is no drug interaction with ART. Recently, studies using rosuvastatin have shown greater effects when compared to the other statins.

Current and Emerging Uses of Statins in Clinical Therapeutics: A Review

Statins, a class of cholesterol-lowering medications that inhibit 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, are commonly administered to treat atherosclerotic cardiovascular disease. Statin use may expand considerably given its potential for treating an array of cholesterol-independent diseases. However, the lack of conclusive evidence supporting these emerging therapeutic uses of statins brings to the fore a number of unanswered questions including uncertainties regarding patient-to-patient variability in response to statins, the most appropriate statin to be used for the desired effect, and the efficacy of statins in treating cholesterol-independent diseases. In this review, the adverse effects, costs, and drug–drug and drug–food interactions associated with statin use are presented. Furthermore, we discuss the pleiotropic effects associated with statins with regard to the onset and progression of autoimmune and inflammatory diseases, cancer, neurodegenerative disorders, strokes, bacterial infections, and human immunodeficiency virus. Understanding these issues will improve the prognosis of patients who are administered statins and potentially expand our ability to treat a wide variety of diseases.

The effect of atorvastatin treatment on serum oxysterol concentrations and cytochrome P450 3A4 activity

AIMS

Atorvastatin is known to both inhibit and induce the cytochrome P450 3A4 (CYP3A4) enzyme in vitro. Some clinical studies indicate that atorvastatin inhibits CYP3A4 but there are no well-controlled longer term studies that could evaluate the inducing effect of atorvastatin. We aimed to determine if atorvastatin induces or inhibits CYP3A4 activity as measured by the 4β-hydroxycholesterol to cholesterol ratio (4βHC : C).

METHODS

In this randomized, double-blind, placebo-controlled 6 month study we evaluated the effects of atorvastatin 20 mg day(-1) (n = 15) and placebo (n = 14) on oxysterol concentrations and determined if atorvastatin induces or inhibits CYP3A4 activity as assessed by the 4βHC : C index. The respective 25-hydroxycholesterol and 5α,6α-epoxycholesterol ratios were used as negative controls.

RESULTS

Treatment with atorvastatin decreased 4βHC and 5α,6α-epoxycholesterol concentrations by 40% and 23%, respectively. The mean 4βHC : C ratio decreased by 13% (0.214 ± 0.04 to 0.182 ± 0.04, P = 0.024, 95% confidence interval (CI) of the difference -0.0595, -0.00483) in the atorvastatin group while no significant change occurred in the placebo group. The difference in change of 4βHC : C between study arms was statistically significant (atorvastatin -0.032, placebo 0.0055, P = 0.020, 95% CI of the difference -0.069, -0.0067). The ratios of 25-hydroxycholesterol and 5α,6α-epoxycholesterol to cholesterol did not change.

CONCLUSIONS

The results establish atorvastatin as an inhibitor of CYP3A4 activity. Furthermore, 4βHC : C is a useful index of CYP3A4 activity, including the conditions with altered cholesterol concentrations.

The association between donor and recipient statin use and infections after allogeneic hematopoietic cell transplantation

Recent studies have reported that statin use may be associated with improved outcomes in patients with sepsis or respiratory viral infections. In the setting of allogeneic hematopoietic cell transplantation (HCT), it has been shown that donor and recipient statin use is associated with reduced risks of GVHD. We assessed in retrospective analysis whether donor or recipient statin use impacts infection risk after allogeneic HCT (n=1191). Although recipient statin use was associated with the increased incidence of Gram-negative bacteremia (adjusted hazard ratio (aHR) 2.22, (95% confidence interval (CI) 1.2-4.2), P=0.01) without affecting mortality, donor statin use was associated with an increased incidence of respiratory viral infections in recipients (aHR 2.84 (95% CI 1.3-6.0), P=0.007). The overall incidence of invasive fungal infections and CMV reactivation and CMV disease were not impacted by recipient or donor statin use. In conclusion, this study suggests that recipient or donor statin use may be associated with an increased incidence of some infections without adversely affecting mortality.

More ethical and more efficient clinical research: multiplex trial design

Background

Today’s clinical research faces challenges such as a lack of clinical equipoise between treatment arms, reluctance in randomizing for multiple treatments simultaneously, inability to address interactions and increasingly restricted resources. Furthermore, many trials are biased by extensive exclusion criteria, relatively small sample size and less appropriate outcome measures.

Findings

We propose a ‘Multiplex’ trial design that preserves clinical equipoise with a continuous and factorial trial design that will also result in more efficient use of resources. This multiplex design accommodates subtrials with appropriate choice of treatment arms within each subtrial. Clinical equipoise should increase consent rates while the factorial design is the best way to identify interactions.

Conclusion

The multiplex design may evolve naturally from today’s research limitations and challenges, while principal objections seem absent. However this new design poses important infrastructural, organisational and psychological challenges that need in depth consideration.

Are statins a viable option for the treatment of infections with the hepatitis C virus?

Statins are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors that are widely used for the treatment of hypercholesterolemia. Besides their cholesterol-lowering effect, statins have been reported to have antiviral activity against a variety of viruses, including hepatitis C virus (HCV). Several statins inhibit the in vitro replication of subgenomic HCV replicons and also suppress in vitro RNA replication of infectious HCV. The precise mechanism of the anti-HCV activity of statins has not yet been defined. Recent studies suggest that the antiviral effect may result from the inhibition of geranylgeranylation of cellular proteins, rather than the inhibition of cholesterol synthesis. Despite the antiviral effect observed in vitro, statin monotherapy seems to be insufficient for the treatment of chronic HCV infection. However, several prospective and retrospective studies have demonstrated that the addition of statins to IFN-α and ribavirin therapy increases SVR, RVR, and EVR rates without the occurrence of additional adverse events. These clinical data, together with the excellent safety profile and low cost, suggest that statins may play a role in HCV therapy until more potent and safe direct-acting antivirals become available. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication."