Gemfibrozil-induced decrease in serum ubiquinone and alpha- and gamma-tocopherol levels in men with combined hyperlipidaemia

Biosynthesis, Deficiency, and Supplementation of Coenzyme Q

Originally identified as a key component of the mitochondrial respiratory chain, Coenzyme Q (CoQ or CoQ₁₀ for human tissues) has recently been revealed to be essential for many different redox processes, not only in the mitochondria, but elsewhere within other cellular membrane types. Cells rely on endogenous CoQ biosynthesis, and defects in this still-not-completely understood pathway result in primary CoQ deficiencies, a group of conditions biochemically characterised by decreased tissue CoQ levels, which in turn are linked to functional defects. Secondary CoQ deficiencies may result from a wide variety of cellular dysfunctions not directly linked to primary synthesis. In this article, we review the current knowledge on CoQ biosynthesis, the defects leading to diminished CoQ₁₀ levels in human tissues and their associated clinical manifestations.

Coenzyme Q10: A Review

Coenzyme Q10 (CoQ10) is a provitamin manufactured by the body. It functions as a coenzyme for mitochondrial enzymes. It has been shown to be deficient in patients with cardiovascular disease, cancer, Acquired Immune Deficiency Syndrome (AIDS), muscular dystrophy, spontaneous abortion, male infertility, and periodontal disease. Studies of CoQ10 show preliminary efficacy in the treatment of cardiovascular disease, but there is not enough evidence to date to support its benefit in cancer, AIDS, muscular dystrophy, spontaneous abortion, male infertility and periodontal disease treatments. Additional research is needed to evaluate its benefits in the treatment of these other conditions.

Improved photostability and cytotoxic effect of coenzyme Q10 by its association with vitamin E acetate in polymeric nanocapsules

The present study showed the development of nanocapsules containing the association of the coenzyme Q10 and vitamin E acetate and the evaluation of their effect on in vitro cells culture of malignant glioma and melanoma. In order to investigate if nanocapsules are able to protect coenzyme Q10 from degradation under UVC radiation, a photostability study was carried out. For this, three concentrations of vitamin E acetate were evaluated (1%, 2%, or 3%). Nanocapsules presented suitable physicochemical characteristics and were able to protect coenzyme Q10 from photodegradation. In addition, this protection was influenced by higher vitamin E acetate concentrations, attributing to this oil an important role on coenzyme Q10 photostabilization. Regarding to in vitro citotoxicity assay, nanocapsules containing coenzyme Q10 and 2% vitamin E significantly reduced glioma and melanoma cell viability in 61% and 66%, respectively. In this sense, these formulations represent interesting platforms for the delivery of coenzyme Q10 and vitamin E acetate, presenting effect on the reduction of malignant cells viability.

Kolliphor® HS 15 Micelles for the Delivery of Coenzyme Q10: Preparation, Characterization, and Stability

To enhance the stability of coenzyme Q10 (CoQ10), Kolliphor® HS 15 (HS15) was employed as a carrier to build up a stable CoQ10-loaded micelle delivery system. The impact of micellar compositions, the preparation condition, and the preparation method on size characteristics, the solubilization efficiency, and micellar stability were investigated. The optimal preparation conditions were 1:6, 4, 0.2%, 118°C, and 25 min for CoQ10/HS15 mass ratio, pH value, the concentration of glucose, and the sterilization conditions. Upon these conditions, the particle size, polydispersity index (PDI), zeta potential, the entrapment efficiency, drug loading, and the critical micelle concentration (CMC) of CoQ10-loaded micelles were 19.76 nm, 0.112, -3.405 mV, 99.39%, 13.77%, and 5.623 × 10(-4) g/mL, respectively. Differential scanning calorimetry (DSC) analysis collectively corroborated that CoQ10 was entrapped into the micelles in amorphous form. The release pattern of drug was analyzed and proved to follow the first order. Additionally, the samples were exposed to the temperatures of 30°C for 6 months with more significant impact on their stabilities as compared to 4 and 25°C based on particle size and PDI. Under constant humidity with light protection long-term (25 ± 2°C, relative humidity (RH) 60 ± 10%, 18 months) conditions, there was no variation except minor changes of CoQ10 content of the samples. The shelf life of the micellar samples could be predicted as 24 months based on the stability results. Consequently, the CoQ10-loaded micelles showed excellent stabilities below 25°C as a potential drug candidate for further clinical applications.

Vitamin D Deficiency in Community-Dwelling Elderly Is Not Associated with Age-Related Macular Degeneration

BACKGROUND

Elderly persons are at elevated risk of vitamin D deficiency, which is involved in various health problems. However, its relation with age-related macular degeneration (AMD) is debated.

OBJECTIVES

We investigated factors associated with plasma 25-hydroxyvitamin D [25(OH)D] deficiency and the associations between plasma 25(OH)D concentrations and AMD in elderly subjects.

METHODS

Antioxydants, Lipides Essentiels, Nutrition et maladies OculaiRes (ALIENOR) is a population-based study on eye diseases performed in elderly residents of Bordeaux, France. Plasma 25(OH)D concentrations were assessed from blood samples and categorized as <25 nmol/L (deficiency), 25-49 nmol/L (insufficiency), or ≥50 nmol/L (sufficiency). AMD was classified as: no AMD, early AMD, and late AMD. Associations between baseline characteristics and plasma 25(OH)D status were examined with multinomial logistic regression analysis. Associations between AMD and plasma 25(OH)D status were estimated using generalized estimating equation logistic regressions.

RESULTS

Six hundred ninety-seven subjects with complete data were included. The prevalence of plasma 25(OH)D deficiency and insufficiency were 27.3% and 55.9%, respectively. In multivariate analysis, 25(OH)D deficiency was significantly associated with older age (P = 0.0007), females (P = 0.0007), absence of physical activity (P = 0.01), absence of vitamin D supplementation (P < 0.0001), higher plasma total cholesterol (P = 0.007), use of fibrates (P < 0.0001), lower alcohol consumption (P = 0.02), and season of blood sampling (P < 0.0001). After adjustment for these covariates and dietary omega-3 polyunsaturated fatty acid intake, smoking, and body mass index, no significant associations were found between early AMD and 25(OH)D insufficiency or deficiency (OR: 0.71, P = 0.12; OR: 0.73, P = 0.23, respectively) or with late AMD (OR: 1.04, P = 0.93; OR: 0.74, P = 0.59, respectively).

CONCLUSION

These findings underline the very high prevalence of plasma 25(OH)D deficiency in this elderly population but do not support a specific role for vitamin D in AMD.

Plasma levels of insulin-like growth factor-I, insulin-like growth factor binding protein-1, coenzyme Q10 and vitamin E in female populations from Poland, Serbia and Sweden

Exposure to environmental contaminants such as polycyclic aromatic hydrocarbons (PAHs), life style and nutritional status of a population are important factors that may influence normal serum levels of antioxidants and the insulin-like growth factor system. In this study we examined serum levels of insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-1(IGFBP-1), coenzyme Q10 (CoQ) and vitamin E in healthy female populations (n=4 x 100) aged 19-59 years from Poland (PL), Sweden (SE), Serbia I (SR I) and Serbia II (SR II). The last group lived in an environmental emergency area affected by the bombings of 1999 in Serbia. The Polish and SR I cohorts exhibited low IGFSD-score levels, (-2 to +/-0), compared to females from SE with IGFSD-score 0. In the SR II population, the IGFSD range was between -1 and 1. The IGFBP-1 levels of the Polish and SR I groups were lower than in the Swedish population, while the SR II levels showed a broader distribution, 20-80 microg/l. The CoQ values in the Swedish and Polish samples were around 1 nmol/ml. In contrast, the SR I cohorts exhibited higher concentrations, 1.5-3.5 nmol/ml and the SR II group had extremely low levels, <0.5 nmol/ml. The vitamin E concentrations were similar in the Polish and Swedish populations, 20-40 nmol/ml, while it was twice as high, 40-80 nmol/ml in the SR I and very low in the SR II group, which is half of the Polish and Swedish cohorts. These results suggest that different lifestyles and environmental factors affect both the IGF system and the antioxidants CoQ10 and vitamin E in female populations in Europe. The females living in the polluted area had different patterns of both the IGF and antioxidant systems. These findings may explain differences in morbidity and mortality in these countries.

Combination therapy with an HMG-CoA reductase inhibitor and a fibric acid derivative: a critical review of potential benefits and drawbacks

It has been clearly shown that lowering low density lipoprotein-cholesterol (LDL-C) [most often with an HMG-CoA reductase inhibitor] decreases the risk of a cardiovascular event. However, this risk reduction was, at most, 35% in clinical trials, meaning that many events could not be prevented. Moreover, reaching target lipid values as recommended by the current guidelines is often difficult, mainly in high-risk situations such as secondary prevention or type 2 diabetes mellitus. As the two main classes of lipid-lowering drugs (HMG-CoA reductase inhibitors and fibric acid derivatives) have complementary effects on lipid parameters, it seems logical to combine both treatments particularly in patients with combined hyperlipidemia. In fact, combination therapy with an HMG-CoA reductase inhibitor and a fibric acid derivative induces a further decrease in LDL-C levels compared with monotherapy and improves other lipid values such as high density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) levels. Unfortunately, there are currently no available randomized, prospective clinical data on the reduction of the incidence of cardiovascular events with such a combination. This is mainly because the use of HMG-CoA reductase inhibitor and fibric acid derivative combinations was initially described as dangerous. It is true that such a combination increases the risk of muscle toxicity that already exists with monotherapy. Muscle toxicity can eventually lead to life-threatening rhabdomyolysis and some precautions of use are required; however, the risk seems actually lower than what has been initially reported. The use of combined therapy with an HMG-CoA reductase inhibitor and a fibric acid derivative requires the respect of some rules such as avoiding the prescription in patients with concomitant conditions like renal failure and avoiding the use of gemfibrozil as a fibric acid derivative in such a combination. It is now imperative to design clinical trials to determine the clinical efficacy and precise safety of this combined treatment especially in patients with abnormalities in every parameter of the lipid triad (LDL, HDL and TG) and a high vascular risk such as patients with type 2 diabetes mellitus.

The antioxidant role of coenzyme Q

A number of functions for coenzyme Q (CoQ) have been established during the years but its role as an effective antioxidant of the cellular membranes remains of dominating interest. This compound is our only endogenously synthesized lipid soluble antioxidant, present in all membranes and exceeding both in amount and efficiency that of other antioxidants. The protective effect is extended to lipids, proteins and DNA mainly because of its close localization to the oxidative events and the effective regeneration by continuous reduction at all locations. Its biosynthesis is influenced by nuclear receptors which may give the possibility, in the future, by using agonists or antagonists, of reestablishing the normal level in deficiencies caused by genetic mutations, aging or cardiomyopathy. An increase in CoQ concentration in specific cellular compartments in the presence of various types of oxidative stress appears to be of considerable interest.

Effect of ezetimibe and/or simvastatin on coenzyme Q10 levels in plasma: a randomised trial

BACKGROUND

HMG-CoA reductase inhibitors ('statins') have been associated with a decrease in ubidecarenone (ubiquinone) levels, a lipophilic enzyme also known as coenzyme Q10 (CoQ10), due to inhibition of mevalonate synthesis. There is speculation that a decrease in CoQ10 levels may be associated with statin-induced myopathy. The cholesterol absorption inhibitor ezetimibe increases endogenous cholesterol synthesis. The purpose of this study was to examine (i) the effects of ezetimibe and simvastatin on plasma CoQ10 levels and (ii) whether ezetimibe coadministered with simvastatin abrogates the suggested statin-induced decrease in the CoQ10 plasma levels.

METHODS

Seventy-two healthy male subjects were enrolled in a single-centre, randomised, parallel-group study with three arms. Subjects received ezetimibe 10 mg/day, simvastatin 40 mg/day or the combination of ezetimibe 10 mg/day plus simvastatin 40 mg/day for 14 days.

RESULTS

Baseline CoQ10 (0.99 +/- 0.30 mg/L) levels for the combined groups remained unchanged in the ezetimibe group (0.95 +/- 0.24 mg/L), and significantly decreased in the simvastatin and combination groups (0.82 +/- 0.18 mg/L, p = 0.0002 and 0.7 +/- 0.22 mg/L, p < 0.0001, respectively). There was a correlation between the percentage change in the levels of low-density lipoprotein-cholesterol (LDL-C) and the percentage change in CoQ10 levels in all treatment groups (correlation coefficient [R] = 0.67, p < 0.0001). The ratios of CoQ10 levels to LDL-C levels were significantly increased in all treatment groups (p < 0.0001). CoQ10 level was independent of cholesterol synthesis or absorption markers.

CONCLUSIONS

Simvastatin and the combination of simvastatin and ezetimibe significantly decrease plasma CoQ10 levels whereas ezetimibe monotherapy does not. There is a significant correlation between the CoQ10 level decrease and the decrease in total and LDL-C levels in all three treatment groups, suggesting that the CoQ10 decrease may reflect the decrease in the levels of its lipoprotein carriers and might not be statin-specific. The statin-associated CoQ10 reduction is not abrogated through ezetimibe coadministration. Changes of CoQ10 levels are independent of cholesterol synthesis and absorption.

Extracts of monascusus purpureus beyond statins —Profile of efficacy and safety of the use of extracts of monascus purpureus

Extracts of Monascus purpureus have always been considered a natural source of lovastatin, the precursor of the world's largest selling class of drugs. In actual fact, the fungus contains many other substances (flavonoids, polyunsaturated fats, pyrrolinic compounds etc.) with a wide variety of other actions. The most recent studies have shown that it has an action on the glycemic metabolism, and on the mechanisms of adipogenesis, also an effects on the endothelium and on postprandial vasodilation. These effects are more extensive and complex than those of statins alone. And new strains of Monascus purpureus have recently been patented where the presence of statins is only one of the therapeutic components of the fungus. In particular, the increase in secondary components, such as flavonoids, which coincides with a more complex therapeutic action, probably making the new extracts of Monascus purpureus, the ideal candidate for the treatment of the metabolic syndrome.

Metabolism and function of coenzyme Q

Coenzyme Q (CoQ) is present in all cells and membranes and in addition to be a member of the mitochondrial respiratory chain it has also several other functions of great importance for the cellular metabolism. This review summarizes the findings available to day concerning CoQ distribution, biosynthesis, regulatory modifications and its participation in cellular metabolism. There are a number of indications that this lipid is not always functioning by its direct presence at the site of action but also using e.g. receptor expression modifications, signal transduction mechanisms and action through its metabolites. The biosynthesis of CoQ is studied in great detail in bacteria and yeast but only to a limited extent in animal tissues and therefore the informations available is restricted. However, it is known that the CoQ is compartmentalized in the cell with multiple sites of biosynthesis, breakdown and regulation which is the basis of functional specialization. Some regulatory mechanisms concerning amount and biosynthesis are established and nuclear transcription factors are partly identified in this process. Using appropriate ligands of nuclear receptors the biosynthetic rate can be increased in experimental system which raises the possibility of drug-induced upregulation of the lipid in deficiency. During aging and pathophysiological conditions the tissue concentration of CoQ is modified which influences cellular functions. In this case the extent of disturbances is dependent on the localization and the modified distribution of the lipid at cellular and membrane levels.

Gemfibrozil lowers plasma lipids and increases polyunsaturated fatty acid content and oxidative susceptibility of lipoproteins in hypertriglyceridemia

BACKGROUND

Gemfibrozil is an effective drug in the treatment of hypertriglyceridemia and its effects on morbidity and mortality seem out of proportion to its lipid lowering actions. There is considerable interest in its potential effects on lipoprotein fatty acid composition and consequent effect on oxidative susceptibility. Experimental results are not conclusive regarding whether gemfibrozil alters lipid composition or oxidative susceptibility of lipoproteins in humans. Here we investigate this question using different methodology than employed in previous investigations.

METHODS

Eleven hypertriglyceridemic individuals completed a 12-week course of gemfibrozil therapy (600 mg twice daily) intended to primarily evaluate a new way of assessing lipoprotein susceptibility to oxidation in relation to changes in the fatty acid profile. We measured susceptibility of lipoproteins in the plasma macromolecule fraction to copper-mediated oxidation. In addition, plasma lipids were separated into phospholipid (PL), cholesterol ester (CE) and triglyceride (TG) fractions and the fatty acid composition of these classes determined by gas-liquid chromatography. The relation between changes in lipid concentration, fatty acid composition and oxidative parameters (principally lag time) was examined by correlational analysis.

RESULTS

Triglyceride concentrations and total cholesterol concentrations responded appropriately to gemfibrozil (lowered by 55% and 15%, respectively). Polyunsaturated fatty acid (PUFA) proportion increased significantly in cholesterol ester and phospholipid fractions of plasma lipids at the expense of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). Oxidative parameters also changed significantly. Lag time (LT) and maximal extent of oxidation showed the most significant changes. Lag time, the principle measure of lipoprotein susceptibility to oxidation, was decreased by gemfibrozil. The increase in polyunsaturated fatty acid content in phospholipid and cholesterol ester significantly correlated with decreased lag time.

CONCLUSION

These data support the notion that gemfibrozil increases the proportion of polyunsaturated fatty acids in plasma lipids and that this increase is associated with an increase in lipoprotein oxidative susceptibility as measured by lag time in hypertriglyceridemia.

Coenzyme Q10 and cardiovascular disease: a review

This article provides a comprehensive review of 30 years of research on the use of coenzyme Q10 in prevention and treatment of cardiovascular disease. This endogenous antioxidant has potential for use in prevention and treatment of cardiovascular disease, particularly hypertension, hyperlipidemia, coronary artery disease, and heart failure. It appears that levels of coenzyme Q10 are decreased during therapy with HMG-CoA reductase inhibitors, gemfibrozil, Adriamycin, and certain beta blockers. Further clinical trials are warranted, but because of its low toxicity it may be appropriate to recommend coenzyme Q10 to select patients as an adjunct to conventional treatment.

Cerivastatin-induced rhabdomyolysis: 11 case reports

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are a frequently prescribed class of drugs that are generally well tolerated by most patients. A rare, yet serious side effect associated with these drugs is rhabdomyolysis. Although all HMG-CoA reductase inhibitors can cause this adverse effect, prevalence may differ among specific agents. Over a 16-month period, in three hospitals, 11 patients experienced cerivastatin-induced rhabdomyolysis, but no cases of rhabdomyolysis associated with any other HMG-CoA reductase inhibitors were reported.

Regulation of ubiquinone metabolism

Interest in ubiquinone (UQ) has increased during recent years, mainly because of its antioxidant function and its use as a dietary supplement. However, our knowledge of the biosynthesis, catabolism, and regulation of this lipid in mammalian tissues is quite limited. UQ exhibits a high rate of turnover in all tissues indicating that cells possess efficient metabolic pathways for handling this compound and controlling its tissue levels. Besides reviewing the generally accepted metabolic pathway, alternative synthetic mechanisms are described. The lack of data concerning catabolism and regulation of this compound is emphasized. Reasons for the rather limited uptake of dietary UQ are discussed and alternative mechanisms for its beneficial effects on organ function are suggested. Since appropriate tissue uptake of dietary UQ probably only occurs in deficient states, the definition of partial UQ deficiency and its consequences is urgently needed. The possibility of raising tissue UQ levels by drug treatment or natural metabolites is raised as a choice of preference for the future.

Macromolecular prodrugs. VIII. Synthesis of polymer-gemfibrozil conjugates

Gemfibrozil is covalently linked to two similar polymers: poly[alpha,beta-(N-2-hydroxyethyl-DL-aspartamide)] and poly[alpha,beta-(N-3-hydroxypropyl-DL-aspartamide)]. The synthesised polymer drug conjugates differ in average molecular mass, type of covalent bonding, length of spacer, drug-loading and solubility.