Clinical implications of new drugs for lowering plasma cholesterol concentrations

Synthesis and biological activity of 4,5-polymethylenepyrazole-derived HMG-COA reductase inhibitors

New HMG-CoA reductase inhibitors, in which 3-substituted 4,5-polymethylenepyrazoles are employed as a hydrophobic anchor connected to tetrahydro-4-hydroxy-2H-pyran-2-one by a two-carbon bridge, were designed and synthesized to exhibit significant inhibitory activity comparable to mevinolin. The most potent enzyme inhibitor (11cc, IC(50)=0.01 muM) is 4-fold more potent than lovastatin.

Cerivastatin in the treatment of mixed hyperlipidemia: the RIGHT study. The Cerivastatin Study Group. Cerivastatin Gemfibrozil Hyperlipidemia Treatment

The Cerivastatin Gemfibrozil Hyperlipidemia Treatment (RIGHT) study--a multicenter, randomized, double-blind, placebo-controlled study--compared the lipid-lowering effects of cerivastatin, once daily at doses of 0.1, 0.2, and 0.3 mg with those of twice-daily gemfibrozil 600 mg in 751 patients with primary mixed hyperlipidemia. Randomization to the first 16 weeks of treatment followed an initial 4-week washout period and subsequent 6-week diet-controlled, placebo run-in phase. Patients continued to receive study medication for a further 36 weeks, with those previously on placebo switched to 0.1 mg/day cerivastatin at the end of week 16. Additional cholestyramine therapy was permitted at week 36 in patients with uncontrolled low-density lipoprotein (LDL) cholesterol levels. Cerivastatin achieved significant dose-dependent reductions in LDL cholesterol of 15-24% after 16 weeks of treatment, compared with reductions of 7.5% with gemfibrozil. Over this period both cerivastatin (0.3 mg) and gemfibrozil (1,200 mg) significantly decreased levels of triglycerides (20.3% vs 50.3%, respectively) and very low-density lipoprotein (VLDL) cholesterol (30.8% vs 47.1%, respectively), as well as increasing high-density lipoprotein (HDL) cholesterol (11.3% vs 13.3%, respectively). The reductions in LDL cholesterol and other atherogenic lipids and lipoproteins at 16 weeks were sustained in the subsequent 36-week double-blind continuation phase, during which time <10% of patients received additional cholestyramine therapy. Both study drugs were well tolerated, with the incidence of adverse events similar to that of placebo treatment. Clinically significant increases in hepatic transaminases and creatine phosphokinase occurred at a similar low frequency of around 1%. This study demonstrated that cerivastatin is a safe, well-tolerated, and effective treatment for lowering elevated LDL cholesterol and triglycerides in patients with mixed hyperlipidemia.

Comparison of the efficacy and safety of fenofibrate and lovastatin in patients with primary type IIa or IIb hyperlipidaemia

OBJECTIVES

To evaluate and compare the efficacy and safety of fenofibrate and lovastatin in patients with type IIa or IIb hyperlipidaemia.

METHODS

One hundred patients entered this single-centre, open, comparative trial. After 2 months of diet therapy, 33 patients (16 with type IIa and 17 with type IIb hyperlipidaemia) were randomized to treatment for 3 months with a single daily 300 mg dose of fenofibrate or 20 mg of lovastatin.

RESULTS

After 3 months of drug therapy, fenofibrate and lovastatin produced significant reductions in levels of total cholesterol and low-density lipoprotein cholesterol in type IIa hyperlipidaemia. In type IIb, the levels of total cholesterol were significantly decreased by both drugs, but only lovastatin significantly reduced low-density lipoprotein cholesterol in these patients. High-density lipoprotein cholesterol levels were significantly increased by lovastatin in type IIa and fenofibrate in type IIb. Fenofibrate decreased total triglyceride levels in both types of hyperlipidaemia significantly more effectively than lovastatin. The most important and commonly observed adverse effects in the fenofibrate group were dermatological events (three patients), myalgia (two patients) and asymptomatic increase in aminotransferase values (nine patients), while in the lovastatin group cardiovascular events (five patients) were the most common. All five patients had coronary heart disease at baseline. In general terms, both drugs were well tolerated.

CONCLUSIONS

Comparison between fenofibrate and lovastatin after 3 months of drug therapy in both types IIa and IIb hyperlipidaemia demonstrated that both drugs produced similar reductions in levels of total cholesterol and low-density lipoprotein cholesterol. However, fenofibrate decreased total triglyceride levels in both types of hyperlipidaemia, more effectively than lovastatin. Thus, fenofibrate is suitable for both primary hypercholesterolaemia and combined hyperlipidaemia.

Pravastatin. A reappraisal of its pharmacological properties and clinical effectiveness in the management of coronary heart disease

Pravastatin is an HMG-CoA reductase inhibitor which lowers plasma cholesterol levels by inhibiting de novo cholesterol synthesis. Pravastatin produces consistent dose-dependent reductions in both total and low density lipoprotein (LDL)-cholesterol levels in patients with primary hypercholesterolaemia. Favourable changes in other parameters such as total triglyceride and high density lipoprotein (HDL)-cholesterol levels are generally modest. Combination therapy with other antihyperlipidaemic agents such as cholestyramine further enhances the efficacy of pravastatin in patients with severe dyslipidaemias. Available data suggest that pravastatin is effective in elderly patients and in patients with hypercholesterolaemia secondary to diabetes mellitus or renal disease. The benefit of cholesterol-lowering in terms of patient outcomes is currently an area of considerable interest. Recently completed regression studies (PLAC I, PLAC II, KAPS and REGRESS) show that pravastatin slows progression of atherosclerosis and lowers the incidence of coronary events in patients with mild to moderately severe hypercholesterolaemia and known coronary heart disease. Large scale primary (WOSCOPS) and secondary (CARE) prevention studies, moreover, demonstrate that pravastatin has beneficial effects on coronary morbidity and mortality. In WOSCOPS, all-cause mortality was reduced by 22%. Pravastatin is generally well tolerated by most patients (including the elderly), as evidenced by data from studies of up to 5 years in duration. As with other HMG-CoA reductase inhibitors, myopathy occurs rarely (< 0.1% of patients treated with pravastatin): approximately 1 to 2% of patients may present with raised serum levels of hepatic transaminases. Thus, with its favourable effects on cardiovascular morbidity/mortality and total mortality, pravastatin should be considered a first-line agent in patients with elevated cholesterol levels, multiple risk factors or coronary heart disease who are at high risk of cardiovascular morbidity.

First-pass elimination of a peptidomimetic thrombin inhibitor is due to carrier-mediated uptake by the liver. Interaction with bile acid transport systems

CRC 220 (4-methoxy-2, 3, 6-trimethylphenylsulfonyl-L-aspartyl-D-4-amidinophenylalanyl -piperidide) is a competitive peptide-based trombin inhibitor with high affinity to human alpha-thrombin (Ki 2.5 nM). The amphiphilic compound exhibits virtually no systemic bioavailability despite proteolytic stability and proven enteral absorption. After intravenous application (V. jejunalis) in rats CRC 220 is almost completely excreted into bile. Simultaneous administration of bile acids considerably decreases this first-pass elimination. CRC 220 is extensively taken up in isolated rat hepatocytes by a saturable carrier-mediated transport with Km 23.7 microM and Vmax 775 pmol x mg-1 x min-1. A large part of this transport is energy-dependent. At temperatures above 20 degrees C, the uptake is accelerated exponentially. The activation energy amounts to 82 kj/mol. A minor portion of CRC 220 uptake occurs by physical diffusion with a permeability coefficient of 7.83 x 10(-7) cm/sec at 12 degrees C. Sodium ions energize CRC 220 uptake. Replacement of sodium by choline or lithium decreases the transport rate of 23-40%. In addition, a negative membrane potential facilitates the uptake. CRC 220 transport is only observed in hepatocytes: it is absent in BHK, FAO, HepG2, HPCT 1E3, and HPCT 1E3-TC cells. In the presence of 4-amidinophenylalanine derivatives, CRC 220 uptake is considerably decreased. Inhibition also occurs with bile acids and bromosulfophthalein, but less with bumetanide. Because CRC 220 inhibits bile acid uptake into hepatocytes and vice versa, the results suggest that the first-pass elimination of this amphiphilic thrombin inhibitor is due to an active carrier-mediated transport process in the basolateral plasma membrane of rat hepatocytes, and that this transport occurs via a bile acid transport system.

Design, rational, and baseline characteristics of the Prospective Pravastatin Pooling (PPP) project--a combined analysis of three large-scale randomized trials: Long-term Intervention with Pravastatin in Ischemic Disease (LIPID), Cholesterol and Recurrent Events (CARE), and West of Scotland Coronary Prevention Study (WOSCOPS)

The Prospective Pravastatin Pooling (PPP) project is a pooled evaluation of 3 large, placebo-controlled, randomized trials of cholesterol-lowering treatment with pravastatin. It is designed to more reliably evaluate the effect of treatment on coronary and all-cause mortality and on total coronary artery disease (CAD) events for specific populations of interest, including women and the elderly. The trials--Long-Term Intervention With Pravastatin in Ischemic Disease trial, the Cholesterol and Recurrent Events trial, and the West of Scotland Coronary Prevention Study--each have common design features, including drug, dose, and duration. The project prospectively defines the objectives, end points, and analytic plans in a protocol developed before results are known of any individual trial. More than 2,000 (or 10%) of the participants in the pooled data set are women, 1,841 are aged > or = 70 years at trial entry, and > 6,000 have a total cholesterol < 5.5 mmol/L (213 mg/dl). The mean low-density lipoprotein cholesterol level is 4.2 mmol/L (162 mg/dl). The mean blood pressure level is 134/81 mm Hg and 20% are current smokers. Half of the PPP participants have had a prior myocardial infarction. More than 7% have a history of diabetes and 26% have a history of hypertension. PPP is projected to have data on about 1,100 CAD deaths, 500 non-CAD deaths, and > 1,000 cancers by study completion.(ABSTRACT TRUNCATED AT 250 WORDS)

Simvastatin. A reappraisal of its pharmacology and therapeutic efficacy in hypercholesterolaemia

Simvastatin is an HMG-CoA reductase inhibitor used in the treatment of patients with hypercholesterolaemia. Since the time simvastatin was previously reviewed in Drugs, a number of large clinical trials have confirmed its clinical efficacy. Thus, reductions from baseline were approximately 20 to 40% for serum levels of total cholesterol, 35 to 45% for low density lipoprotein (LDL)-cholesterol and 10 to 20% for triglycerides in patients with primary hypercholesterolaemia receiving simvastatin 10 to 40 mg/day. High density lipoprotein (HDL)-cholesterol levels were increased modestly by about 5 to 15%. Recent data from long term studies indicate that little or no attenuation of these changes in serum lipid and lipoprotein levels occurred with administration of simvastatin for 3 to 5.4 years. Comparative studies with other HMG-CoA reductase inhibitors (lovastatin, pravastatin and fluvastatin), which were lacking at the time of the previous review of simvastatin, demonstrated greater reductions in serum levels of total cholesterol and LDL-cholesterol with simvastatin than equal dosages of lovastatin or pravastatin. Reductions in serum levels of total cholesterol and LDL-cholesterol were similar between agents only when lovastatin or pravastatin were administered at a total daily dosage twice that of simvastatin and when fluvastatin was administered at a total daily dosage approximately 8 times that of simvastatin. In general, simvastatin 10 to 40 mg/day was also more effective than standard dosages of bile acid sequestrants, fibrates or probucol in lowering serum levels of total cholesterol and LDL-cholesterol; however, fibrates usually produced greater reductions in serum triglycerides and greater elevations in HDL-cholesterol levels. The Scandinavian Simvastatin Survival Study (4S), a large secondary prevention study in patients with coronary heart disease and concomitant hypercholesterolaemia, demonstrated that simvastatin 20 to 40 mg/day for a median of 5.4 years significantly reduced overall mortality (the primary end-point of the study) by 30% compared with placebo, which was attributed to a 42% relative reduction in coronary mortality. Coronary morbidity was also significantly reduced by simvastatin in the 4S trial. The tolerability profile of simvastatin appears to be comparable to that of other HMG-CoA reductase inhibitors. The most frequently reported adverse events are gastrointestinal disturbances, which are generally mild and tend to occur less frequently than with cholestyramine. In conclusion, simvastatin is among the most effective agents available for treating patients with hypercholesterolaemia.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacokinetics of the combination of fluvastatin and gemfibrozil

High-risk patients with dyslipidemias resistant to diet and single-agent pharmacotherapy may require combination therapy to achieve target levels of low density lipoprotein, triglycerides, and high density lipoprotein. Combinations of fibrates and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors are effective, but because of safety concerns related to myopathy and rhabdomyolysis, it is important to consider the possibility of pharmacokinetic interactions when such combinations are used. In this study, the area under the curve, maximum plasma concentration, and time to maximum concentration for fluvastatin and gemfibrozil are compared, when used alone and in combination, in patients with hyperlipidemia and either coronary or carotid atherosclerosis, or a family history of coronary artery disease. A total of 17 patients were studied in a random sequence, open-label, crossover study of fluvastatin at 20 mg twice daily, gemfibrozil at 600 mg twice daily, and the combination of the 2 drugs. No significant difference was observed in area under the curve, maximum plasma concentration, and time to maximum concentration when comparing the combination with each drug alone. These pharmacokinetic data add support to the clinical observations that the combination of fluvastatin and gemfibrozil is both effective and safe.

Gastrointestinal absorption of pravastatin in healthy subjects

The bioavailability of pravastatin, a hypocholesterolmic agent, may be enhanced by decreasing its exposure to stomach contents, where it may be converted nonenzymatically to a relatively inactive metabolite. The pharmacokinetics of pravastatin and its metabolite were determined after infusion of pravastatin directly into the stomach (locus for greatest bioavailability for the metabolite), duodenum (greatest bioavailability for pravastatin), jejunum, or ileum. An enterically coated formulation of pravastatin may increase its bioavailability.

Hepatoselective carrier-mediated sodium-independent uptake of pravastatin and pravastatin-lactone

Pravastatin and pravastatin-lactone are not taken up into extrahepatic cells such as fibroblasts, or hepatoma cells such as AS-30D ascites hepatoma cells or FAO cells. In contrast, pravastatin is taken up into isolated rat hepatocytes by a carrier mediated, saturable, temperature-dependent and energy-dependent mechanism. The kinetic parameters for the saturable uptake are Km 27 microM, Vmax 537 pmol/mg per min. The permeability coefficients were determined to be 9.829 x 10(-7) cm/s at 4 degrees C, 1.76 x 10(-6) cm/s at 7 degrees C, 3.85 x 10(-6) cm/s at 17 degrees C and 5.82 x 10(-6) cm/s at 37 degrees C. The activation energy is 60 kJ/mol for 100 microM pravastatin at 37 degrees C. The Q10 values are between 1.7 and 2.8. In the presence of metabolic inhibitors and in the absence of oxygen, transport is inhibited. Uptake of pravastatin is not dependent on an extracellular to intracellular sodium-gradient. Replacement of chloride by sulfate, nitrate, gluconate or thiocyanate significantly inhibits the uptake of pravastatin. Uptake is competitively inhibited by cholate and taurocholate in the presence and absence of sodium. Pravastatin, however, competitively inhibits the uptake of cholate and taurocholate only in the absence of sodium. In addition, pravastatin-lactone enters liver cells via an energy-dependent, carrier-mediated uptake system. For the saturable energy-dependent part of the hepatocellular uptake a Km value of 9 microM and a Vmax value of 621 pmol/mg per min was determined. The permeability coefficient of pravastatin-lactone uptake is calculated to be 5.41 x 10(-6) cm/s at 37 degrees C. The uptake of pravastatin-lactone is competitively-noncompetitively inhibited by pravastatin and by lovastatin and vice versa. These results indicate that the hepatoselectivity of pravastatin is due to its carrier-mediated uptake into rat hepatocytes via a sodium-independent bile acid carrier. Pravastatin-lactone resembles pravastatin-sodium in its hepatoselectivity.

Simvastatin therapy for hypercholesterolemic patients with nephrotic syndrome or significant proteinuria

Experimental evidence suggests that lipid lowering therapy could slow the progression of renal disease in humans. We have conducted a double-blind, placebo controlled trial of the HMG CoA reductase inhibitor simvastatin in patients with the nephrotic syndrome or significant proteinuria (> 1 g/day) and hypercholesterolemia (> or = 6.5 mmol/liter). Patients were placed on a lipid lowering diet for at least 10 weeks before randomization. After a four-week placebo run-in, 30 adults were randomized to simvastatin or placebo therapy (10 mg/day, increasing to 20 to 40 mg/day as required) for 24 weeks. There were seven dropouts, none of whom were "definitely" related to drug therapy. Total and LDL cholesterol levels fell by a mean of 33 and 31%, respectively, in simvastatin treated patients, compared with only 5 and 1% in patients on placebo (P < 0.001, P = 0.002, respectively). Apolipoprotein B100 levels fell by a mean of 31% in the simvastatin group but rose 0.3% in the placebo group (P = 0.014). There were no significant changes in HDL levels. There were no significant differences between the groups in their urine protein levels, their rise in plasma creatinine, or decline in plasma inulin clearance. Simvastatin is a safe, effective therapy for hypercholesterolemia in proteinuric states. A much larger trial is needed to show if potent lipid-lowering therapy slows progression of hypercholesterolemic proteinuric diseases.

Efficacy and tolerability of simvastatin and pravastatin in patients with primary hypercholesterolemia (multicountry comparative study). The European Study Group

A total of 291 patients with primary hypercholesterolemia [total plasma cholesterol > or = 6.20 mmol/liter (> or = 240 mg/dl)] were enrolled in an open, randomized, parallel, comparative study of simvstatin and pravastatin. All patients started or continued a standard lipid-lowering diet for > or = 6 weeks before entry into the 4-week placebo baseline period. There were 145 patients who received simvastatin and 146 patients who received pravastatin, both at the commonly recommended starting dose of 10 mg once daily, for a treatment period of 6 weeks. Concentrations of total cholesterol in plasma were reduced by 23% with simvastatin, and by 16% with pravastatin. Concentrations of low-density lipoprotein cholesterol in plasma were reduced by 32 and 22%, and high-density lipoprotein cholesterol concentrations were increased by 7 and 5% with simvastatin and pravastatin, respectively. Plasma triglyceride concentrations were reduced by 13% with simvastatin and by 6% with pravastatin. Adverse experiences were similar between treatment groups and both drugs were well tolerated. In each treatment group, 3 patients were withdrawn from the study for clinical adverse experiences; 1 patient in the pravastatin group required a reduction in dose to 5 mg/day because of insomnia. At the commonly recommended starting dose for each, simvastatin had a significantly greater lipid-lowering effect than pravastatin. Both drugs were well tolerated.