Acetoacetate enhances oxidative metabolism and response to toxicants of cultured kidney cells.

Cultured kidney cells maintained in conventional growth media with high glucose levels exhibit increased glycolytic activity compared to the cells in vivo. In contrast, renal proximal tubules utilize substrates such as ketone bodies and rely on mitochondrial oxidative phosphorylation. LLC-PK1 cells maintain many features of the proximal tubule but are exposed to glucose concentrations ranging from 17 to 25 mM. This may impact their reliability in predicting mitochondrial toxicity. This study is designed to test the impact of the ketone body acetoacetate on metabolic characteristics of LLC-PK1 cells. Basal respiration, maximal respiration, spare respiratory capacity and ATP-linked respiration were significantly increased in cells grown in growth medium supplemented with 5 mM acetoacetate. In contrast, glycolytic capacity, as well as glycolytic reserve were significantly reduced in the acetoacetate group. There was an increased expression in biomarkers of mitochondrial biogenesis, and an increase in mitochondrial protein expression. Cells grown in medium complemented with acetoacetate displayed a significantly lower LC50 when treated with clotrimazole and diclofenac. There was a marked increase in uncoupled respiration in the presence of diclofenac, while clotrimazole and ciprofibrate significantly decreased respiration in the acetoacetate. The results indicate that acetoacetate complemented media can alter cellular metabolism and increase sensitization to toxicants.

Toxic Myopathies.

PURPOSE OF REVIEW: This article reviews the pathogenesis, clinical features, and management of toxic myopathy related to common medications, critical illness, and illicit substances. RECENT FINDINGS: Muscle symptoms are common among statin users and are usually reversible after discontinuation of the statin; rarely, however, statins trigger an immune-mediated necrotizing myopathy that persists and requires immunomodulatory therapy. Autoantibodies targeting 3-hydroxy-3-methylglutaryl coenzyme A reductase can distinguish the toxic and immune-mediated forms. Immune checkpoint inhibitors, increasingly used in the treatment of advanced cancer, have recently been associated with the development of inflammatory myositis. A reversible mitochondrial myopathy has long been associated with zidovudine, but recent reports elucidate the risk of myopathy with newer antivirals, such as telbivudine and raltegravir. SUMMARY: The medications most commonly associated with myopathy include statins, amiodarone, chloroquine, hydroxychloroquine, colchicine, certain antivirals, and corticosteroids, and myopathy can occur with chronic alcoholism. Certain clinical, electrodiagnostic, and histologic features can aid in early recognition. Stopping the use of the offending agent reverses symptoms in most cases, but specific and timely treatment may be required in cases related to agents that trigger immune-mediated muscle injury.

Establishment and characterization of a mouse model of rhabdomyolysis by coadministration of statin and fibrate.

Rhabdomyolysis is characterized by elevation of plasma creatine phosphokinase (CPK) level, and multiple organ disorders, especially renal failure, as well as approximately 50% of acquired rhabdomyolysis are caused by pharmaceuticals. Statins are known to cause rhabdomyolysis, and its incidence is ≥10 times higher with coadministration of statin and fibrate. The purpose of this study is to establish a mouse model of drug-induced rhabdomyolysis by coadministration of statin and fibrate to clarify the mechanisms of its myotoxicity. We administered lovastatin (LV) and gemfibrozil (GF) with a glutathione synthesis inhibitor, L-buthionine-(S,R)-sulfoximine (BSO), to C57BL/6 J female mice once daily for 3 days. The plasma levels of CPK and aspartate aminotransferase (AST) were prominently increased, and the increase in plasma miR-206-3p and miR-133-3p levels, not the increase of miR-122-5p and miR-208-3p levels, suggested skeletal muscle-specific toxicity. The caspase 3/7 activity and mRNA levels of oxidative stress-related factors were elevated in skeletal muscle. Pharmacokinetic parameters showed that blood levels of statin were significantly increased by coadministered GF. The possibility of kidney injury was examined as in clinical rhabdomyolysis. In histological examination, vacuoles were observed in renal proximal tubules, and the plasma renal injury marker, lipocalin 2/neutrophil gelatinase-associated lipocalin (Lcn2/Ngal), was markedly increased in the mice coadministered LV and GF, suggesting mild complications of acute kidney injury. A quantitative comparison of the myotoxic potential of various statins was successfully performed using the present method. In this study, a rhabdomyolysis mouse model was established by coadministration of the clinically using statin and fibrate. This mouse model may be useful to identify drugs that have high risk for rhabdomyolysis.

Increased toxicity when fibrates and statins are administered in combination--a metabolomics approach with rats.

Combination therapies with fibrates and statins are used to treat cardiovascular diseases, because of their synergistic effect on lowering plasma lipids. However, fatal side-effects like rhabdomyolysis followed by acute renal necrosis sometimes occur. To elucidate biochemical changes resulting from the interaction of fibrates and statins, doses of 100 mg/kg fenofibrate, 50mg/kg clofibrate, 70 mg/kg atorvastatin and 200 mg/kg pravastatin as well as combinations thereof were administered to Crl:Wi(Han) rats for 4 weeks. Plasma metabolome profile was measured on study days 7, 14 and 28. Upon study termination, clinical pathology parameters were measured. In a separate experiment plasmakinetic data were measured in male rats after 1 week of drug administration in monotherapy as well as in combinations. Lowering of blood lipid levels as well as toxicological effects, like liver cell degradation (statins) and anemia (fibrates) and distinct blood metabolite level alterations were observed in monotherapy. When fibrates and statins were co-administered metabolite profile interactions were generally underadditive or at the utmost additive according to the linear mixed effect model. However, more metabolite levels were significantly altered during combination therapy. New effects on the antioxidant status and the cardiovascular system were found which may be related to a development of rhabdomyolysis. Accumulation of drugs during the combination therapy was not observed.

Fragrance material review on 2-phenoxyethyl propionate.

A toxicologic and dermatologic review of 2-phenoxyethyl propionate when used as a fragrance ingredient is presented. 2-Phenoxyethyl propionate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 2-phenoxyethyl propionate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, skin sensitization, and genotoxicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances.

Can pharmaceuticals interfere with the synthesis of active androgens in male fish? An in vitro study.

The in vitro interference of fibrate (gemfibrozil, clofibrate, clofibric acid), anti-inflammatory (ibuprofen, diclofenac), and anti-depressive (fluoxetine, fluvoxamine) drugs with key enzymatic activities-C17,20-lyase and CYP11ß-involved in the synthesis of active androgens in gonads of male carp have been investigated. Among the tested compounds, fluvoxamine and fluoxetine were the strongest inhibitors of C17,20-lyase and CYP11ß enzymes, with IC50s in the range of 321-335 µM and 244-550 µM, respectively. To our knowledge this is the first report on the interaction of pharmaceutical compounds with enzymatic systems involved in the synthesis of oxy-androgens. As oxy-androgens are known to influence spermatogenesis and stimulate reproductive behavior and secondary sexual characteristics in male fish, this work highlights the need for further investigating these endpoints when designing specific in vivo studies to assess the endocrine disruptive effect of pharmaceuticals in fish.