Ciprofibrate in the therapy of type II hypercholesterolemia. A double-blind trial

Efficacy and safety of high-density lipoprotein cholesterol-increasing compounds: a meta-analysis of randomized controlled trials

OBJECTIVES

The aim of this research was to estimate the efficacy and safety of current high-density lipoprotein cholesterol (HDL-C)-increasing drugs.

BACKGROUND

Epidemiologic evidence has shown that HDL-C is inversely related to coronary heart disease (CHD) risk. However, the evidence for reducing CHD risk by raising HDL-C is thin, predominantly due to the paucity of effective and safe HDL-increasing drugs.

METHODS

Randomized controlled trials with fibrates and niacin, published between 1966 through February 2004 (MEDLINE), were retrieved. Information on treatment, baseline characteristics, serum lipids, end points, and side-effects were independently abstracted by two authors using a standardized protocol.

RESULTS

Data from 53 trials (16,802 subjects) using fibrates and 30 trials (4,749 subjects) using niacin were included. Random-effects model showed 11% versus 10% reduction in total cholesterol, 36% versus 20% reduction in triglycerides, 8% versus 14% reduction in low-density lipoprotein cholesterol, and 10% versus 16% increase in HDL-C for fibrates and niacin, respectively. Apart from flushes in the niacin group, both fibrates and niacin were shown to be well-tolerated and safe. Fibrates reduced the risk for major coronary events by 25% (95% confidence interval 10% to 38%), whereas current available data for niacin indicate a 27% reduction.

CONCLUSIONS

Fibrates reduce major coronary events and increase HDL-C levels without significant toxicity. Niacin has a more potent effect on HDL-C levels, whereas data on cardiovascular event rate reduction are limited. Future studies need to evaluate whether additional HDL increase by fibrates or particularly newer niacin formulations on top of statin therapy translates into further event reduction in high-risk subjects, without significant toxicity.

Fibrate-induced increase in blood urea and creatinine: is gemfibrozil the only innocuous agent?

BACKGROUND

Some reports indicate that fibrates can induce renal dysfunction. However, the clinical characteristics of these episodes, and the respective nephrotoxicity of the four main fibrates used-namely, fenofibrate, bezafibrate, ciprofibrate, and gemfibrozil-remain ill defined.

METHODS

To better characterize this side-effect, we first reviewed the charts of 27 patients from our institution who developed an impairment of renal function during fibrate therapy. We next analysed the articles (n=24) that contained data on renal function in patients taking fibrates (n=2676).

RESULTS

Among our 27 patients, 25 were on fenofibrate therapy, one was taking bezafibrate, and one ciprofibrate. Nineteen were recipients of solid-organ transplants (kidney recipients, n=15; heart or heart-lung recipients, n=4), and eight were non-transplanted patients with some impairment of renal function. Baseline plasma creatinine ranged from 0.9 to 2.9 mg/dl. It increased by a mean of 40% after the start of fibrate therapy. There was a concomitant increase of blood urea values (mean 36%) in most of the patients. Renal function returned to baseline in 18/24 patients after fibrate discontinuation. However, six patients, all transplant recipients, experienced a permanent increase in plasma creatinine. The incidence of fibrate-induced renal dysfunction among our series of kidney transplant recipients was 60%, as it occurred in 15 of the 25 patients who had ever taken fibrates. An increase of mean creatinine values during therapy was described in all papers on fenofibrate (n=7) and bezafibrate (n=8) (range 8-18% and 8-40% respectively), and in three of four papers dealing with ciprofibrate (range 6-16%). No significant renal impairment was described in any of the eight articles reporting data on gemfibrozil therapy.

CONCLUSION

Therapy with fenofibrate, bezafibrate, and ciprofibrate may induce renal dysfunction. Gemfibrozil appears to be devoid of this side-effect.

Comparative efficacy and safety of ciprofibrate and sustained-release bezafibrate in patients with type II hyperlipidaemia

The hypolipidaemic efficacy and safety of ciprofibrate were compared with a sustained-release formulation of bezafibrate (Bezalip Mono) in 174 patients with type II hyperlipidaemia. This multicenter, open, parallel-group study was conducted in general practice. A total of 83 patients received 100 mg ciprofibrate once daily and 91 received 400 mg bezafibrate once daily for eight weeks. Concentrations of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides were measured at baseline (after stabilisation on a lipid-lowering diet) and after eight weeks. Safety was assessed from reports of adverse events and by measuring haematological and biochemical parameters. After eight weeks, ciprofibrate produced a significantly greater decrease in total cholesterol (-17.8% vs -12.5%), low-density lipoprotein cholesterol (-22.4% vs -17.2%), and triglycerides (-33.9% vs -26.1%). High-density lipoprotein cholesterol concentrations were increased significantly by both drugs (19.6% with ciprofibrate, 24.9% with bezafibrate) but the differences between drugs were non-significant. Both drugs were well tolerated, with headache the most widely reported adverse event.

Novel lipid-lowering properties of Vaccinium myrtillus L. leaves, a traditional antidiabetic treatment, in several models of rat dyslipidaemia: a comparison with ciprofibrate

Vaccinium myrtillus L. (blueberry) leaf infusions are traditionally used as a folk medicine treatment of diabetes. To further define this therapeutical action, a dried hydroalcoholic extract of the leaf was administered orally to streptozotocin-diabetic rats for 4 days. Plasma glucose levels were consistently found to drop by about 26% at two different stages of diabetes. Unexpectedly, plasma triglyceride (TG) were also decreased by 39% following treatment. Subsequent to the latter observation, possible lipid-lowering properties of the extract were investigated on other models of hyperlipidaemia and ciprofibrate, a well-established hypolipidaemic drug, was used as a reference compound. Both drug reduced TG levels of rats on hyperlipidaemic diet in a dose-dependent fashion. When administered at single doses over the same experimental period, blueberry and ciprofibrate were effective in lowering TG concentrations in ethanol-treated normolipidaemic animals and in genetically hyperlipidaemic Yoshida rats. Unlike ciprofibrate, however, blueberry failed to prevent the rise in plasma TG elicited by fructose and did not affect free fatty acid levels in any of the above experimental conditions. In rats treated with Triton WR-1339, blueberry feeding induced an hypolipidaemic activity one hour after injection but proved to be ineffective at later time points, thus suggesting that its hypolipidaemic action may reflect improved TG-rich lipoprotein catabolism. In addition, ciprofibrate and the extract were tested for antithrombotic activity using a collagen-triggered model of venous thrombosis in diabetic and Yoshida rats. Only ciprofibrate, however, significantly reduced thrombus formation in diabetics, possibly because of its effects on free fatty acid metabolism, whereas no effect was observed in Yoshida rats. In conclusion, the present findings indicate that active consituent(s) of Vaccinium myrtillus L. leaves may prove potentially useful for treatment of dyslipidaemiae associated with impaired TG-rich lipoprotein clearance.

Ciprofibrate versus gemfibrozil in the treatment of primary hyperlipidaemia

The efficacy and short-term safety of ciprofibrate and gemfibrozil were compared in a 12-week, double-blind, randomised study. One-hundred-and-ten primary, type II hyperlipidaemic patients were randomised to receive either ciprofibrate, 100 mg/day once daily, or gemfibrozil, 1200 mg/day twice daily. Treatment efficacy was measured by complete lipid and lipoprotein profiles and by plasma fibrinogen levels. Tolerability was assessed by drug compliance and safety was evaluated by laboratory safety parameters, physical examination and evaluation of adverse events. Mean reductions of plasma TC and low density lipoprotein cholesterol levels were similar in the two treatment groups. In contrast, the mean relative reduction of plasma total triglyceride and very low density lipoprotein triglyceride levels was significantly higher in patients receiving gemfibrozil as compared with ciprofibrate (P < 0.05). The absolute reduction of the last two parameters was higher in the ciprofibrate group compared with the gemfibrozil group; furthermore, the mean concentrations of these parameters were within normal limits at the end of the study. The clinical relevance of the statistically significant difference mentioned should, therefore, be questioned. Ciprofibrate therapy significantly reduced (-8.33%) and gemfibrozil therapy significantly increased (+6.97%) plasma fibrinogen levels (P < 0.001 compared with baseline in each case). Adverse events were rare, mild and equally distributed between the two treatment groups. Laboratory safety parameters did not show any significant changes. Ciprofibrate and gemfibrozil have comparable short-term efficacy and safety profiles. Furthermore, ciprofibrate reduces fibrinogen levels and benefits from a once daily regimen.

Efficacy and safety of ciprofibrate in hyperlipoproteinaemias

Ciprofibrate is an effective treatment for three main types of atherogenic hyperlipoproteinaemia: type IIa hypercholesterolaemia, type IIb combined hyperlipidaemia, and type IV hypertriglyceridaemia. In type IIa hypercholesterolaemia, administration of 100 mg/day of ciprofibrate, to approximately 3000 patients, decreased total cholesterol (TC), triglycerides, apolipoprotein B (apo B) and low-density lipoprotein (LDL) cholesterol. Levels of apolipoproteins in high-density lipoprotein (HDL) cholesterol and apolipoprotein AI (apo A-I) were increased. Administration of the same dose of ciprofibrate, to approximately 3500 patients with type IIb combined hyperlipidaemia, had a marked cholesterol- and triglyceride-lowering effect, in addition to producing a decrease in LDL cholesterol and apo B, and an increase in apo A-I. TC levels were also decreased in type IV hypertriglyceridaemia following administration of 100 mg/day of ciprofibrate to 800 patients. The decrease in TC levels was attributable to a decrease in triglyceride levels and an increase in HDL cholesterol levels. The pharmacokinetics, mechanism of action and safety of ciprofibrate treatment are also discussed.

The effects of fibrates on lipoprotein and hemostatic coronary risk factors

The effects of fibrates on lipoprotein profiles and lipoprotein physiology, as well as on selected coagulation and fibrinolytic factors are reviewed. It is concluded that the action of fibrates on these systems is such as to render the fibrates beneficial in atherosclerosis prevention.

Effects of ciprofibrate on LDL metabolism in man

This study examined the effects of ciprofibrate therapy (100 mg/day) on plasma lipids, lipoproteins and low density lipoprotein (LDL) kinetic heterogeneity in moderately hypercholesterolaemic subjects. The drug lowered plasma triglyceride and cholesterol by 41% and 17%, respectively. Very low density lipoprotein (VLDL) cholesterol fell by 38%, LDL cholesterol fell by 22%, while the content of the lipid in high density lipoprotein (HDL) increased by 11%. LDL structural and metabolic heterogeneity were assessed before and during therapy in eight subjects. Density gradient centrifugation was used to fractionate LDL into three species. LDL-I, the least dense, was not affected by therapy whereas LDL-II and LDL-III were decreased by 28% (P < 0.01) and 31% (N.S.). Baseline turnover studies revealed that LDL catabolism was subnormal and this was the cause of the raised cholesterol in these subjects. Ciprofibrate therapy increased the apoLDL fractional catabolic rate (FCR) by 19%, principally by inducing a 38% enhancement (P < 0.03) in apoLDL removal by the receptor pathway. ApoLDL kinetics exhibited metabolic heterogeneity both before and during drug therapy. Analysis of plasma decay curves for the LDL tracer and urinary excretion data indicated that the lipoprotein comprised two metabolically distinct species, one with an FCR of about 0.50 pools/day (Pool A), the other with an FCR of about 0.18 pools/day (Pool B). Drug therapy decreased synthesis of and hence reduced the plasma mass of apoLDL in the slow metabolised pool B. This perturbation in synthesis was linked to the change in plasma triglyceride concentration. The resultant reduced proportion of pool B vs. pool A material accounted for the observed promotion of LDL receptor-mediated clearance. Ciprofibrate, therefore, produced beneficial changes in the plasma levels of VLDL, LDL and HDL and in the metabolism of LDL.

Ciprofibrate therapy normalises the atherogenic low-density lipoprotein subspecies profile in combined hyperlipidemia

The effect of ciprofibrate treatment on the atherogenic profile of low-density lipoprotein (LDL) subspecies in combined hyperlipidemia (CHL) has been investigated in six patients displaying elevated plasma triglyceride and cholesterol levels (> 200 and > 250 mg/dl, respectively). The E2E2 phenotype was excluded; four patients possessed familial antecedents of premature coronary heart disease (CHD). Analysis of five LDL subclasses separated by isopycnic density gradient ultracentrifugation showed a predominance of dense LDL subspecies (LDL-4 and LDL-5, d 1.039-1.063 g/ml; 51% of total LDL mass) in the asymmetric LDL density profile characteristic of CHL patients at baseline. Ciprofibrate treatment (100 mg/day for 1 month) effected marked reductions in both total plasma LDL and apo B-100 levels (approximately 19% and approximately 23%, respectively). Equally, the plasma profile of LDL subspecies was normalised to a significant degree as a result of preferential reduction in the elevated levels of both dense subspecies (LDL-4 and LDL-5; -43% and -54%, respectively; P < 0.03 and P < 0.006 [corrected], respectively). The circulating concentrations of light LDL (LDL-1, d 1.019-1.023 g/ml) were also diminished significantly by ciprofibrate (-30%; P < 0.006 [corrected]). Furthermore, ciprofibrate not only effected reductions in the elevated triglyceride content of the hydrophobic core of all LDL subspecies but also normalised their common deficiency in free cholesterol. In addition, the abnormally small particle diameters of LDL-4 and -5 were increased to normal. Plasma levels of both apo B-100 and triglycerides were significantly and positively correlated with those of LDL-4 and LDL-5, suggesting not only that the degree of triglyceride elevation is intimately linked to the extent of shift in LDL subclass profile towards denser subspecies, but also that triglyceride reduction upon treatment strongly influences LDL-4 and LDL-5. In conclusion, our findings indicate that ciprofibrate treatment in combined hyperlipidemia results in marked reduction in plasma triglyceride levels (-33%), and that such reduction is intimately linked to normalisation of both the qualitative and quantitative features of the atherogenic LDL subspecies profile typical of this disorder.

The comparative pharmacokinetics and gastric toxicity of bezafibrate and ciprofibrate in the rat

1. The comparative gastric toxicology and pharmacokinetics of two phenoxyisobutyrate derivatives have been evaluated in the Fischer rat. 2. After oral administration of single daily doses for 7 days, the plasma elimination half-life for bezafibrate was rapid (t1/2 of 4-5 h) in comparison to ciprofibrate (t1/2 of 76 h). 3. The area under the plasma drug concentration versus time curve (AUC) 0-24 (micrograms.h/ml +/- SD) for bezafibrate (dose 125 mg/kg per day) was 1553 +/- 334, which was less than half the value of 3748 +/- 358 achieved by ciprofibrate (10 mg/kg per day) after 7 days. 4. Oral administration of ciprofibrate at 10 mg/kg every 48 h produced similar sustained plasma concentrations to those achieved by bezafibrate 125 mg/kg dosed every 12 h. The AUC 0-48 values (micrograms.h/ml +/- SD) achieved were 5124 +/- 450 for bezafibrate compared to 4207 +/- 240 for ciprofibrate. 5. In chronic oral multidose studies with ciprofibrate and bezafibrate, similar gastric toxicity (neuroendocrine cell hyperplasia) occurred in the rat when dose regimens were adjusted to compensate for the pharmacokinetic differences between these two drugs.

Effects of ciprofibrate and fenofibrate on liver lipids and lipoprotein synthesis in normo- and hyperlipidemic rats

The plasma lipoprotein and liver lipid composition, and the lipid, cholesterol and apolipoprotein synthesis have been studied in normal and diet-induced hyperlipidemic rats, receiving ciprofibrate (2.5 mg/kg body weight) or fenofibrate (50 mg/kg b.w.) for 8 days. Ciprofibrate is about 25-fold more active than fenofibrate in reducing plasma triglyceride and cholesterol concentrations both in normolipemic and in hyperlipemic rats. In normolipemic rats ciprofibrate reduced the concentration and the lipid content of all lipoprotein classes. The incorporation of [14C]palmitate and [3H]leucine into the lipoproteins was reduced by ciprofibrate and fenofibrate. The reduction in lipoprotein production was confirmed by prevention of Triton-induced hyperlipemia. Liver and plasma cholesterol synthesis estimated by 3H2O and [14C]mevalonate incorporation indicated an inhibitory effect on HMG-CoA reductase. Administration of ciprofibrate or fenofibrate to rats fed a fat and cholesterol-rich diet partially prevented liver steatosis and hyperlipemia. Both drugs reduced the overproduction of lower density lipoproteins. The ratio of (VLDL + LDL)-cholesterol/HDL-cholesterol which was increased by the diet alone from 0.4 (normal) to 11 remained close to the normal value in the animals receiving ciprofibrate. In the hyperlipemic animals, ciprofibrate reduced the incorporation of [3H]oleate into the liver and plasma glycerolipid and increased cholesterol esterification. Ciprofibrate efficiently reduces plasma levels of cholesterol, triglyceride and phospholipid. Cholesterol and glycerolipid synthesis in the liver were significantly reduced leading to a lower lipoprotein secretion rate in both normolipidemic and diet-induced hyperlipidemic rats.

Assessment of gastric antisecretory effects of phenoxyisobutyrate derivatives in the rat and the mouse

After the observation of a low incidence of gastric carcinoid tumours in rats, but not in mice, given ciprofibrate for 2 years, ciprofibrate and related compounds were investigated for gastric antisecretory activity. A significant inhibition of gastric secretion, similar to that induced by comparable doses of cimetidine, was observed in the fischer rat 1.5 h after a single oral (200 or 500 mg kg-1) or intraduodenal (100 or 300 mg kg-1) administration of ciprofibrate, bezafibrate, and clofibric acid. Ciprofibrate had prolonged antisecretory activity when compared with bezafibrate or ranitidine. Prolonged inhibition of gastric secretion is proposed as the primary cause of gastric carcinoids in the rat, since in a comparative evaluation, antisecretory activity was observed in the rat but not in the mouse.

The effect of ciprofibrate on gastric secretion in the rat

The potential of ciprofibrate to inhibit gastric secretion has been investigated in the rat. A significant gastric antisecretory effect was observed following a single oral administration of 300 and 500 mg kg-1 and following a single intraduodenal dose of 100, 300 and 500 mg kg-1. The toxicological significance of this finding is discussed in the light of a spate of recent publications linking changes in gastric morphology with hypergastrinaemia produced as a secondary effect of inhibition of acid secretion.

An overview of lipid-lowering drugs

The long term use of lipid-lowering drugs in the treatment of patients with hyperlipoproteinaemia is aimed at reducing plasma concentrations of known atherogenic lipoproteins with a favourable effect on lipid deposition in the arterial wall. A less common aim is to prevent the adverse sequelae of hyperchylomicronaemia in patients with severe hypertriglyceridaemia. The decision to begin drug therapy should be made only after the exclusion of secondary factors and after an adequate trial of diet has failed to produce acceptable concentrations of plasma lipids and lipoproteins. The bile acid sequestrants (cholestyramine and colestipol), nicotinic acid, fenofibrate and inhibitors of hydroxymethylglutaryl coenzyme A (HMG CoA) reductase (e.g. lovastatin or simvastatin) are the most effective drugs for use in patients with primary hypercholesterolaemia; these agents reduce plasma concentrations of total and LDL-cholesterol by 15 to 45%. For those patients with concurrent hypertriglyceridaemia, nicotinic acid, lovastatin or simvastatin, or fenofibrate are the preferred drugs for initial use; bile acid sequestrants frequently exacerbate hypertriglyceridaemia in these patients. Fibric acid derivatives (e.g. clofibrate, gemfibrozil, bezafibrate or fenofibrate) are all effective in the therapy of patients with type III hyperlipoproteinaemia, as is nicotinic acid and I have found lovastatin to be effective also. Gemfibrozil or nicotinic acid are the most effective agents to use in the treatment of patients with severe hypertriglyceridaemia who are at increased risk of abdominal pain and pancreatitis. Combined therapy with drugs which have different mechanisms of action can be effectively used in the treatment of patients with severe hypercholesterolaemia or combined hyperlipidaemia; for the former group, combinations which use bile acid sequestrants, HMG CoA reductase inhibitors and nicotinic acid are the most effective.

Current pharmacologic treatment of elevated serum cholesterol

A basic difference between dietary and drug therapy of hypercholesterolemia is that dietary therapy can be used as part of a population strategy, whereas the decision to use drugs is always made on an individual basis. In each case, the decision to treat must be based on the assumption that more good than harm is caused to the patient. This is a difficult situation for the physician. As long as there is no easy way of assessing the state and rate of progression of coronary lesions, the physician must treat the patient on statistical grounds only, i.e., rely on the results of studies showing that lowering serum cholesterol significantly decreases the risk of coronary events. Such evidence has recently been strengthened, which increases motivation for both physician and patients. The current general opinion is that drug therapy must be generally confined to those at high risk, i.e., patients with severe hypercholesterolemia. For individuals with moderately elevated serum cholesterol levels, dietary advice and correction of other risk factors should be adequate.

Characterization of ciprofibrate and clofibric acid as peroxisomal proliferators in primary cultures of rat hepatocytes

We have determined the comparative activities of peroxisomal proliferators, ciprofibrate and clofibric acid on various hepatic parameters associated with endoplasmic reticulum, mitochondria and peroxisomes in primary cultures of rat hepatocytes. We have measured the activities of carnitine acetyltransferase and fatty acylCoA oxidase, and the amount of 60 and 80 kD polypeptides as biochemical markers of the peroxisomal function; laurate hydroxylase and cytochrome P-450 as markers of the endoplasmic reticulum; and carnitine palmitoyltransferase as a marker of mitochondria in primary cultures of hepatocytes. Ciprofibrate (0.01 to 0.3 mM) and clofibric acid (0.1 to 3 mM) produced similar changes in several components of cultured hepatocytes within 72 hr. Increases of protein (18 and 11%), carnitine palmitoyltransferase (23 and 97%), cytochrome P-450 (37 and 49%), carnitine acetyltransferase (484 and 614%), fatty acylCoA oxidase (529 and 931%) and laurate hydroxylase (624 and 671%) were obtained in hepatocytes after a 72-hr exposure to 0.1 mM ciprofibrate and 1.0 mM clofibric acid, respectively. In cultured hepatocytes, ciprofibrate was about 30-fold more active than clofibric acid for the stimulation of carnitine acetyltransferase, laurate hydroxylase and fatty acylCoA oxidase activities. Ciprofibrate was also more potent than clofibric acid as an inducer of the 60 and 80 kD proteins in hepatocytes. The maximal drug-induced increases in carnitine acetyltransferase activity were not additive, and the induction of carnitine acetyltransferase by ciprofibrate was blocked by addition (1 micrograms per ml) of cycloheximide or actinomycin D. Changes in protein and RNA synthesis preceded the drug-induced increases of carnitine acetyltransferase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Irreversible inhibition of hepatic glutathione S-transferase by ciprofibrate, a peroxisome proliferator

Ciprofibrate (2-[4-(2,2-dichlorocyclopropyl) phenoxy]2-methyl propionic acid) which is a hypolipidemic agent and has been shown to cause peroxisome proliferation, non-competitively inhibits glutathione S-transferase activity of rat liver, both in vivo and in vitro. Among all the glutathione S-transferases of rat liver, ligandin is maximally inhibited by ciprofibrate. Studies with the purified glutathione S-transferases of rat liver indicate that the affinities of different subunits of liver enzymes for ciprofibrate are in the order Ya greater than Yb, Yb' greater than Yc.