Evaluation of the synergistic adverse effects of concomitant therapy with statins and fibrates on rhabdomyolysis

Development of Novel siRNA Therapeutics: A Review with a Focus on Inclisiran for the Treatment of Hypercholesterolemia

Over the past two decades, it was discovered that introducing synthetic small interfering RNAs (siRNAs) into the cytoplasm facilitates effective gene-targeted silencing. This compromises gene expression and regulation by repressing transcription or stimulating sequence-specific RNA degradation. Substantial investments in developing RNA therapeutics for disease prevention and treatment have been made. We discuss the application to proprotein convertase subtilisin/kexin type 9 (PCSK9), which binds to and degrades the low-density lipoprotein cholesterol (LDL-C) receptor, interrupting the process of LDL-C uptake into hepatocytes. PCSK9 loss-of-function modifications show significant clinical importance by causing dominant hypocholesterolemia and lessening the risk of cardiovascular disease (CVD). Monoclonal antibodies and small interfering RNA (siRNA) drugs targeting PCSK9 are a significant new option for managing lipid disorders and improving CVD outcomes. In general, monoclonal antibodies are restricted to binding with cell surface receptors or circulating proteins. Similarly, overcoming the intracellular and extracellular defenses that prevent exogenous RNA from entering cells must be achieved for the clinical application of siRNAs. N-acetylgalactosamine (GalNAc) conjugates are a simple solution to the siRNA delivery problem that is especially suitable for treating a broad spectrum of diseases involving liver-expressed genes. Inclisiran is a GalNAc-conjugated siRNA molecule that inhibits the translation of PCSK9. The administration is only required every 3 to 6 months, which is a significant improvement over monoclonal antibodies for PCSK9. This review provides an overview of siRNA therapeutics with a focus on detailed profiles of inclisiran, mainly its delivery strategies. We discuss the mechanisms of action, its status in clinical trials, and its prospects.

Efficacy, safety and tolerability of combined low-dose simvastatin-fenofibrate treatment in primary mixed hyperlipidaemia

OBJECTIVE

In order to assess the long-term (12 months) efficacy and safety of fenofibrate administered with simvastatin in the treatment of primary mixed hyperlipidaemia, we conducted a study that compared increasing dosages of these drugs in subgroups of men and women belonging to a clinical sample of out-patients.

DESIGN

This was an open study carried out in patients with primary mixed hyperlipidaemia (lipoprotein phenotype IIb) who needed a combined therapeutic approach because of their poor response to a single-drug regimen with an HMG-CoA reductase inhibitor (simvastatin). Thus, a fibrate (fenofibrate) was added to the therapy. The study lasted 12 months.

PATIENTS

Forty-five patients (mean age: 58.9 +/- 11.3 years) with primary mixed hyperlipidaemia who showed a poor response to the single-drug hypolipidaemic treatment were enrolled. Their average plasma triglyceride level was consistently above 300 mg/dL and low-density lipoprotein cholesterol (LDL-C) was over 160 mg/dL after at least 6 months of a single hypolipidaemic drug (simvastatin) regimen plus antiatherogenic dietary treatment.

INTERVENTIONS

Five patients received simvastatin 10mg once daily in addition to fenofibrate 200mg; 26 patients received simvastatin 20mg once daily plus fenofibrate 200mg; 11 patients received simvastatin 20mg once daily plus fenofibrate 300mg; and three patients received simvastatin 30mg once daily plus fenofibrate 200mg. The patients were allocated to treatment groups on the basis of their relative response to the therapy. Those making up the progressively higher agent/dose groups were the individuals at higher cardiovascular risk according to the total cholesterol and non-high-density lipoprotein cholesterol (HDL-C) values.

RESULTS

The double-drug regimen given for 12 months to four different groups, according to the different combined dosages of simvastatin and fenofibrate, resulted in a reduction in total cholesterol of 18% (p </= 0.05) to 39% (p </= 0.05), in LDL-C of 21% (not significant) to 39% (p </= 0.05) and in triglycerides of 35% (p </= 0.05) to 56% (p </= 0.01), and an increase in HDL-C of 8% (p </= 0.05) to 30% (not significant). The cardiovascular risk ratio (total cholesterol/HDL-C) at the end of the study was reduced by 33-60%, whereas the non-HDL-C decreased by 25-38%. No serious adverse effects were reported by the patients. Neither liver biochemistry nor creatine kinase serum concentration were significantly changed. Discontinuation of treatment, if necessary, in case of the occurrence of clinically subjective or objective evidence of adverse effects was assured.

CONCLUSION

The results confirmed the efficacy of the combination of fenofibrate and simvastatin. The combined therapeutic approach was shown to be safe for the treatment of primary mixed hyperlipidaemia, at least in patients with normal hepatic and renal function.

Statin-induced apoptosis linked with membrane farnesylated Ras small G protein depletion, rather than geranylated Rho protein

Rhabdomyolysis is a severe adverse effect of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins). This myopathy is strongly enhanced by the combination with statins and fibrates, another hypolipidaemic agent. We have evaluated the initial step of statin-induced apoptosis by the detection of membrane flip-flop using flow cytometric analysis. L6 rat myoblasts were treated with various statins (atorvastatin (3 μm), cerivastatin (3 μm), fluvastatin (3 μm), pravastatin (3 mm), or simvastatin (3 μm)) for 2, 4 or 6 h followed by reacting with FITC-conjugated annexin V for the detection of initial apoptosis signal (flip-flop). Various statin-treated myoblasts were significantly stained with FITC-annexin V at 6 h, whereas they were not detected at 2 h. Moreover, immunoblot analysis indicated that when the cells were treated with cerivastatin (3 μm), membrane-associated Ras protein was activated and detached until 6 h, resulting in cell death through the consequent activation of caspase-8. On the other hand, since cytosolic Ras activation did not activate, there is still an unknown mechanism in statin-related Ras depletion. In conclusion, statin-induced apoptosis in muscular tissue was directly initiated by the farnesyl-anchored Ras protein depletion from cell membrane with subsequent apoptosis.

Synergistic action of statins and nitrogen-containing bisphosphonates in the development of rhabdomyolysis in L6 rat skeletal myoblasts

Objectives

Nitrogen-containing bisphosphonates, which are widely used to treat osteoporosis, act as inhibitors of farnesyl pyrophosphate synthase, one of the key enzymes of the mevalonate pathway, and thus may have the potential to enhance the effect of statins (inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase). In this study, we evaluated the synergistic effect of two nitrogen-containing bisphosphonates, alendronate and risedronate, in statin-induced apoptosis in rat skeletal L6 myoblasts.

Methods

L6 rat myoblasts were differentiated with drugs. DNA fragmentation was measured and small GTPase was detected by immunoblotting.

Key findings

Alendronate and risedronate caused dose-dependent apoptosis of L6 myoblasts. Risedronate induced detachment of rho GTPase from the cell membrane, followed by activation of the caspase-8-related cascade. Risedronate-induced apoptosis was synergistically enhanced with atorvastatin and significantly reduced by addition of geranylgeraniol. By contrast, alendronate did not reduce membrane GTPases and the apoptosis was caspase independent.

Conclusions

These results suggest that risedronate-induced apoptosis is related to geranylgeranyl pyrophosphate depletion followed by rho detachment, whereas alendronate affects are independent of rho. Our results suggest a risk of synergistic action between nitrogen-containing bisphosphonates and statins in the development of rhabdomyolysis when treating osteoporosis in women with hyperlipidaemia.

Negative evidence for stachydrine or Galeopsis ladanum L. seeds as the causal agents of coturnism after quail meat ingestion

Quail poisoning is known to produce an acute myoglobinuric syndrome called coturnism. The cause of this syndrome is still unknown, although it has been postulated that Galeopsis ladanum L. seeds, in particular lipidic compounds or stachydrine, are responsible for this toxicity. Thus, we aimed to study the implication of this plant in coturnism in order to explore the physiopathology of the disease, especially with regard to stachydrine and lipidic compounds extracted from seeds. For this purpose, Wistar rats were fed with G. ladanum seed extracts or with quail meat. However, the rhabdomyolysis outbreak could not be reproduced in any case. Therefore, in view of our results and experimental conditions, seeds of G. ladanum and stachydrine do not appear to be the responsible agents of the myopathic outbreak. This conclusion is supported by the following facts: direct administration of extracts of seeds of G. ladanum or stachydrine produces no myotoxicity in rats; G. ladanum seeds are not toxic to quails and meat from quails fed G. ladanum seeds is not toxic to rats.

Bezafibrate induces myotoxicity in human rhabdomyosarcoma cells via peroxisome proliferator-activated receptor alpha signaling

Fibrates, the ligands of peroxisome proliferator-activated receptor alpha (PPARalpha), are used as a class of lipid-lowering drugs in clinical practice for the treatment of dyslipidemia. Fibrates are well tolerated in most cases concomitantly with occasional adverse reactions including muscular toxicity, which is enhanced by the combination with statins. This study was designed to investigate the effects of bezafibrate as a PPARalpha agonist on human embryo rhabdomyosarcoma (RD) cells and possible mechanisms responsible for bezafibrate-mediated myopathy. The results revealed that bezafibrate caused a dose-dependent decrease in cell viability, which was fortified in association with atorvastatin at a pharmacological dose. Bezafibrate at toxic doses of 300 and 1000microM upregulated PPARalpha at the mRNA level, counteracted by a PPARalpha antagonist (MK886). Bezafibrate at a toxic dose induced typical apoptotic characteristics related to the inhibition of phosphorylation of Akt which was blocked by PPARalpha antagonist. Toxic doses of bezafibrate initiated a significant increase in pyruvate dehydrogenase kinase 4 mRNA and protein levels, compromised by MK886. These results suggest the critical roles of PPARalpha signaling in bezafibrate-induced myotoxicity and the involvement of apoptosis through Akt pathway.

Drug-screening platform based on the contractility of tissue-engineered muscle

A tissue-based approach to in vitro drug screening allows for determination of the cumulative positive and negative effects of a drug at the tissue rather than the cellular or subcellular level. Skeletal muscle myoblasts were tissue-engineered into three-dimensional muscle with parallel myofibers generating directed forces. When grown attached to two flexible micro-posts (mu posts) acting as artificial tendons in a 96-well plate format, the miniature bioartificial muscles (mBAMs) generated tetanic (active) forces upon electrical stimulation measured with a novel image-based motion detection system. mBAM myofiber hypertrophy and active force increased in response to insulin-like growth factor 1. In contrast, mBAM deterioration and weakness was observed with a cholesterol-lowering statin. The results described in this study demonstrate the integration of tissue engineering and biomechanical testing into a single platform for the screening of compounds affecting muscle strength.

FLOW CYTOMETRIC EVALUATION OF SYNERGISTIC PRO-APOPTOTIC EFFECTS OF STATINS AND CLOFIBRATES IN IM-9 HUMAN LYMPHOBLASTS

1. In the present study, we evaluated fibrate-mediated potentiation of statin-induced apoptosis in IM-9 human lymphoblasts. 2. The pro-apoptotic effects of statin and fibrate were measured by flow cytometry with biotin-annexin V, followed by addition of avidin-fluorescein isothiocyanate and propidium iodide. Apoptosis was confirmed using karyopyknotic staining, as well as detection of DNA fragmentation and caspase 3 activation. 3. Incubation of IM-9 cells with both 0.1 micromol/L cerivastatin and 200 micromol/L clofibrate had a synergistic effect compared with 0.1 micromol/L cerivastatin alone or 200 micromol/L clofibrate alone. The magnitude of apoptosis induced by various combinations of statins and clofibrate were as follows: cerivastatin (0.1 micromol/L) + clofibrate (200 micromol/L) > atorvastatin (0.1 micromol/L) + clofibrate (200 micromol/L) > pravastatin (100 micromol/L) + clofibrate (200 micromol/L). Other fibrates (bezafibrate and clinofibrate) did not show any synergistic effect. Furthermore, karyopyknotic staining, caspase 3 activation and DNA fragmentation demonstrated synergistic pro-apoptotic effects of statin and fibrate. 4. The results of the present study suggest that simultaneous treatment with statins and clofibrate could provide improved therapeutic efficacy in leukaemia patients.

Iatrogenic rheumatic syndromes in the elderly

Rheumatic complaints are common in the geriatric population. However, uncommonly autoimmune or musculoskeletal complaints and disorders may arise as a consequence of pharmacotherapy. These rare events include stain myopathy, drug-induced lupus, arthralgias, vasculitis, or tight skin syndromes. This article discusses the possible iatrogenic causes of rheumatic conditions, potential inciting agents, and the various types of rheumatic manifestations seen in the elderly.

Inhibitory effects of statins on human monocarboxylate transporter 4

Human MCT4 (SLC16A3) is responsible for the efflux of L-lactic acid from skeletal muscle cells and is essential for muscle homeostasis. However, the effects of monocarboxylate drugs, such as statins on the MCT4-mediated transport of L-lactic acid have not been elucidated. Inhibition of L-lactic acid transport mediated by MCT4 might to lead to collapse of muscle homeostasis. The aim of this study was to establish an MCT4 transfected cell line and to clarify the transport mechanism of L-lactic acid and the effects of statins on this transport system. Results of Western blot analyses and immunohistochemistry studies indicated that the expression of CD147 and MCT4-FLAG protein were observed and was displayed clear plasma membrane localization in CD147 and MCT4-FLAG co-transfected cell line (cm cells). Uptake of L-lactic acid in cm cells was significantly greater than that in cells transfected with a vector alone. L-lactic acid uptake was concentration-dependent with a K(m) value of 28.43+/-3.87 mM. The results of a previous study showing a K(m) value of 28.5 mM in hMCT4-expressed oocytes. Lipophilic statins significantly inhibited [(14)C] L-lactic acid uptake in a concentration-dependent manner. In contrast, the inhibitory effects of hydrophilic statins were very weak.

Clofibrate-induced apoptosis is mediated by Ca2+-dependent caspase-12 activation

The mechanism of fibrate-induced myopathy was investigated in this report. When clofibrate (30 to 300 microM) was applied to L6 rat skeletal myoblasts, dose-dependently apoptosis was observed within 24 h. In the apoptotic myoblasts, a caspase-12 cleavage was observed at 2 h and with following caspases-9 and -3-related cascade activation. In contrast, the neutral protease calpain, that is a key enzyme in ER stress-related apoptosis via caspase-12 activation, was significantly decreased during apoptosis. Next, the authors evaluated a role of calcium-dependent signal(s). When clofibrate was added into medium, cytosolic calcium concentration was rapidly and persistently increased. On the other hand, an addition of 10 mM EGTA depressed sustained calcium phase, and concurrent myoblasts apoptosis was completely inhibited. Taken together, our findings indicate that the clofibrate-induced myopathy is triggered by Ca2+ influx, then activated cytosolic caspase-12 through calpain-independent cascade, and consequently caused apoptotic DNA fragmentation.

Statins and PPARalpha agonists induce myotoxicity in differentiated rat skeletal muscle cultures but do not exhibit synergy with co-treatment

Statins and fibrates (weak PPARalpha agonists) are prescribed for the treatment of lipid disorders. Both drugs cause myopathy, but with a low incidence, 0.1-0.5%. However, combined statin and fibrate therapy can enhance myopathy risk. We tested the myotoxic potential of PPAR subtype selective agonists alone and in combination with statins in a differentiated rat myotube model. A pharmacologically potent experimental PPARalpha agonist, Compound A, induced myotoxicity as assessed by TUNEL staining at a minimum concentration of 1 nM, while other weaker PPARalpha compounds, for example, WY-14643, Gemfibrozil and Bezafibrate increased the percentage of TUNEL-positive nuclei at micromolar concentrations. In contrast, the PPARgamma agonist Rosiglitazone caused little or no cell death at up to 10 muM and the PPARdelta ligand GW-501516 exhibited comparatively less myotoxicity than that seen with Compound A. An experimental statin (Compound B) and Atorvastatin also increased the percentage of TUNEL-positive nuclei and co-treatment with WY-14643, Gemfibrozil or Bezafibrate had less than a full additive effect on statin-induced cell killing. The mechanism of PPARalpha agonist-induced cell death was different from that of statins. Unlike statins, Compound A and WY-14643 did not activate caspase 3/7. In addition, mevalonate and geranylgeraniol reversed the toxicity caused by statins, but did not prevent the cell killing induced by WY-14643. Furthermore, unlike statins, Compound A did not inhibit the isoprenylation of rab4 or rap1a. Interestingly, Compound A and Compound B had differential effects on ATP levels. Taken together, these observations support the hypothesis that in rat myotube cultures, PPARalpha agonism mediates in part the toxicity response to PPARalpha compounds. Furthermore, PPARalpha agonists and statins cause myotoxicity through distinct and independent pathways.

Evaluation of apoptosis and necrosis induced by statins using fluorescence-enhanced flow cytometry

The purpose of this study was to evaluate the apoptosis and necrosis induced by five kinds of statins in IM-9 human lymphoblasts with fluorescence-enhanced flow cytometry using avidin-biotin complex. IM-9 human lymphoblasts (2 x 10(4) cells/cm2) were seeded into tissue culture plates and incubated with five kinds of statins. Statin-treated cells were first incubated with biotin-annexin V, followed by addition of avidin-FITC and propidium iodide, and then subjected to flow cytometry. The fluorescence intensity was enhanced using an avidin-biotin complex system, resulting in successful separate determination of the statin-induced apoptosis and necrosis by flow cytometry, which enabled us to quantitatively evaluate the statin-induced cell damage. Flow cytometric analysis results in the intensity of statin-induced apoptosis in IM-9 cells as follows: atorvastatin cerivastatin>fluvastatin simvastatin>pravastatin. The intensity of statin-induced necrosis in IM-9 cells was expressed as follows: atorvastatin cerivastatin>fluvastatin simvastatin>pravastatin. The total damage of IM-9 cells induced by five kinds of statins were expressed as the sum of both percentages of apoptosis and necrosis as follows: atorvastatin cerivastatin>fluvastatin simvastatin>pravastatin. Our studies show that fluorescence enhancement with avidin-biotin complex is useful for the identification and quantitation of annexin-positive apoptosis cells and thus, the fluorescence-enhanced flow cytometry was shown to be applicable for screening of statins as new anti-leukemia agents.

Iatrogenic Rheumatic Syndromes in the Elderly

Rheumatic complaints are common in the geriatric population. However, uncommonly autoimmune or musculoskeletal complaints and disorders may arise as a consequence of pharmacotherapy. These rare events include statin myopathy, drug-induced lupus, arthralgias, vasculitis, or tight skin syndromes. This article will discuss the possible iatrogenic causes of rheumatic conditions, potential inciting agents, and the various types of rheumatic manifestations seen in the elderly.

Rhabdomyolysis from Simvastatin Triggered by Infection and Muscle Exertion

A 42-year-old woman received a 6-month course of simvastatin (20 mg/d) for hypercholesterolemia. Despite an infection with fever, fatigue, myalgias, and lumbar pain, she continued to perform her regular sports activities. Neurologic examination revealed bilateral ptosis and slight upper limb weakness. Serum creatine kinase was 41,000 U/L. Needle electromyography was nonspecifically abnormal. Discontinuation of simvastatin and reduction of the sports activities was followed by a prompt continual lowering of the elevated muscle enzymes to normal values over a 2-week period. The patient's infection, regular sports activity despite the infection, and a suspected mitochondrial defect were regarded as triggers of rhabdomyolysis.

Myopathien unter der Therapie mit Lipidsenkern

Myopathies ranging from myalgia to clinically asymptomatic creatine kinase (CK) elevation and to life-threatening rhabdomyolysis belong to the most important complications of lipid-lowering therapies with fibrates and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, i.e., statins. Rhabdomyolysis is a rare side effect of statin therapy with an estimated incidence of 0.2/1 million prescriptions. Myalgia and muscle cramps were reported by up to 5% of patients, but they were observed with the same percentage in controls receiving placebo. Due to increasing numbers of patients under lipid-lowering therapy, however, more and more patients present in neuromuscular units with the differential diagnosis of a fibrate- or statin-induced myopathy.

Gemfibrozil and its glucuronide inhibit the organic anion transporting polypeptide 2 (OATP2/OATP1B1:SLC21A6)-mediated hepatic uptake and CYP2C8-mediated metabolism of cerivastatin: analysis of the mechanism of the clinically relevant drug-drug interaction between cerivastatin and gemfibrozil

A serious pharmacokinetic interaction between cerivastatin (CER) and gemfibrozil (GEM) has been reported. In the present study, we examined the inhibitory effects of GEM and its metabolites, M3 and gemfibrozil 1-O-beta-glucuronide (GEM-1-O-glu), on the uptake of CER by human organic anion transporting polypeptide 2 (OATP2)-expressing cells and its metabolism in cytochrome P450 expression systems. Uptake studies showed that GEM and GEM-1-O-glu significantly inhibited the OATP2-mediated uptake of CER with IC(50) values of 72 and 24 microM, respectively. They also inhibited the CYP2C8-mediated metabolism of CER with IC(50) values of 28 and 4 microM, respectively, whereas M3 had no effects. GEM and GEM-1-O-glu minimally inhibited the CYP3A4-mediated metabolism of CER. The IC(50) values of GEM and GEM-1-O-glu for the uptake and the metabolism of CER obtained in the present study were lower than their total, and not unbound, plasma concentrations. However, considering the possibly concentrated high unbound concentrations of GEM-1-O-glu in the liver and its relatively larger plasma unbound fraction compared with GEM itself, the glucuronide inhibition of the CYP2C8-mediated metabolism of CER appears to be the main mechanism for the clinically relevant drug-drug interaction. Previously reported clinical drug interaction studies showing that coadministration of GEM with pravastatin or pitavastatin, both of which are known to be cleared from the plasma by the uptake transporters in the liver, only minimally (less than 2-fold) increased the area under the plasma concentration-time curve of these statins, also supported our present conclusion.

Comparing myotoxic effects of squalene synthase inhibitor, T-91485, and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors in human myocytes

TAK-475 is a squalene synthase inhibitor, rapidly metabolized to T-91485 in vivo. We investigated the myotoxicities of T-91485 and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors in a human rhabdomyosarcoma cell line, RD, and in human skeletal myocytes. In differentiated RD cells, T-91485, atorvastatin (ATV) and simvastatin acid (SIM) inhibited cholesterol biosynthesis, with IC(50) values of 36, 2.8 and 3.8 nM, respectively. ATV and SIM decreased the intracellular ATP content, with IC(25) values (concentrations giving a 25% decrease in intracellular ATP content) of 0.61 and 0.44 microM, respectively. Although T-91485 potently inhibited cholesterol synthesis in RD cells, the IC(25) value exceeded 100 microM. In human skeletal myocytes, T-91485, ATV and SIM concentration-dependently inhibited cholesterol biosynthesis, with IC(50) values of 45, 8.6 and 8.4 nM, respectively. ATV and SIM decreased intracellular ATP content, with IC(25) values of 2.1 and 0.72 microM, respectively. Although T-91485 potently inhibited cholesterol synthesis, the IC(25) value exceeded 100 microM. Myotoxicity induced by ATV was prevented by mevalonate or geranylgeranyl-PP, but not by squalene in skeletal cells. Furthermore, T-91485 attenuated the myotoxicity of ATV. These findings suggest that TAK-475 and T-91485 may not only be far from myotoxic, they may also decrease statin-induced myotoxicity in lipid-lowering therapy.