Effects of an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase on serum lipoproteins and ubiquinone-10-levels in patients with familial hypercholesterolemia

Influence of pravastatin, a specific inhibitor of HMG-CoA reductase, on hepatic metabolism of cholesterol

BACKGROUND

Inhibitors of the rate-limiting enzyme of cholesterol biosynthesis, 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase, are now used frequently to treat hypercholesterolemia. We studied the effects of specific inhibition of cholesterol synthesis by one of these agents (pravastatin) on the hepatic metabolism of cholesterol in patients with gallstone disease who were scheduled to undergo cholecystectomy.

METHODS

Ten patients were treated with pravastatin (20 mg twice a day) for three weeks before cholecystectomy; 20 patients not treated served as controls. A liver specimen was obtained from each patient at operation, and the activities of rate-determining enzymes in cholesterol metabolism as well as low-density-lipoprotein (LDL)-receptor binding activity were determined.

RESULTS

Pravastatin therapy reduced plasma total cholesterol by 26 percent and LDL cholesterol by 39 percent (P less than 0.005). Serum levels of free lathosterol, a precursor of cholesterol whose concentration reflects the rate of cholesterol synthesis in vivo, decreased by 63 percent (P less than 0.005), indicating reduced de novo biosynthesis of cholesterol. Microsomal HMG-CoA reductase activity, when analyzed in vitro in the absence of the inhibitor, was increased 11.8-fold (1344 +/- 311 vs. 105 +/- 14 pmol per minute per milligram of protein in the controls; P less than 0.001). The expression of LDL receptors was increased by 180 percent (P less than 0.005), whereas the activities of cholesterol 7 alpha-hydroxylase (which governs bile acid synthesis) and of acyl-coenzyme A:cholesterol O-acyltransferase (which regulates cholesterol esterification) were unaffected by treatment.

CONCLUSIONS

Inhibition of hepatic HMG-CoA reductase by pravastatin results in an increased expression of hepatic LDL receptors, which explains the lowered plasma levels of LDL cholesterol.

The effect of pravastatin in relation to low density lipoprotein receptor activity

Pravastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, suppresses new synthesis of cholesterol via HMG-CoA in hepatocytes. As a result, low density lipoprotein (LDL) receptor activity in the liver is enhanced, which leads to lowering of plasma cholesterol. Inhibitors are shown to be effective in heterozygous familial hypercholesterolaemia (FH). Although FH heterozygotes are defined genetically as possessing half the normal LDL receptor activity, some heterogeneity of LDL receptor activity is observed in these patients. To see whether the effect of an inhibitor is related to LDL receptor activity in each patient, pravastatin was administered to 7 FH heterozygotes for 3 months at a daily dose of 10 mg; their mean LDL receptor activities measured before the therapy were 45.0 +/- 9.9% of the normal control. After medication, mean serum total cholesterol decreased from 349.0 to 279.7 mg/dl (p less than 0.05), and LDL-cholesterol decreased from 272.6 to 207.7 mg/dl (p less than 0.05). A significant correlation between the initial LDL receptor activity and the effect of pravastatin was not proved. However, the pre-treatment level of LDL-cholesterol was positively correlated (r = 0.795) with the absolute decrement of LDL-cholesterol after 3 months (p less than 0.05). This implies that the more LDL-cholesterol was elevated, the more pravastatin was effective.

Plasma cortisol and testosterone in hypercholesterolaemia treated with clofibrate and lovastatin

Plasma testosterone and cortisol concentrations were measured in 32 familial heterozygous hypercholesterolaemic subjects, aged 40-45 years. The subjects were divided into two groups of 16, each containing eight men and eight women. The women had normal menstrual cycles. After a period on placebo, one group of patients was given 40 mg/day lovastatin and the other was given 1500 mg/day clofibrate. Both drugs significantly reduced the plasma cholesterol concentration, however, unlike clofibrate, lovastatin did not decrease plasma levels of testosterone and cortisol. The response to stimulation by adrenocorticotrophic hormone of plasma cortisol and urinary 17-hydroxy levels was significantly reduced by treatment with clofibrate, but unchanged by lovastatin. The different effects produced by the two drugs probably reflect different mechanisms and sites of action.

Reduction in plasma low-density lipoprotein cholesterol and urinary mevalonic acid by lovastatin in patients with heterozygous familial hypercholesterolemia

The effects of lovastatin, an inhibitor of 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMG CoA reductase), on 24-hour urinary excretion rates of mevalonic acid (an intermediate in cholesterol biosynthesis) and plasma low-density lipoprotein (LDL) cholesterol concentrations were evaluated in patients with heterozygous familial hypercholesterolemia (FH). The mean rates of urinary mevalonate excretion of 28 FH patients were initially higher (2.95 +/- 0.29 (+/- SEM) mumols/d) than in 17 control subjects (1.82 +/- 0.12 mumols/d). Patients with FH were treated with sequentially increasing doses of lovastatin (10, 20, 40, and 80 mg daily, taken as a twice daily dosage) for a period of 6 weeks on each dose. When compared to baseline, LDL cholesterol levels fell by 22%, 26%, 30%, and 35% respectively, on these different doses. The mean daily urinary mevalonate excretion decreased from baseline by 19% after 4 weeks on 10 mg daily of lovastatin, 35% on 20 mg, and 31% on 40 mg and 80 mg daily. Similar decreases in urinary mevalonate excretions were observed when patients with FH were treated directly with 40 mg (20 mg twice daily) or 80 mg (40 mg twice daily) mg of lovastatin daily. The magnitude of decrease in LDL cholesterol did not show any significant correlation with the changes in urinary excretion of mevalonic acid. Lovastatin therapy decreases rates of urinary mevalonate excretion (which has previously been shown to reflect rates of cholesterol synthesis) by up to 35% at doses of 20 to 80 mg/d; such a decrease seems unlikely to compromise other important cellular requirements for mevalonate.

Treatment of hypercholesterolemia with the HMG CoA reductase inhibitor, simvastatin

We report the results of a two center study on the use of the HMG Co A reductase inhibitor, simvastatin, in 44 patients suffering from familial hypercholesterolemia or from primary hypercholesterolemia of unknown etiology. The study included two separate phases: Phase I was part of a multicenter, 4-week, placebo-controlled trial; phase II was a 6-month, open extension trial, the object of which was to reduce low density lipoprotein (LDL) cholesterol levels to below the 50th percentile by increasing the dose of simvastatin, by the use of additional lipid-lowering medication, or both. Our phase I results were commensurate with those reported for the entire international cohort of 272 patients, indicating a clear dose-response relationship, with approximately 75% of the maximum reduction in LDL-C levels being achieved with 20 mg/day and over 90% of the maximum being achieved with 40 mg of simvastatin per day. In the open extension trial, the results from the 2 centers were essentially similar. Total cholesterol fell by 29% on the 20 mg/day dose and by 34% on the full dose of 40 mg/day. LDL-C levels were reduced by 40% on the 40 mg/day schedule, and triglycerides also fell to between 20% and 40% below baseline values. HDL-C concentration rose by 14% and 17.6%. The effects of simvastatin were uniform, both within and between the two cohorts. The addition of cholestyramine caused a further substantial reduction in LDL-cholesterol to below 55% of the initial value in four patients, whereas bezafibrate further enhanced the fall in triglycerides and the increase in high-density lipoprotein cholesterol, but had only a slight effect on LDL-C levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Lovastatin in the treatment of multifactorial hyperlipidemia associated with proteinuria

The efficacy and safety of lovastatin as a hypolipidemic agent were evaluated in ten adult patients with secondary hypercholesterolemia due to proteinuria (greater than 2 g/d) and (in seven patients) concurrent corticosteroid therapy. Patients were on a low-cholesterol diet throughout the study. After a 4-week baseline period, patients were randomized to receive either placebo or 10 mg lovastatin twice daily for a period of 6 weeks. The dose of lovastatin was increased to 20 mg twice daily for 6 weeks, and 40 mg twice daily for 6 weeks in the latter group. Those patients who received placebo for the first 6 weeks subsequently received 10, 20, and 40 mg of lovastatin twice daily in a stepped dose regimen, with each dose given for 6 weeks. Lovastatin was well tolerated by all patients and none withdrew from the study. Baseline plasma cholesterol concentrations (390 +/- 20 mg/dL; mean +/- SEM) decreased 22% (P less than 0.003) at the lowest dose of 10 mg twice daily, 27% at 20 mg twice daily, and 33% at 40 mg twice daily. Baseline plasma triglycerides decreased by 25% (P less than 0.05) at the highest dosage. Concentrations of low-density lipoprotein (LDL) cholesterol fell by 29%, 34%, and 45% on doses of 10, 20, and 40 mg of lovastatin twice daily. Concentrations of high-density lipoprotein (HDL) cholesterol increased slightly. Serum creatinine concentrations and proteinuria were not affected by lovastatin therapy. We conclude that lovastatin was a well-tolerated and extremely effective hypocholesterolemic agent in patients with persistent secondary hypercholesterolemia associated with proteinuria or proteinuria and concurrent corticosteroid therapy.

Guar gum and gemfibrozil--an effective combination in the treatment of hypercholesterolaemia

Twenty-nine hypercholesterolaemic patients, treated for one year with gemfibrozil but being still hypercholesterolaemic (serum total cholesterol greater than or equal to 6.25 mmol/l) were included in a double-blind trial to evaluate the hypocholesterolaemic effects of gemfibrozil-guar gum combination (GE + GU) vs. gemfibrozil-placebo combination (GE + PL) using a cross-over study design. The patients were treated with gemfibrozil on a constant dosage (range 900-1200 mg/day) during the entire trial. After a 4-week run-in period on GE + PL treatment the patients were randomly allocated to 2 groups: one received GE + GU 15 g/day, and the other GE + PL for 3 months and after that groups were crossed over. Guar gum and placebo were administered as granules taken 3 times a day during meals. Serum total cholesterol was 8.61 +/- 0.17 mmol/l before gemfibrozil therapy, and 7.29 +/- 0.15 mmol/l at the end of the run-in period on GE + PL (P less than 0.01). During the double-blind phase serum total cholesterol values were 6.28 +/- 0.19 mmol/l at the end of the GE + GU treatment period and 7.21 +/- 0.16 mmol/l at the end of the GE + PL treatment period (P less than 0.01). At the end of the GE + GU treatment period serum total cholesterol was 27% lower and LDL-cholesterol 39% lower than before gemfibrozil treatment. A marked improvement (23%) was found in HDL/LDL ratio during GE + GU treatment compared with GE + PL treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical aspect of HMG CoA reductase inhibitors

Subsequent to the discovery of compactin (ML-236B) as a specific inhibitor of HMG CoA reductase, a series of compactin analogs have been either isolated or synthesized. Several of these compounds, which include compactin, mevinolin (monacolin K) and CS-514, have been extensively studied. The inhibition of HMG CoA reductase by these compounds is reversible and competitive (Ki = approximately 1 nM). The 3', 5'-dihydroxypentanoic acid portion of the acid form of compactin analogs, which resembles the HMG portion of HMG CoA, plays a crucial role in inhibitory activity. These inhibitors block sterol synthesis both in cultured mammalian cells and in animals. Strong inhibition of sterol synthesis results in a marked increase in HMG CoA reductase activity both in vitro and in vivo. These compounds strongly lower plasma LDL-cholesterol levels in animals and humans. The lowering of LDL-cholesterol levels occurs by an inhibition of LDL synthesis and/or by an elevation of the receptor-mediated LDL catabolism in the liver.

Effects of CS-514 (eptastatin), an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, on serum lipid and apolipoprotein levels in heterozygous familial hypercholesterolemic patients treated by low density lipoprotein (LDL)-apheresis

Nine heterozygous patients with familial hypercholesterolemia (FH) were treated by low density lipoprotein (LDL)-apheresis using dextran sulfate cellulose columns. After more than 3 procedures of LDL-apheresis without drug therapy, combination therapy with LDL-apheresis and CS-514 (eptastatin), an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme (HMG-CoA) reductase, at a dose of 10 mg twice daily was started. Pre- and post-apheresis serum cholesterol levels were decreased significantly by CS-514, from 289 +/- 24 mg/dl (mean +/- SEM) to 247 +/- 25 mg/dl and from 118 +/- 7 mg/dl to 106 +/- 9 mg/dl, respectively. Pre- and post-apheresis apolipoprotein B levels decreased significantly on CS-514 from 160 +/- 9 mg/dl to 138 +/- 8 mg/dl and from 58 +/- 6 mg/dl to 45 +/- 6 mg/dl, respectively. No adverse effects were observed during the combination therapy. Thus, the addition of an inhibitor of HMG-CoA reductase to LDL-apheresis is a useful method for further reducing serum cholesterol and apolipoprotein B levels in FH heterozygotes.

Comparison of lovastatin and probucol in treatment of familial and non-familial hypercholesterolemia: different effects on lipoprotein profiles

In order to compare the effects of lovastatin and probucol on lipoprotein profiles, we treated 32 familial hypercholesterolemia (FH) heterozygotes and 26 patients with non-familial hypercholesterolemia for 14 weeks with either probucol (1 g/d) or lovastatin (40-80 mg/d) in a randomized double-blind study. Lovastatin at 80 mg/d reduced low density lipoprotein (LDL)-cholesterol and apo B by more than 40% in both familial and non-familial hypercholesterolemia (non-FH). Probucol reduced LDL-cholesterol by 10-17% while LDL-apo B levels were not influenced at all (FH) or fell by 13% (non-FH). Analysis of LDL composition demonstrated that the LDL-cholesterol lowering effect of probucol in FH was entirely due to reduction in the proportion of cholesterol in LDL with no reduction in LDL mass. Serum high density lipoprotein2 (HDL2)-cholesterol levels fell by 27-33% during probucol, whereas HDL2-cholesterol increased by 10-18% with lovastatin 80 mg/d. These changes in HDL2 were not mediated by lipoprotein lipase or hepatic lipase, both of which are known to participate in regulation of this lipoprotein.

Comparison between simvastatin and bezafibrate in effect on plasma lipoproteins and apolipoproteins in primary hypercholesterolaemia

The ability of simvastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, to lower lipid levels in 16 patients with primary hypercholesterolaemia was compared with that of bezafibrate in a 16-week, double-blind, parallel, placebo-controlled trial that was continued in an open crossover fashion. Simvastatin was better than bezafibrate at lowering total and low-density lipoprotein (LDL)-cholesterol and apolipoprotein B concentrations (30.4% [p less than 0.001], 37.3% [p less than 0.001], and 37.8% [p less than 0.001] vs 17.0%, 19.6%, and 24.0%, respectively). Both drugs increased the high-density lipoprotein (HDL)-cholesterol and apolipoprotein A-I, but this change was significant only with bezafibrate (p less than 0.05). Bezafibrate and simvastatin reduced triglycerides by 25.6% (p less than 0.001) and 13.7% (p less than 0.05), respectively. Very low-density lipoprotein (VLDL)-cholesterol was significantly reduced only by bezafibrate (44.3%, p less than 0.001). Both drugs were tolerated well and no serious side-effects were noted. The results show that simvastatin was more effective than bezafibrate in lowering total-cholesterol, LDL-cholesterol, and apolipoprotein B, while bezafibrate was better at lowering triglycerides and VLDL-cholesterol and at raising HDL-cholesterol and apolipoprotein A-I.

Simvastatin (MK-733): a potent cholesterol synthesis inhibitor in heterozygous familial hypercholesterolaemia

Simvastatin (MK-733), a new inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, was administered to 38 patients with heterozygous familial hypercholesterolaemia for 24 weeks. A dose of 40 mg per day produced a mean reduction in low density lipoprotein cholesterol of 43-45% and in triglycerides of 21-31%. Mean high density lipoprotein cholesterol increased significantly by 10-13%. There were no major differences in response whether the drug was taken in one or two doses. MK-733 was tolerated well. Adverse effects were infrequent and limited to slight increases of alanine aminotransferase, creatine phosphokinase and bilirubin. This drug appears to be a potent inhibitor of cholesterol synthesis and has produced the largest therapeutic response as monotherapy in patients with familial hypercholesterolaemia.

Lovastatin for lowering cholesterol levels in non-insulin-dependent diabetes mellitus

Coronary heart disease is an important cause of death in patients with non-insulin-dependent diabetes mellitus (NIDDM) and is particularly common in diabetic populations that have relatively high levels of plasma cholesterol. To determine whether plasma cholesterol levels in patients with NIDDM could be reduced by drug therapy, we assessed the effect of lovastatin, a potent inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, in a randomized double-blind placebo-controlled manner in 16 white patients with NIDDM and mild to moderate elevations of plasma cholesterol. Lovastatin (20 mg twice daily) or a placebo was given for four weeks, during which blood glucose concentrations remained controlled. As compared with the placebo, lovastatin reduced total cholesterol by 26 percent, low-density lipoprotein (LDL) cholesterol by 28 percent, and LDL apolipoprotein B by 26 percent. Lovastatin therapy also reduced plasma triglycerides and very-low-density lipoprotein cholesterol by 31 percent and 42 percent, respectively. Although there was no change in the plasma level of high-density lipoprotein (HDL) cholesterol, the ratio of total cholesterol to HDL cholesterol fell by 29 percent. No side effects or abnormalities in serum values were noted during short-term lovastatin therapy. The beneficial effects of lovastatin on plasma lipid levels in patients with NIDDM could decrease the risk of the development of coronary heart disease.

Hypercholesterolemia and atherosclerosis: present and future therapy including LDL-apheresis

Atherosclerosis-induced coronary heart disease remains the major cause of death and disability in industrialized countries. Hypercholesterolemia is recognized as a causative factor in the development of atherosclerosis. While the lowering of cholesterol levels as a treatment goal has met with general agreement and acceptance, the preferred methods for doing so are still open to conjecture. This literature review discusses various factors in the hypercholesterolemia-atherosclerosis link and surveys a variety of treatment protocols including diet modification, drug therapy, surgical intervention, and plasmapheresis. Evidence is accumulating to prove that the ideal hypercholesterolemia therapy is one that reduces LDL levels while maintaining or increasing HDL levels. Because LDL-apheresis has this potential, this paper also reviews the various LDL-apheresis methods, including immunoadsorption, chemical affinity, and double-membrane filtration.

Hypolipidemic effects of HMG-CoA reductase inhibitors in patients with hypercholesterolemia

Hypercholesterolemia with increased plasma concentrations of low density lipoproteins (LDL) is a major risk factor for the premature development of coronary atherosclerosis in humans and is best exemplified by patients with familial hypercholesterolemia. The recent development of several specific competitive inhibitors of the rate-limiting enzyme in cholesterol biosynthesis (3-hydroxy-3-methylglutaryl-coenzyme A reductase, HMG CoA reductase) has opened up an important new avenue of therapy for patients with hypercholesterolemia who are not responsive to dietary treatment alone. Three drugs, lovastatin (mevinolin), simvastatin (synvinolin) and pravastatin (CS 514), are currently undergoing clinical trials in North America and Europe; the former has recently been approved for general use. Experience with lovastatin and simvastatin in the treatment of patients with primary and secondary causes of hypercholesterolemia is reviewed. The relative potency of simvastatin appears to be greater than that of lovastatin and pravastatin but, with each drug, decreases in the plasma concentrations of LDL cholesterol of 30% to 50% can be achieved. The hypocholesterolemic effects of HMG CoA reductase inhibitors can be potentiated by combination therapy with other approved lipid-lowering medications including the bile acid sequestrants and nicotinic acid. If long-term safety can be satisfactorily established, specific inhibitors of HMG CoA reductase represent a major advance in the therapy of hypercholesterolemia and afford the potential to reduce substantially the high incidence of premature atherosclerosis that occurs in patients with persistent hypercholesterolemia.

Activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase does not respond to ubiquinone uptake in cultured cells

The cellular content of ubiquinone was increased approx. 10-fold by incubation of neuroblastoma cells in medium containing exogenous ubiquinone. Under these conditions the activity of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, assayed after preincubation of cell homogenates with or without fluoride, was not suppressed. Similar results were obtained with human skin fibroblast cultures to which free ubiquinone or low-density lipoprotein-ubiquinone complex had been added. Consistent with the lack of suppression of HMG-CoA reductase, the rate of incorporation of [1-14C] acetate into ubiquinone was not diminished in cells exposed to exogenous ubiquinone. Measurements of [3H]mevalonolactone incorporation into cellular ubiquinones indicated that exogenous ubiquinone did not affect ubiquinone synthesis at a point in the pathway distal to the formation of mevalonate. The results suggest that cultured mammalian cells lack an end-product 'feedback' mechanism for regulation of HMG-CoA reductase in response to ubiquinone uptake.

Effects of MK-733 on plasma lipid and lipoprotein levels in subjects with hypercholesterolaemia

MK-733, which is a competitive inhibitor of the rate-limiting step in cholesterol biosynthesis, or a matching placebo was administered to 30 subjects with primary hypercholesterolaemia (who were already receiving dietary treatment) over a period of four weeks in a double-blind trial. Twenty-one subjects manifested heterozygous familial hypercholesterolaemia and nine subjects had polygenic hypercholesterolaemia. Five subjects received placebo, 15 subjects a low dose of MK-733 (2.5-10 mg/day) and 10 subjects received a high dose of MK-733 (20-80 mg/day). Plasma cholesterol levels in subjects who were receiving MK-733 declined significantly and in a dose-dependent fashion (31% reduction in plasma cholesterol levels with a high dose, 19% reduction with a low dose). Eight of 10 subjects who were receiving a high dose of MK-733 achieved better than a 30% reduction in plasma cholesterol levels after four weeks of treatment. The response was independent of the presence or absence of familial hypercholesterolaemia. High-density lipoprotein cholesterol levels did not change significantly, but there was a suggestive, dose-dependent reduction in plasma triglyceride levels after four weeks of treatment. MK-733 was well-tolerated, appeared to be safe, and may ultimately become an important drug in the management of more severe grades of hypercholesterolaemia.

Effects of CS-514 on serum lipoprotein lipid and apolipoprotein levels in patients with familial hypercholesterolemia

Effects of CS-514, a new competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on serum lipoprotein lipid and apolipoprotein levels were studied in 13 heterozygous patients with familial hypercholesterolemia. Treatment with 10 mg of CS-514 twice daily reduced total serum cholesterol, low-density lipoprotein (LDL), and intermediate-density lipoprotein (IDL) cholesterol levels by 25%, 33%, and 33%, respectively, and increased high-density lipoprotein (HDL) cholesterol levels by 15%. Apolipoprotein B, E, and C-II levels decreased by 24%, 20%, and 19%, and apolipoproteins A-I and A-II levels increased by 10% and 7%, respectively. One patient showed abnormally high levels of SGOT, SGPT, and serum alkaline phosphatase, which returned to normal levels immediately after the cessation of CS-514. No other adverse effects were observed. Thus, CS-514 reduces atherogenic lipoproteins and apolipoprotein B, and increases HDL and apolipoprotein A-I and A-II, and appears to be a useful drug for heterozygous familial hypercholesterolemia.

Definition and management of hyperlipoproteinemia

The results of recent large, prospective clinical trials have established that the reduction of plasma total and low density lipoprotein cholesterol concentrations in certain hyperlipidemic patients reduced their risk for developing symptomatic cardiovascular disease. Attention has now been turned to both defining which individuals should be treated and how best to treat those patients. Utilizing the concepts of human lipid, lipoprotein, and apolipoprotein metabolism that have evolved over the past 20 years, the metabolism of the plasma lipoproteins can be effectively modulated in the majority of hyperlipoproteinemic patients. In addition to summarizing human lipoprotein metabolism, this article outlines a step-by-step approach to the treatment of hyperlipoproteinemia.

Effects of recombinant interferon-alpha 2 treatment upon lipid concentrations and lipoprotein composition

Interferon-alpha 2 (IFN-alpha 2) produced by recombinant DNA technology and purified to homogeneity, was assessed for effects on plasma lipids and lipoprotein composition in 10 patients with metastatic malignant melanoma. Patients received 30 X 10(6) U/m2 IFN intravenously for 5 consecutive days every 3 weeks. Plasma cholesterol concentrations were significantly decreased after 3 days of IFN administration (171 +/- 37 mg/dl, mean +/- SD) when compared with pretreatment concentrations (211 +/- 28 mg/dl, p less than 0.05). Approximately 34% of the decrease in plasma cholesterol concentration was contributed by high-density lipoprotein (HDL). Significant decreases in plasma HDL cholesterol (44 +/- 8 to 34 +/- 7 mg/dl, p less than 0.05) and apolipoprotein A-1 concentrations (124 +/- 14 to 95 +/- 17 mg/dl, p less than 0.05) occurred. Although decreases in low-density lipoprotein (LDL) cholesterol concentrations contributed to the majority of the total decrease observed in plasma cholesterol, IFN did not alter the cholesterol-to-protein ratio of the LDL. When IFN-alpha 2 was discontinued, alterations in plasma lipoproteins returned to pretreatment levels. Plasma triglyceride concentrations were not influenced by IFN treatment nor did administration of IFN decrease very-low-density lipoprotein (VLDL). The overall effect of recombinant (r) IFN-alpha 2 on lipid composition was to reduce LDL and HDL without alteration of VLDL or triglycerides.

Mevinolin, an inhibitor of cholesterol synthesis, induces mRNA for low density lipoprotein receptor in livers of hamsters and rabbits

Through the use of a quantitative solution hybridization assay with 32P-labeled cDNA probes, we found that mevinolin, an inhibitor of cholesterol synthesis, elevates the level of mRNA for the low density lipoprotein receptor in livers of hamsters and rabbits. In hamsters the maximal effect (3-fold increase) occurred at 0.1% mevinolin in the diet for 10 days. The same dose produced a maximal induction (10-fold) of mRNA levels for 3-hydroxy-3-methylglutaryl CoA reductase, the rate-limiting enzyme of cholesterol synthesis, and a maximal decrease (80%) in plasma cholesterol. The drug lowered the level of all cholesterol-carrying lipoproteins in plasma. In normal rabbits, mevinolin produced a 90% reduction in plasma low density lipoprotein-cholesterol levels, which was associated with a 2.5-fold increase in low density lipoprotein receptor mRNA levels. A similar induction of receptor mRNA occurred in livers of Watanabe-heritable hyperlipidemic rabbits, although the plasma cholesterol was not reduced to normal, presumably because the receptors produced by the mutant mRNA function poorly. These data are consistent with the hypothesis that mevinolin and other inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase lower plasma cholesterol levels in part by stimulating production of mRNA for the low density lipoprotein receptor in liver.

Effects of synvinolin (MK-733) on plasma lipids in familial hypercholesterolaemia

The effects of synvinolin (MK-733), a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, were investigated in 43 patients with heterozygous familial hypercholesterolaemia in a double-blind, placebo-controlled, dose-finding study. Synvinolin was given in doses ranging from 2.5 mg to 80 mg per day for 4 weeks. 8 patients received placebo. Low-density-lipoprotein cholesterol fell on average by 18% on 2.5 mg/day and 42% on 80 mg/day. The drug was as effective whether it was given once or twice daily. Serum high-density-lipoprotein cholesterol tended to increase and serum triglycerides to decrease on the higher doses. The drug was tolerated well. Except for a slight rise in alanine aminotransferase in 3 patients no objective side-effects were observed.

Combined treatment with cholestyramine and nicotinic acid in heterozygous familial hypercholesterolaemia: effects on biliary lipid composition

In ten patients with heterozygous familial hypercholesterolaemia, combination therapy with cholestyramine and nicotinic acid was instituted for a minimum of 2 months. During therapy, plasma low-density lipoprotein levels were reduced by 32%, and low-density lipoprotein to high-density lipoprotein ratios by 40%. The cholesterol saturation of fasting gall-bladder bile was reduced by 33% during treatment. We conclude that long-term combination therapy with cholestyramine and nicotinic acid is practically feasible in heterozygous familial hypercholesterolaemia, normalizes plasma cholesterol and low-density lipoprotein levels in many patients, and does not result in unwanted side-effects on biliary lipids. It should therefore be considered as the therapy of choice in this condition.

Treatment of homozygous patients with familial hypercholesterolemia by double-filtration plasmapheresis

Two homozygous patients with familial hypercholesterolemia were treated by double-filtration plasmapheresis. The plasma separated by the first filter was subsequently led to the second filter of ethylene vinylalcohol co-polymer hollow fibers, which trap very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) preferentially to other plasma constituents. Serum, VLDL, IDL, LDL cholesterol levels decreased by 55, 68, 59 and 55%, respectively. HDL cholesterol levels decreased by 39%. Immunoglobulins and fibrinogen levels decreased significantly. Cutaneous and tendinous xanthomas became smaller. off

The effect of CS-514, an inhibitor of HMG-CoA reductase, on serum lipids in healthy volunteers

CS-514 is a competitive inhibitor of HMG-CoA reductase. The effect of this agent on serum lipids and lipoproteins was studied in 10 healthy normocholesterolemic male volunteers by giving 20 mg of CS-514 or placebo twice a day for 7 days under double-blind conditions. The mean total serum cholesterol level decreased by 18.6% in the CS-514 group, whereas it increased by 7.4% in the placebo group and the difference between the two groups was statistically significant (P less than 0.01). LDL cholesterol and LDL apo B values were reduced by 22.6% and 23.2%, respectively. Serum triglyceride level did not change significantly. No clinical or laboratory abnormalities were observed.

Effectiveness of mevinolin on plasma lipoprotein concentrations in type II hyperlipoproteinemia

Patients with low-density lipoprotein (LDL) concentrations in the top 10th percentile of the population (type II hyperlipoproteinemia [HLP]) are at increased risk for premature cardiovascular disease; however, the incidence of myocardial infarction and death can be decreased by LDL cholesterol reduction. Mevinolin, an inhibitor of endogenous cholesterol synthesis, has been shown to reduce LDL cholesterol concentrations in a subset of type II patients with heterozygous familial hypercholesterolemia (FH). Using a double-blind, randomized, crossover, placebo-controlled trial, the safety and efficacy of mevinolin were compared in 24 patients with type II HLP with heterozygous FH (n = 6) or without FH type II HLP (n = 18). Compared with placebo treatment, both apolipoprotein B and LDL cholesterol levels were reduced (p less than 0.01) in both FH and non-FH patients by 28 to 34% with mevinolin treatment. In addition, high-density lipoprotein cholesterol levels were significantly increased (p less than 0.001) in both patients with FH (16%) and those with non-FH type II HLP (14%). Patients had no serious or clinically significant adverse effects. Thus, mevinolin is a useful drug for treatment of most patients with elevated plasma LDL cholesterol concentrations.

Inhibition of cholesterol synthesis by ketoconazole

To determine if ketoconazole influences cholesterol metabolism in humans, plasma lipid levels were studied in seven men with advanced prostate cancer who were being treated with high-dose ketoconazole. Additionally, the effects of ketoconazole on cholesterol synthesis in cultured normal human fibroblasts were studied. High-dose ketoconazole therapy caused a 27 percent reduction in total serum cholesterol values without affecting serum triglyceride levels. The reduction in serum cholesterol levels was maintained for five months in six of seven patients. The fall in total cholesterol levels was due to a 38 percent reduction in low-density lipoprotein cholesterol levels without associated changes in high-density lipoprotein cholesterol levels. Serum lanosterol levels increased 46 percent during ketoconazole treatment. Studies in cultured normal human fibroblasts showed that ketoconazole inhibited cholesterol synthesis by blocking the conversion of lanosterol to cholesterol. These results establish that ketoconazole is a potent inhibitor of cholesterol production in vivo and in vitro.

Suppression of murine neuroblastoma growth in vivo by mevinolin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase catalyzes the formation of mevalonate, an essential precursor for isoprenoid compounds in mammalian cells. Recent studies have shown that mevinolin, a competitive inhibitor of the reductase, inhibits cell proliferation and induces differentiation in cultured C1300 (Neuro-2A) murine neuroblastoma cells. We now report that mevinolin can inhibit neuroblastoma growth in vivo. The specific activity of HMG-CoA reductase in subcutaneous neuroblastomas increased more than 20-fold between the fifth and eighth days after tumor inoculation, and remained elevated for the remainder of the tumor lifetime in mice. The increase in reductase activity was correlated with a marked increase in tumor DNA content and exponential increase in tumor weight. Using an in vitro assay to monitor the ability of mouse serum to suppress sterol synthesis, we determined that mevinolin was inactivated or cleared from the circulation within 3-6 h after a single subcutaneous injection. However, by using subcutaneous osmotic pumps to deliver a constant infusion of mevinolin, we were able to maintain adequate blood levels of the drug for 7 d. Mevinolin (5 mg/kg per h) suppressed tumor growth (wet weight) significantly when treatment was carried out between day 1 and day 8 or between day 5 and day 12 after tumor inoculation. Histopathological examination of tumors from mevinolin-treated mice revealed few or no mitotic figures and marked cellular degeneration. Measurements of incorporation of (3H)acetate into neuroblastoma sterols and ubiquinones 24 h after implantation of osmotic pumps showed that mevinolin produced a marked inhibition of isoprenoid synthesis in the tumors in vivo. The data suggest that, in addition to their demonstrated utility as cholesterol-lowering drugs, competitive inhibitors of HMG-CoA reductase may have considerable potential as novel antineoplastic agents.

The influence of mevinolin on the adrenal cortical response to corticotropin in heterozygous familial hypercholesterolemia

The biosynthesis of adrenal corticosteroids in humans depends on a continuous supply of cholesterol, which can be derived from both local synthesis and receptor-mediated uptake of low density lipoproteins (LDL) from plasma. Mevinolin, an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase [mevalonate:NAD+ oxidoreductase (CoA-acylating), EC 1.1.1.88] is an effective hypolipidemic agent in patients with heterozygous familial hypercholesterolemia. To determine whether mevinolin influences the adrenal production of corticosteroids, the adrenocortical response to a continuous 36-hr infusion of corticotropin (ACTH) was examined in eight patients with heterozygous familial hypercholesterolemia before, and again during, treatment with mevinolin (40-80 mg/day). The drug produced an average decrease of 28% and 34% in the plasma concentrations of total and LDL cholesterol. Serum cortisol levels showed similar increases in response to ACTH stimulation before and during mevinolin treatment, and the rates of excretion of urine-free cortisol were also similar. We conclude that clinically effective doses of mevinolin do not affect corticosteroid production by the adrenal cortex during prolonged ACTH stimulation in patients with heterozygous familial hypercholesterolemia.

Xanthomas and hyperlipidemias

The ability to recognize diverse clinical forms of xanthomas, such as tuberous, planar, eruptive and tendinous, is important in the detection of underlying systemic disease. A variety of primary genetic disorders, as well as numerous secondary conditions such as diabetes, obstructive liver disease, thyroid disease, renal disease, and pancreatitis, can lead to hyperlipoproteinemia that results in the formation not only of xanthomas but also of life-threatening vascular atherosclerosis. An understanding of the pathogenesis of the underlying lipoprotein alterations provides a rational approach to therapy utilizing dietary manipulations and drugs. Such treatment is capable of correcting most disorders of lipid metabolism, and, if appropriate therapy is initiated at the first sign of xanthoma evolution, it may prevent progression of atherosclerosis, provide resolution of xanthomas, and in some instances prevent serious pancreatitis.