Comparative effects of gemfibrozil and clofibrate in type III hyperlipoproteinemia

Characterization and interactions between piperine and ezetimibe in their Anti-hyperlipidemic efficacy using Biopharmaceutics and Pharmacokinetics

BACKGROUND

Piperine, a secondary metabolite, affects the antihyperlipidemic effect of Ezetimibe (EZ). Hyperlipidemia is one of the independent risk factors for cardiovascular disorders such as atherosclerosis. Antihyperlipidemic drugs are essential for reducing cardiovascular events and patient mortality. Our study aimed to improve the solubility of EZ, a lipid-lowering drug that belongs to BCS II and has low solubility. Piperine, a bioenhancer, can increase the bioavailability of other pharmaceuticals without modifying their fundamental characteristics or enhancing their efficacy. The objective of this study was to increase the bioavailability of EZ while also improving its potency and reducing its toxicity by using piperine as a bioenhancer. Therefore, rats were given piperine combined with EZ, and their antihyperlipidemic activity was assessed while fed a high-fat diet.

METHOD

The in vivo antihyperlipidemic effect of EZ with piperine was assessed at doses of 10 and 5-20 mg/kg b.w. The evaluation was conducted using propylthiouracil-induced and triton X-100-induced hyperlipidemia in rats. Give 400 mg/kg body weight of propylthiouracil along with piperine. Serum levels of total cholesterol (TC) (p < 0.01), triglycerides (TG) (p < 0.01), low-density lipoprotein (LDL) (p < 0.01), and very low-density lipoprotein (VLDL) (p < 0.01) all went up significantly. Additionally, it led to the induction of high-density lipoprotein (HDL) (p < 0.01). Administration of Triton X-100 via intraperitoneal injection at a single dose resulted in an elevation of lipid levels.

RESULTS

Lower levels of high-density lipoprotein (LDL), total cholesterol (TC), triglycerides (TG), and very low-density lipoprotein (VLDL) were significantly reduced by EZ at 10 mg/kg b.w. and piperine at 20 mg/kg b.w., respectively (p < 0.01 and p < 0.05). Liver histology studies provided further evidence supporting the present findings. Areas of concentrated periportal lymphocytes and hepatocytes formed a cord pattern in rats with hyperlipidaemia. It seemed like the hepatocytes, periportal area, and centrilobular part of the liver were all normal in the group who had the treatment. An analysis of the EZ plasma drug concentration with time was carried out in a research. The medication's most effective concentration (Cmax) was determined to be within 4 h after delivery, and The quantified concentration of the active medication was detectable in the bloodstream for 24 h.

CONCLUSION

In combination with piperine, EZ has demonstrated significant antioxidant and antihyperlipidemic effects. This indicates that EZ could be further utilised for treating hyperlipidemia and atherosclerosis due to its potential to boost the bioavailability and oral absorption of the drug.

The Role of Triglyceride-rich Lipoproteins and Their Remnants in Atherosclerotic Cardiovascular Disease

Atherosclerotic cardiovascular disease (ASCVD) is the world's leading cause of death. ASCVD has multiple mediators that therapeutic interventions target, such as dyslipidaemia, hypertension, diabetes and heightened systemic inflammatory tone, among others. LDL cholesterol is one of the most well-studied and established mediators targeted for primary and secondary prevention of ASCVD. However, despite the strength of evidence supporting LDL cholesterol reduction by multiple management strategies, ASCVD events can still recur, even in patients whose LDL cholesterol has been very aggressively reduced. Hypertriglyceridaemia and elevated levels of triglyceride-rich lipoproteins (TRLs) may be key contributors to ASCVD residual risk. Several observational and genetic epidemiological studies have highlighted the causal role of triglycerides within the TRLs and/or their remnant cholesterol in the development and progression of ASCVD. TRLs consist of intestinally derived chylomicrons and hepatically synthesised very LDL. Lifestyle modification has been considered the first line intervention for managing hypertriglyceridaemia. Multiple novel targeted therapies are in development, and have shown efficacy in the preclinical and clinical phases of study in managing hypertriglyceridaemia and elevated TRLs. This comprehensive review provides an overview of the biology, pathogenicity, epidemiology, and genetics of triglycerides and TRLs, and how they impact the risk for ASCVD. In addition, we provide a summary of currently available and novel emerging triglyceride-lowering therapies in development.

Enhanced antihyperlipidemic potential of gemfibrozil under co-administration with piperine

Gemfibrozil is a well-known potent antihyperlipidemic drug with the capacity to lower triglyceride and cholesterol levels, which are responsible for most cardiovascular and cerebrovascular diseases. In addition, gemfibrozil has a potent activity at elevating the high density lipoprotein levels. However, this drug has a very short half-life of about 2 ​h and toxicity is observed in the liver as the dose increases. The drug piperine has the capacity to enhance the bioavailability of other drugs without altering their basic properties as well as improving their activity. In this study, we aimed to enhance the bioavailability of gemfibrozil as well as making it more potent and less toxic by applying piperine as a bio-enhancer. Thus, piperine was co-administered to rats with gemfibrozil and the antihyperlipidemic activity was tested when fed on a high fat diet. The results showed that co-administration of gemfibrozil with piperine decreased the elevated triglyceride and cholesterol levels to normal, and they performed significantly better than the individual drugs. Weight gain was controlled effectively by drug administration together with piperine compared with other groups. Hepatic function analyses demonstrated that the potentiation of gemfibrozil did not alter the hepatic function but instead it improved significantly by normalizing the elevated serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, and alkaline phosphatase levels. The plasma drug concentration of gemfibrozil was studied over time, where the enhanced activity of the drug reached its C_max within 1 ​h of administration and the activated drug level was observed in the blood for 4 ​h.

•

Gemfibrozil is a potent antihyperlipidemic drug with a short half-life.

•

Piperine is used as a natural bio-enhancer to improve the activities of many drugs.

•

Lipid lowering activity of gemfibrozil enhanced by administration with piperine.

•

Piperine enhanced the liver function and plasma concentration of gemfibrozil.

•

Peak plasma concentration of gemfibrozil improved within 1 ​h.

New nicotinic acid-based 3,5-diphenylpyrazoles: design, synthesis and antihyperlipidemic activity with potential NPC1L1 inhibitory activity

Nicotinic acid hydrazide was incorporated into new 4,5-dihydro-5-hydroxy-3,5-diphenylpyrazol-1-yl derivatives. Compounds 6a-h were synthesized, and their antihyperlipidemic activity was evaluated in high cholesterol diet-fed rat model. Compounds 6e, 6f were found to decrease the levels of serum total cholesterol by 14-19% compared to control group. Total triglycerides were also reduced by 24-28% and LDL cholesterol by 16%. As expected from parent niacin, compounds 6e and 6f caused an elevation of HDL cholesterol by 33-41%. Docking study supported the ability of designed compounds to block NPC1L1 active site in a manner similar to that observed with ezetimibe.

Long term efficacy and safety of atorvastatin in the treatment of severe type III and combined dyslipidaemia

BACKGROUND

Fibric acid derivatives and HMG-CoA reductase inhibitors are effective in combination for treating patients with familial dysbetalipoproteinaemia and severe combined dyslipidaemia, but combination therapy affects compliance and increases the risk of side effects.

AIM

To evaluate the efficacy and safety of monotherapy with atorvastatin, an HMG-CoA reductase inhibitor with superior efficacy in lowering low density lipoprotein cholesterol and triglyceride concentrations, in patients with dysbetalipoproteinaemia and severe combined dyslipidaemia.

METHODS

Atorvastatin was tested as single drug treatment in 36 patients with familial dysbetalipoproteinaemia and 23 patients with severe combined dyslipidaemia.

RESULTS

After 40 weeks of 40 mg atorvastatin treatment decreases in total cholesterol, triglycerides, and apolipoprotein B of 40%, 43%, and 41%, respectively, were observed in the combined dyslipidaemia group, and of 46%, 40%, and 43% in the dysbetalipoproteinaemic patients. Target concentrations of total cholesterol (< 5 mmol/l) were reached by 63% of the patients, and target concentrations of triglycerides (< 3.0 mmol/l) by 66%. Treatment with atorvastatin was well tolerated and no serious side effects were reported.

CONCLUSIONS

Atorvastatin is very effective as monotherapy in the treatment of familial dysbetalipoproteinaemia and severe combined dyslipidaemia.

Changes in isoprenoid lipid synthesis by gemfibrozil and clofibric acid in rat hepatocytes

We studied whether gemfibrozil and clofibric acid alter isoprenoid lipid synthesis in rat hepatocytes. After incubation of the cells with the agent for 74 hr, [(14)C]acetate or [(3)H]mevalonate was added, and the cells were further incubated for 4 hr. Gemfibrozil and clofibric acid increased ubiquinone synthesis from [(14)C]acetate and [(3)H]mevalonate. The effect of gemfibrozil was greater than that of clofibric acid. Also, gemfibrozil decreased dolichol synthesis from [(14)C]acetate and [(3)H]mevalonate. However, clofibric acid increased dolichol synthesis from [(3)H]mevalonate. Gemfibrozil decreased cholesterol synthesis from [(14)C]acetate and [(3)H]mevalonate. Clofibric acid decreased cholesterol synthesis from [(14)C]acetate, but did not affect synthesis from [(3)H]mevalonate. These results suggest that both agents, at different rates, activate the synthetic pathway of ubiquinone, at least from mevalonate. Gemfibrozil may inhibit the synthetic pathway of dolichol, at least from mevalonate. Contrary to gemfibrozil, clofibric acid may activate the synthetic pathway of dolichol from mevalonate. Gemfibrozil may inhibit the synthetic pathway of cholesterol from mevalonate in addition to the pathway from acetate to mevalonate inhibited by both agents.

Mechanism of action of fibrates on lipid and lipoprotein metabolism

Treatment with fibrates, a widely used class of lipid-modifying agents, results in a substantial decrease in plasma triglycerides and is usually associated with a moderate decrease in LDL cholesterol and an increase in HDL cholesterol concentrations. Recent investigations indicate that the effects of fibrates are mediated, at least in part, through alterations in transcription of genes encoding for proteins that control lipoprotein metabolism. Fibrates activate specific transcription factors belonging to the nuclear hormone receptor superfamily, termed peroxisome proliferator-activated receptors (PPARs). The PPAR-alpha form mediates fibrate action on HDL cholesterol levels via transcriptional induction of synthesis of the major HDL apolipoproteins, apoA-I and apoA-II. Fibrates lower hepatic apoC-III production and increase lipoprotein lipase--mediated lipolysis via PPAR. Fibrates stimulate cellular fatty acid uptake, conversion to acyl-CoA derivatives, and catabolism by the beta-oxidation pathways, which, combined with a reduction in fatty acid and triglyceride synthesis, results in a decrease in VLDL production. In summary, both enhanced catabolism of triglyceride-rich particles and reduced secretion of VLDL underlie the hypotriglyceridemic effect of fibrates, whereas their effect on HDL metabolism is associated with changes in HDL apolipoprotein expression.

Peroxisome proliferator-activated receptor alpha-isoform deficiency leads to progressive dyslipidemia with sexually dimorphic obesity and steatosis

The alpha-isoform of the peroxisome proliferator-activated receptor (PPARalpha) is a nuclear transcription factor activated by structurally diverse chemicals referred to as peroxisome proliferators. Activators can be endogenous molecules (fatty acids/steroids) or xenobiotics (fibrate lipid-lowering drugs). Upon pharmacological activation, PPARalpha modulates target genes encoding lipid metabolism enzymes, lipid transporters, or apolipoproteins, suggesting a role in lipid homeostasis. Transgenic mice deficient in PPARalpha were shown to lack hepatic peroxisomal proliferation and have an impaired expression and induction of several hepatic target genes. Young adult males show hypercholesterolemia but normal triglycerides. Using a long term experimental set up, we identified these mice as a model of monogenic, spontaneous, late onset obesity with stable caloric intake and a marked sexual dimorphism. Serum triglycerides, elevated in aged animals, are higher in females that develop a more pronounced obesity than males. The latter show a marked and original centrilobular-restricted steatosis and a delayed occurrence of obesity. Fat cells from their liver express substantial levels of PPARgamma2 transcripts when compared with lean cells. These studies demonstrate, in rodents, the involvement of PPARalpha nuclear receptor in lipid homeostasis, with a sexually dimorphic control of circulating lipids, fat storage, and obesity. Characterization of this pathological link may help to delineate new molecular targets for therapeutic intervention and could lead to new insights into the etiology and heritability of mammalian obesity.

Clinical pharmacokinetics of fibric acid derivatives (fibrates)

Beginning with the description of clofibrate in 1962, derivatives of fibric acid (fibrates) have been used clinically to treat dyslipidaemias. Subsequently, gemfibrozil, fenofibrate, bezafibrate, ciprofibrate and long-acting forms of gemfibrozil, fenofibrate and bezafibrate have been developed. Clinically, this class of drugs appears to be most useful in lipoprotein disorders characterised by elevations of very low density lipoprotein and plasma triglycerides, which are often accompanied by reductions in high density lipoprotein (HDL) levels. The principal effects are a reduction in triglyceride and increase in HDL levels, with increases in the activity of hepatic lipase and lipoprotein lipase. There is some reduction of low density lipoprotein (LDL), lipoprotein (a), fibrinogen and uric acid. As a class, these drugs are generally well absorbed from the gastrointestinal tract (immediate-acting fenofibrate being the exception) and display a high degree of binding to albumin. Fibrates are metabolised by the hepatic cytochrome P450 (CYP) 3A4. All members of this class are primarily excreted via the kidneys and display some increase in plasma half-life in individuals with severe renal impairment. The long-acting forms of gemfibrozil and bezafibrate have pharmacokinetic properties similar to those of their immediate-acting parent compounds. The long-acting form of fenofibrate, produced by the process of micronisation, has increased oral bioavailability with less variability in absorption compared with the immediate-acting form of fenofibrate. Drug interactions are seen with other drugs that share a high degree of binding to albumin or are metabolised by CYP3A4. Clinically the most important and most commonly reported drug interactions are with HMG-CoA reductase inhibitors (lovastatin, simvastatin, pravastatin and fluvastatin), warfarin, cyclosporin and oral hypoglycaemic agents [including metformin, tolbutamide and glibenclamide (glyburide)]. The main potential for drug interactions is with drugs or compounds that are metabolised by or affect CYP3A4, including imidazoles, grapefruit juice, erythromycin, mibefradil and others.

Beta-very low density lipoprotein induces triglyceride accumulation through receptor mediated endocytotic pathway in 3T3-L1 adipocytes

To elucidate the mechanism of triglyceride (TG) accumulation in adipocytes induced by TG-rich lipoproteins, we examined the effect of beta-very low density lipoprotein (beta-VLDL) on TG accumulation in 3T3-L1 adipocytes. Beta-VLDL did not induce TG accumulation in 3T3-L1 preadipocytes but in 3T3-L1 adipocytes. TG accumulation was significantly inhibited by cytochalasin B, an inhibitor of receptor mediated endocytosis. In contrast, cytochalasin B did not inhibit free fatty acid induced TG accumulation in adipocytes. The binding of [125I]beta-VLDL to preadipocytes was inhibited completely by both beta-VLDL and LDL. In sharp contrast, the binding of [125I]beta-VLDL to adipocytes was inhibited completely by beta-VLDL, but partially by LDL. The VLDL receptor mRNA was only expressed in adipocytes. These results suggest that beta-VLDL induced TG accumulation in adipocytes may be mediated through the VLDL receptor pathway.

Effects of gemfibrozil administration on very low density lipoprotein receptor mRNA levels in rabbits

To elucidate the regulation of very low density lipoprotein (VLDL) receptor gene expression, we administered to rabbits for 14 days gemfibrozil, a fabric acid derivative and a lipid lowering drug that is also included among peroxisome proliferators. VLDL receptor mRNA levels were examined by Northern blot analysis. The VLDL receptor mRNA levels in retroperitoneal adipose tissue and in gastrocnemius muscle were increased 6.9-fold and 3.7-fold, respectively, with gemfibrozil treatment, but no marked changes were observed in the heart, the organ in which VLDL receptor is most highly expressed. In the liver, VLDL receptor mRNA was not detected either before or after gemfibrozil administration. Lipoprotein lipase (LPL) and long-chain acyl coenzyme A synthetase (ACS) mRNA levels were also increased in parallel in adipose tissue. The enhanced expression of VLDL receptor mRNA may contribute to the increase of triglyceride-rich lipoprotein catabolism in peripheral tissues such as adipose tissue and muscles.