BACKGROUND: Many commonly used drugs were evaluated as repurposed treatment options since the emergence of the COVID-19 pandemic. The benefit of lipid-lowering agents has been controversial in this regard. In this systematic review, we assessed the effect of these medications as adjunctive therapy in COVID-19 by the inclusion of randomized controlled trials (RCTs).
METHODS: We searched four international databases including PubMed, the Web of Science, Scopus, and Embase for RCTs in April 2023. The primary outcome was mortality, while other efficacy indices were considered secondary outcomes. In order to estimate the pooled effect size of the outcomes, considering the odds ratio (OR) or standardized mean difference (SMD) and 95% confidence interval (CI), random-effect meta-analyses was conducted.
RESULTS: Ten studies involving 2,167 COVID-19 patients using statins, omega-3 fatty acids, fenofibrate, PCSK9 inhibitors, and nicotinamide as intervention compared to control or placebo, were included. No significant difference was found in terms of mortality (OR 0.96, 95% CI 0.58 to 1.59, p-value = 0.86, I2 = 20.4%) or length of hospital stay (SMD -0.10, 95% CI -0.78 to 0.59, p-value = 0.78, I2 = 92.4%) by adding a statin to the standard of care. The trend was similar for fenofibrate and nicotinamide. PCSK9 inhibition, however, led to decreased mortality and an overall better prognosis. Omega-3 supplementation showed contradicting results in two trials, suggesting the need for further evaluation.
CONCLUSIONS: Although some observational studies found improved outcomes in patients using lipid-lowering agents, our study found no benefit in adding statins, fenofibrate, or nicotinamide to COVID-19 treatment. On the other hand, PCSK9 inhibitors can be a good candidate for further assessment. Finally, there are major limitations in the use of omega-3 supplements in treating COVID-19 and more trials are warranted to evaluate this efficacy.

Thirty-to-forty percent of patients with primary biliary cholangitis inadequately respond to ursodeoxycholic acid. Our aim was to assemble national, real-world data on the effectiveness of obeticholic acid (OCA) as a second-line treatment, alongside non-licensed therapy with fibric acid derivatives (bezafibrate or fenofibrate).
This was a nationwide observational cohort study conducted from August 2017 until June 2021.
We accrued data from 457 patients; 349 treated with OCA and 108 with fibric acid derivatives. At baseline/pre-treatment, individuals in the OCA group manifest higher risk features compared with those taking fibric acid derivatives, evidenced by more elevated alkaline phosphatase values, and a larger proportion of individuals with cirrhosis, abnormal bilirubin, prior non-response to ursodeoxycholic acid, and elastography readings >9.6kPa (P < .05 for all). Overall, 259 patients (OCA) and 80 patients (fibric acid derivatives) completed 12 months of second-line therapy, yielding a dropout rate of 25.7% and 25.9%, respectively. At 12 months, the magnitude of alkaline phosphatase reduction was 29.5% and 56.7% in OCA and fibric acid groups (P < .001). Conversely, 55.9% and 36.4% of patients normalized serum alanine transaminase and bilirubin in the OCA group (P < .001). The proportion with normal alanine transaminase or bilirubin values in the fibric acid group was no different at 12 months compared with baseline. Twelve-month biochemical response rates were 70.6% with OCA and 80% under fibric acid treatment (P = .121). Response rates between treatment groups were no different on propensity-score matching or on sub-analysis of high-risk groups defined at baseline.
Across the population of patients with primary biliary cholangitis in the United Kingdom, rates of biochemical response and drug discontinuation appear similar under fibric acid and OCA treatment.

Gemfibrozil (GEM) is an orally administered lipid-regulating fibrate derivative drug sold under the brand name Lopid®, among others. Since its approval in the early 80s, GEM has been largely applied to treat hypertriglyceridemia and other disorders of lipid metabolism. Though generally well tolerated, GEM can alter the distribution and the free, active concentration of some co-administered drugs, leading to adverse effects. Most of them appear to be related to the ability of GEM to bind with high affinity human serum albumin (HSA), the major drug-carrier protein in blood plasma. Here, we report the crystal structure of HSA in complex with GEM. Two binding sites have been identified, namely Sudlow\'s binding sites I (FA7) and II (FA3-FA4). A comparison of the crystal structure of HSA in complex with GEM with those of other previously described HSA-drug complexes enabled us to appreciate the analogies and differences in their respective binding modes. The elucidation of the molecular interaction between GEM and HSA might offer the basis for the development of novel GEM derivatives that can be safely and synergistically co-administered with other drugs, enabling augmented therapeutic efficacies.

By analysis of the data from the Toxicogenomics Database (TG-GATEs), histidine decarboxylase gene (Hdc) was identified as largely and commonly upregulated by three fibrates, clofibrate, fenofibrate, and WY-14,643, which are known to induce hepatocellular hypertrophy and proliferation via stimulation of peroxisome proliferator-activated receptor α (PPARα) in rodents. As histamine has been reported to be involved in the proliferation of liver cells, the present study was conducted to focus on Hdc. Among other genes related to histidine and histamine, the expression of the gene of histamine ammonia lyase (Hal) was exclusively mobilized by the three fibrates. The expression of Hdc, which was usually very low in the liver, was increased with the repeated administration of fibrates, and concomitantly, the constitutive expression of Hal was suppressed. An interpretation is that the formation of urocanic acid from histidine under the normal condition switches to the formation of histamine. The mobilization of gene expression of Hdc and Hal by PPARα agonists could not be reproduced in primary cultured hepatocytes. The Hdc mRNA appeared to be translated to a protein which is processed differently from brain but similarly to gastric mucosa. Surprisingly, the fibrates caused hepatic hypertrophy but no induction of Hdc mRNA at all in mice. These results revealed that the changes in the histidine catabolism by PPARα agonists might be partially, but not directly, involved in the hepatocyte proliferation in rats, and there is a large genetic distance even between rat and mouse.

Although peroxisome proliferator-activated receptor α (PPARα) agonists are obviously hepatocarcinogenic in rodents, they have been widely used for dyslipidemia and proven to be safe for clinical use without respect to the species difference. It is established that PPARα acts as a part of the transcription factor complex, but its precise mechanism is still unknown. Using the data of Toxicogenomics Database, reliable genes responsive to PPARα agonists, clofibrate, fenofibrate and WY-14,643, in rat liver, were extracted from both in vivo and in vitro data, and sorted by their fold increase. It was found that there were many genes responding to fibrates exclusively in vivo. Most of the in vivo specific genes appear to be unrelated to lipid metabolism and are not upregulated in the kidney. Fifty-seven genes directly related to cell proliferation were extracted from in vivo data, but they were not induced in vitro at all. Analysis of PPAR-responsive elements could not explain the observed difference in induction. To evaluate possible interaction between neighboring genes in gene expression, the correlation of the fold changes of neighboring genes for 22 drugs with various PPARα agonistic potencies were calculated for the genes showing more than 2.5 fold induction by 3 fibrates in vivo, and their genomic location was compared with that of the human orthologue. In the present study, many candidates of genes other than lipid metabolism were selected, and these could be good starting points to elucidate the mechanism of PPARα agonist-induced rodent-specific toxicity.

Primary Biliary Cholangitis is a progressive, autoimmune cholestatic liver disorder. Cholestasis with disease progression may lead to dyslipidemia, osteodystrophy and fat-soluble vitamin deficiency. Portal hypertension may develop prior to advanced stages of fibrosis. Untreated disease may lead to cirrhosis, hepatocellular cancer and need for orthotopic liver transplantation. Classically, diagnosis is made with elevation of alkaline phosphatase, demonstration of circulating antimitochondrial antibody, and if performed: asymmetric destruction/nonsupperative cholangitis of intralobular bile ducts on biopsy. Disease pathogenesis is complex and results from innate and adaptive (cell-mediated and humoral) responses that lead to inflammation of biliary duct epithelium. Ongoing damage is amplified and sustained through bile acid toxicity. Use of weight based (13-15mg/kg) ursodeoxycholic acid is well established in retarding disease progression and improving survival; however, is ineffective in achieving complete biochemical remission in many. Recently, a Farnesoid X Receptor agonist, obeticholic acid, has been approved for use. A number of ongoing clinical studies are underway to evaluate utility of fibric acid derivatives, biologics, antifibrotics, and stem cells as monotherapy or in combination with ursodeoxycholic acid for primary biliary cholangitis. The aim of this review is to discuss disease pathogenesis and highlight rationale/implications for both established and novel therapeutics.

OBJECTIVE: The aim of this systematic review was to perform a meta-analysis of randomized controlled trials (RCTs) examining the efficacy of fibrate therapy in reducing plasma concentration or activity of plasminogen activator inhibitor 1 (PAI-1).
METHODS: Scopus and MEDLINE databases were searched (up to October 15, 2014) to identify RCTs investigating whether fibrates lower plasma PAI-1 concentration or activity. A random-effects model and the generic inverse variance method were used for quantitative data synthesis. Sensitivity analyses were conducted using the one-study remove approach. Random-effects meta-regression was performed to assess the impact of potential moderators on the estimated effect sizes.
RESULTS: A total of 14 RCTs examining the effects of gemfibrozil (6 trials), bezafibrate (4 trials), and fenofibrate (5 trials) were included. Meta-analysis suggested that fibrate therapy did not significantly reduce plasma PAI-1 concentration (weighed mean difference [WMD]: -11.39 ng/mL, 95% CI: -26.64, 3.85, p=0.143) or activity (WMD: 2.02 U/mL, 95% CI: -0.87, 4.90, p=0.170). These results remained unchanged after subgroup analysis according to duration of treatment (<12 and ≥12 weeks) and type of fibrate administered (fenofibrate, bezafibrate or gemfibrozil). The estimated effects of fibrate therapy on plasma concentration and activity of PAI-1 were independent of treatment duration and changes in plasma triglyceride levels in the meta-regression analysis.
CONCLUSIONS: This meta-analysis of RCTs suggested that fibrate therapy does not reduce plasma concentration or activity of PAI-I. The putative benefits of fibrate therapy in patients with cardiovascular disease appear to be exerted via mechanisms independent of effects on PAI-1.

BACKGROUND: Several lines of evidence have indicated the insulin-sensitizing, anti-diabetic and anti-atherosclerotic properties of adiponectin, as well as the inverse association between circulating levels of this adipokine and development of cardiovascular outcomes. Improvement of adiponectin status has been reported as a pleiotropic effect of fibrate therapy, but the findings have not been conclusive.
OBJECTIVE: To systematically review and meta-analyze available evidence from randomized placebo-controlled trials (RCTs) on the impact of fibrate therapy on circulating levels of adiponectin.
METHODS: A comprehensive literature search in Medline was carried out to identify RCTs comparing the effect of fibrate therapy vs. placebo on circulating concentrations of adiponectin. A meta-analysis of eligible studies was performed using a random-effects model. Quality assessment, sensitivity analysis and publication bias evaluations were conducted using standard methods.
RESULTS: Twelve RCTs comprising 443 cases and 437 controls met the selection criteria for systematic review, out of which 9 RCTs (399 cases and 401 controls) were included in the meta-analysis. Quantitative data synthesis revealed a significant effect for fibrate therapy in increasing circulating adiponectin levels (weighed mean difference: 0.38 μg/mL; 95% confidence interval: 0.13-0.63 μg/mL; p = 0.003). The effect size remained statistically significant when restricting the analysis to fenofibrate trials [0.31 (0.21-0.42) μg/mL; p < 0.00001). The observed effect was robust in sensitivity analyses and independent of fibrate dose. Imputation for potential missing studies led to the estimation of a greater effect size for fibrate therapy [0.53 (0.24-0.82) μg/mL].
CONCLUSIONS: The present meta-analysis suggests that fibrate therapy increases circulating levels of adiponectin. Whether increase in adiponectin levels contributes to reduction of cardiovascular effects in subjects with dyslipidemia treated with fibrates merits further investigation.

Current lipid management guidelines are focused on decreasing low-density lipoprotein (LDL-C) levels as the primary target for reducing coronary heart disease (CHD) risk. Yet, many recent studies suggest that low levels of high-density lipoprotein (HDL-C) are a major independent risk factor for cardiovascular diseases. According to several clinical trials, a 1% increase in HDL-C is associated with a 0.7%-3% decrease in CHD events. The direct link between high levels of triglycerides (TG) and CHD, on the other hand, is less well defined. A large reduction in TG is needed to show a difference in CHD events, especially in men. Evidence for a shift in lipid management toward targeting both LDL-C and HDL-C as primary targets for therapy is presented. Currently, the 3-hydroxy-3-methylgutaryl coenzyme A reductase inhibitors (HMG-CoA reductase inhibitors) have proven to significantly decrease LDL-C levels, reduce CHD morbidity/mortality and improve overall survival. However, improvement of survival with statins may be due to other pleiotropic effects beyond LDL-C lowering. Fibric acid derivatives and niacin are primarily used to increase HDL-C levels, although with side effects. Future therapies targeting HDL-C may have profound results on reducing CHD morbidity and mortality. This article highlights existing and future targets in lipid management and is based on available clinical data. There is an urgent need for new treatments using a combination of drugs targeting both LDL-C and HDL-C. Such treatments are expected to have a superior outcome for dyslipidemia therapy, along with TG management.