Effect of combined therapy with bezafibrate and cholestyramine on low-density lipoprotein metabolism in type IIa hypercholesterolemia

Clinical utility of bile acid sequestrants in the treatment of dyslipidemia: a scientific review

Bile acid sequestrants (BAS) continue to command a position in the treatment of dyslipidemias 25 years after their introduction. Partial diversion of the enterohepatic circulation using BAS depletes the endogenous bile acid pool by approximately 40%, thus stimulating an increase in bile acid synthesis from cholesterol, which lowers low-density lipoprotein cholesterol (LDL-C) by 15 to 26%. Three BAS are currently used for treating hypercholesterolemia in the United States: the conventional sequestrants, cholestyramine and colestipol, and the specifically engineered BAS, colesevelam hydrochloride (HCl). Compared with conventional BAS, colesevelam HCl has enhanced specificity, greater affinity, and higher capacity for binding bile acids, due to its polymer structure engineered for bile acid sequestration. BAS are not absorbed by the intestine and thus have no systemic drug-drug interactions, but may interfere with the absorption of some drugs. Although BAS monotherapy effectively lowers LDL-C, combination therapy, especially with BAS and statins, is becoming increasingly common due to complementary mechanisms of action. Low-dose statin plus BAS combinations lead to greater or similar LDL-C reductions compared with high-dose statin monotherapy and may have a better safety profile. Combinations of BAS with nonstatin lipid-lowering agents, including niacin, fibrates, and cholesterol absorption inhibitors, may be useful in those patients who require intensive lipid-lowering, but are statin intolerant. BAS treatment can significantly reduce coronary artery disease (CAD) progression and the risk of CAD-associated outcomes. It is also becoming clear that BAS and other therapies that manipulate the bile acid synthetic pathway may have clinically useful therapeutic effects on other metabolic disorders including type 2 diabetes.

Role of the enterohepatic circulation of bile salts in lipoprotein metabolism

The enterohepatic circulation of bile salts and cholesterol plays a central role in maintaining whole body cholesterol homeostasis. Hepatic lipoprotein metabolism is reviewed and the role of disturbances in bile salt metabolism in the pathogenesis of dyslipidemias is discussed. Further, the manipulation of bile salt metabolism to treat dyslipidemia is reviewed.

Effects of simvastatin on plasma lipoprotein subfractions, cholesterol esterification rate, and cholesteryl ester transfer protein in type II hyperlipoproteinemia

We investigated the effects of simvastatin on plasma levels of lipoprotein subfractions, cholesterol esterification rates and activities of cholesteryl ester transfer protein in 28 patients with type II hyperlipoproteinemia (i.e., nonfamilial hyperlipoproteinemia type IIa and type IIb, and heterozygous familial hypercholesterolemia (FH)). Plasma levels of VLDL-cholesterol (C) and VLDL-triglyceride (TG) were significantly reduced overall by 12.9 +/- 58.0% (mean +/- S.D.; P < 0.05) and 4.2 +/- 54.2% (P < 0.05) respectively, but not in FH. Plasma levels of IDL-C and IDLT-G were decreased overall by 23.2 +/- 47.5% (P < 0.001) and 12.3 +/- 49.7% (P < 0.05), respectively, again mainly due to decreases seen in nonfamilial type II hyperlipoproteinemia. Plasma levels of LDL1 (1.019 < d < 1.045)-C and LDL1-TG were significantly reduced by 33.1 +/- 12.9% (P < 0.001) and 23.3 +/- 24.7% (P < 0.001), respectively. Plasma levels of LDL2 (1.045 < d < 1.063)-C were significantly reduced by 22.9 +/- 18.1% (P < 0.001) overall but not in FH. Gradient PAGE showed no consistent changes in the distribution of LDL particles. Thus, plasma levels of all apo B-containing lipoprotein subfractions were reduced by simvastatin, but its effects varied among the three subgroups. Cholesterol esterification rates were suppressed by 9.3 +/- 19.7% (P < 0.01) and activities of cholesteryl ester transfer protein were reduced by 30.6 +/- 21.5% (P < 0.001). Changes in CETP activity and in plasma levels of cholesterol in lipoprotein subfractions were not correlated. Thus, the changes in distribution of lipoprotein subfractions were not due mainly to CETP suppression.

Effects of bezafibrate therapy on subfractions of plasma low-density lipoprotein and high-density lipoprotein, and on activities of lecithin:cholesterol acyltransferase and cholesteryl ester transfer protein in patients with hyperlipoproteinemia

We investigated the effects of 12 weeks of bezafibrate treatment on plasma lipoprotein subfraction levels and on activities of LCAT and CETP in 25 patients with hyperlipoproteinemia. Bezafibrate reduced plasma levels of VLDL-TC and VLDL-TG by 69% and 66% (P < 0.001) and plasma levels of IDL-TC and IDL-TG were decreased by 37% and 31% (P < 0.01). Bezafibrate had no significant effects on plasma levels of LDL1 (1.019 < d < 1.045)-TC and LDL1-TG in the study population as a whole but significantly increased the plasma level of LDL1-TC in the subgroup of 9 patients with type IV hyperlipoproteinemia. Bezafibrate reduced plasma levels of LDL2 (1.045 < d < 1.063)-TC, LDL2-TG by 48% and 44% (P < 0.001) in both type II and type IV hyperlipoproteinemic patients. Gradient polyacrylamide gel electrophoresis revealed a decrease in small LDL particles. Bezafibrate did not affect the plasma level of HDL2-TC but reduced the HDL2-TG concentration significantly (P < 0.001). Bezafibrate increased the plasma level of HDL3-TC by 37% and reduced the HDL3-TG level significantly by 20% (P < 0.001). Gradient polyacrylamide gel electrophoresis revealed an increase in HDL3a and a decrease in HDL2a. Bezafibrate suppressed the activities of LCAT and CETP by 21% (P < 0.001) and 17% (P < 0.01), respectively. The bezafibrate-induced decrease in plasma levels of small, heavy LDL might be related to its inhibition of LCAT and CETP activities which resulted in suppression of heteroexchange of HDL-EC with triglyceride in large, light LDL. The bezafibrate-induced increase in large HDL3 (HDL3a) could not be explained solely by its suppression of LCAT and CETP activities. The decrease of plasma small, heavy LDL as well as TG-rich lipoproteins by bezafibrate seems to be beneficial for prevention of atherosclerotic diseases.

Raising HDL cholesterol with low-dose nicotinic acid and bezafibrate: preliminary experience

Nicotinic acid is an effective agent for elevating HDL cholesterol but is limited by side effects. In order to improve tolerance and lipid levels, we combined low-dose nicotinic acid with bezafibrate. We gave low-dose (mean 435 mg/day) nicotinic acid to 37 patients with low HDL cholesterol, bezafibrate (mean 476 mg/day) to 58 patients with elevated total cholesterol and both agents (mean nicotinic acid 435 mg/day and bezafibrate 512 mg/day) to 25 patients with low HDL cholesterol and elevated total cholesterol. A total of 53 additional patients were followed as controls. Three intervals of treatment were studied: 0-6, 6-12 and > 12 months. The combination of drugs resulted in significant (P < 0.05) percentage changes in total cholesterol, triglycerides and total/HDL cholesterol compared to nicotinic acid alone and significant (P < 0.04) percentage changes in HDL cholesterol compared to bezafibrate alone. It is concluded that low doses of nicotinic acid may result in significant changes in HDL cholesterol; when combined with bezafibrate significant alterations in total cholesterol, triglycerides and total/HDL cholesterol also result.

The hypocholesterolemic effect of an antacid containing aluminum hydroxide

STUDY OBJECTIVE

To evaluate the efficacy, safety, and hypocholesterolemic effect of an aluminum hydroxide-containing antacid in hypercholesterolemic individuals.

DESIGN

A prospective, randomized, double-masked, placebo-controlled phase of 2 months' duration, followed by an open-design treatment phase of 2 months' duration and a washout phase of 2 months' duration.

SETTING

Family practice clinics of two rural communities (kibbutzim) in Israel.

PATIENTS

Fifty-six men and women with hypercholesterolemia (type IIa or IIb). Fifty individuals completed the study.

INTERVENTION

After 2 months of dietary modification (low-fat, low-cholesterol diet), the participants were randomized into two matched groups. Group 1 (28 participants) was treated for 2 months with a chewable antacid tablet containing simethicone, magnesium hydroxide, and 113 mg of aluminum hydroxide per tablet, at a dose of two tablets four times daily. Group 2 (22 participants) was given a similar number of placebo tablets for 2 months. During the following 2 months, both groups received the antacid at the above dose.

MEASUREMENTS AND MAIN RESULTS

Lipoprotein levels were evaluated at baseline and every 2 months thereafter for 6 months. Compared with pretreatment levels, Group 1 experienced a decrease in low-density lipoprotein cholesterol (LDL-C) of 9.8% after 2 months (p less than 0.001) and 18.5% after 4 months (p less than 0.001). Compared with Group 2, the decrease in LDL-C in Group 1 was 6.2% at the end of the 2-month double-masked, placebo phase. Although the high-density lipoprotein cholesterol (HDL-C) was also reduced in Group 1 at the end of 4 months of therapy (10.2%), the HDL-C/LDL-C ratio increased by 13% during the same interval (p less than 0.05). The treatment was well tolerated, with minimal side effects.

CONCLUSIONS

An aluminum hydroxide-containing antacid reduces LDL-C in hypercholesterolemic individuals. Although HDL-C was also reduced to a lesser extent, the overall atherogenic index was improved. Further studies should be conducted to evaluate the long-term safety and efficacy of antacids containing aluminum hydroxide in hypercholesterolemic patients.

Effects of gemfibrozil and other fibric acid derivatives on blood lipids and lipoproteins

Fibric acid derivatives (FADs) are a class of drugs that have been shown to reduce the production of very low-density lipoprotein (VLDL) while enhancing VLDL clearance due to the stimulation of lipoprotein lipase activity. The drugs can reduce plasma triglyceride levels while raising high-density lipoprotein (HDL) cholesterol levels. Their effects on low-density lipoprotein (LDL) cholesterol levels are less marked and more variable. There is evidence that oral gemfibrozil (Lopid, Parke-Davis, Morris Plains, NJ) can reduce the risk of serious coronary events, specifically in those patients who had elevations of both LDL cholesterol levels and total plasma triglyceride levels with lower HDL cholesterol levels. Newer FADs (bezafibrate, ciprofibrate, fenofibrate) have been shown to have greater efficacy in reducing LDL cholesterol than gemfibrozil but, in general, these drugs are not as effective as the other primary drugs used to lower LDL levels. The FADs are also used to treat adult patients with very high levels of triglycerides who have pancreatitis and whose disease cannot be managed with dietary therapy. The FADs are well tolerated, with dyspepsia and abdominal pain the most common adverse effects. A small risk of cholelithiasis exists with these drugs, and caution should be used when combining these drugs with HMG-CoA reductase inhibitors because the combination increases the incidence of hyperlipidemic myositis and rhabdomyolysis.