Treatment with hydroxymethylglutaryl-coenzyme A reductase inhibitors in hypercholesterolemia induces changes in the components of the extrinsic coagulation system

How it all starts: Initiation of the clotting cascade

The plasma coagulation system in mammalian blood consists of a cascade of enzyme activation events in which serine proteases activate the proteins (proenzymes and procofactors) in the next step of the cascade via limited proteolysis. The ultimate outcome is the polymerization of fibrin and the activation of platelets, leading to a blood clot. This process is protective, as it prevents excessive blood loss following injury (normal hemostasis). Unfortunately, the blood clotting system can also lead to unwanted blood clots inside blood vessels (pathologic thrombosis), which is a leading cause of disability and death in the developed world. There are two main mechanisms for triggering the blood clotting, termed the tissue factor pathway and the contact pathway. Only one of these pathways (the tissue factor pathway) functions in normal hemostasis. Both pathways, however, are thought to contribute to thrombosis. An emerging concept is that the contact pathway functions in host pathogen defenses. This review focuses on how the initiation phase of the blood clotting cascade is regulated in both pathways, with a discussion of the contributions of these pathways to hemostasis versus thrombosis.

D-dimer: An Overview of Hemostasis and Fibrinolysis, Assays, and Clinical Applications

D-dimer is the smallest fibrinolysis-specific degradation product found in the circulation. The origins, assays, and clinical use of D-dimer will be addressed. Hemostasis (platelet and vascular function, coagulation, fibrinolysis, hemostasis) is briefly reviewed. D-dimer assays are reviewed. The D-dimer is very sensitive to intravascular thrombus and may be markedly elevated in disseminated intravascular coagulation, acute aortic dissection, and pulmonary embolus. Because of its exquisite sensitivity, negative tests are useful in the exclusion venous thromboembolism. Elevations occur in normal pregnancy, rising two- to fourfold by delivery. D-dimer also rises with age, limiting its use in those >80 years old. There is a variable rise in D-dimer in active malignancy and indicates increased thrombosis risk in active disease. Elevated D-dimer following anticoagulation for a thrombotic event indicates increased risk of recurrent thrombosis. These and other issues are addressed.

The role of tissue factor pathway inhibitor in atherosclerosis and arterial thrombosis

Tissue factor pathway inhibitor (TFPI) is the main inhibitor of tissue factor (TF)-mediated coagulation. In atherosclerotic plaques TFPI co-localizes with TF, where it is believed to play an important role in attenuating TF activity. Findings in animal models such as TFPI knockout models and gene transfer models are consistent on the role of TFPI in arterial thrombosis as they reveal an active role for TFPI in attenuating arterial thrombus formation. In addition, ample experimental evidence exists indicating that TFPI has inhibitory effects on both smooth muscle cell migration and proliferation, both which are recognized as important pathological features in atherosclerosis development. Nonetheless, the clinical relevance of these antithrombotic and atheroprotective effects remains unclear. Paradoxically, the majority of clinical studies find increased instead of decreased TFPI antigen and activity levels in atherothrombotic disease, particularly in atherosclerosis and coronary artery disease (CAD). Increased TFPI levels in cardiovascular disease might result from complex interactions with established cardiovascular risk factors, such as hypercholesterolemia, diabetes and smoking. Moreover, it is postulated that increased TFPI levels reflect either the amount of endothelial perturbation and platelet activation, or a compensatory mechanism for the increased procoagulant state observed in cardiovascular disease. In all, the prognostic value of plasma TFPI in cardiovascular disease remains to be established. The current review focuses on TFPI in clinical studies of asymptomatic and symptomatic atherosclerosis, coronary artery disease and ischemic stroke, and discusses potential atheroprotective actions of TFPI.

Tissue factor pathway inhibitor: structure-function

TFPI is a multivalent, Kunitz-type proteinase inhibitor, which, due to alternative mRNA splicing, is transcribed in three isoforms: TFPIalpha, TFPIdelta, and glycosyl phosphatidyl inositol (GPI)-anchored TFPIbeta. The microvascular endothelium is thought to be the principal source of TFPI and TFPIalpha is the predominant isoform expressed in humans. TFPIalpha, apparently attached to the surface of the endothelium in an indirect GPI-anchor-dependent fashion, represents the greatest in vivo reservoir of TFPI. The Kunitz-2 domain of TFPI is responsible for factor Xa inhibition and the Kunitz-1 domain is responsible for factor Xa-dependent inhibition of the factor VIIa/tissue factor catalytic complex. The anticoagulant activity of TFPI in one-stage coagulation assays is due mainly to its inhibition of factor Xa through a process that is enhanced by protein S and dependent upon the Kunitz-3 and carboxyterminal domains of full-length TFPIalpha. Carboxyterminal truncated forms of TFPI as well as TFPIalpha in plasma, however, inhibit factor VIIa/tissue factor in two-stage assay systems. Studies in gene-disrupted mice demonstrate the physiological importance of TFPI.

Increased tissue factor pathway inhibitor activity is associated with myocardial infarction in young women: results from the RATIO study

BACKGROUND

The tissue factor pathway inhibitor (TFPI)/protein S anticoagulant system is a potent inhibitor of blood coagulation. TFPI and protein S are major determinants of thrombin generation (TG) tests determined at low tissue factor (TF) and at high TF concentrations in the presence of activated protein C (APC). Both TFPI and protein S protect against venous thrombosis, but the importance of the TFPI/protein S system in arterial thrombosis remains unclear.

OBJECTIVES

To investigate the influence of the TFPI/protein S anticoagulant system on the risk of myocardial infarction (MI) in young women.

METHODS

The RATIO study is a case-control study in women under 50 years of age, including 205 patients and 638 controls. TFPI and protein S were quantified using ELISA. The TFPI/protein S activity (nTFPIr) and the APC sensitivity ratio (nAPCsr) were determined using TG tests. Odds ratios (ORs) adjusted for putative confounders and corresponding 95% confidence intervals (95% CI) were determined.

RESULTS

Women with MI had higher TFPI levels than controls (135.9 ± 40% vs. 124.2 ± 41%), resulting in increased TFPI/protein S activities and increased APC sensitivity. Furthermore, an increased TFPI activity was associated with MI [nTFPIr: adjusted OR Q1 vs. Q4 = 2.1 (95%CI 1.1-4.1)]. Additionally, an increased APC sensitivity was associated with MI [nAPCsr: adjusted OR Q1 vs. Q4 = 1.7 (95% CI 0.9-3.2)]

CONCLUSION

Women with MI had increased TFPI levels compared with controls. Consequently, the TFPI/protein S activity and APC sensitivity are increased in women with MI. Whether this increase in TFPI activity acts as a compensating mechanism for an increased procoagulant state or is a marker of endothelial damage remains to be investigated.

Support of drug therapy using functional foods and dietary supplements: focus on statin therapy

Functional foods and dietary supplements might have a role in supporting drug therapy. These products may (1) have an additive effect to the effect that a drug has in reducing risk factors associated with certain conditions, (2) contribute to improve risk factors associated with the condition, other than the risk factor that the drug is dealing with, or (3) reduce drug-associated side effects, for example, by restoring depleted compounds or by reducing the necessary dose of the drug. Possible advantages compared with a multidrug therapy are lower drug costs, fewer side effects and increased adherence. In the present review we have focused on the support of statin therapy using functional foods or dietary supplements containing plant sterols and/or stanols, soluble dietary fibre, n-3 PUFA or coenzyme Q10. We conclude that there is substantial evidence that adding plant sterols and/or stanols to statin therapy further reduces total and LDL-cholesterol by roughly 6 and 10 %, respectively. Adding n-3 PUFA to statin therapy leads to a significant reduction in plasma TAG of at least 15 %. Data are insufficient and not conclusive to recommend the use of soluble fibre or coenzyme Q10 in patients on statin therapy and more randomised controlled trials towards these combinations are warranted. Aside from the possible beneficial effects from functional foods or dietary supplements on drug therapy, it is important to examine possible (negative) effects from the combination in the long term, for example, in post-marketing surveillance studies. Moreover, it is important to monitor whether the functional foods and dietary supplements are taken in the recommended amounts to induce significant effects.

Altered hemostatic balance and endothelial activation in pregnant women with familial hypercholesterolemia

INTRODUCTION

Patients with familial hypercholesterolemia (FH) are prone to premature cardiovascular disease. During pregnancy plasma lipids reach higher absolute values in FH than in healthy women. Pregnancy is associated with activation of coagulation and possibly also of vascular endothelium, which might further increase the risk of cardiovascular disease in FH. However, whether hemostatic and endothelial activation markers are increased in pregnant FH women compared with non-FH pregnancies, is unknown.

MATERIALS AND METHODS

Activation markers of hemostasis and endothelium were analyzed in blood samples collected prospectively from 22 heterozygous FH women during pregnancy and compared with those of a reference group of 149 healthy, pregnant women.

RESULTS

A procoagulant pattern was detected in both groups, but was more evident among FH women at least partly due to their enhanced thrombin generation, and because tissue factor pathway inhibitor type 1 increased in the reference group only. Furthermore, plasminogen activator inhibitor type 2 antigen increased more in FH than in the reference group. Whereas C-reactive protein, intercellular adhesion marker-1 and E-selectin did not change appreciably, vascular endothelial cell adhesion molecule 1 rose markedly in FH.

CONCLUSION

Increased lipid levels as well as a net procoagulant activity and an enhanced endothelial activation possibly confer additional risks of cardiovascular disease among pregnant FH women.

Differential modulation by simvastatin of the metabolic pathways in the n-9, n-6 and n-3 fatty acid series, in human monocytic and hepatocytic cell lines

Statins affect the production of long chain polyunsaturated fatty acids (PUFA), both in vitro and in vivo. Various studies have shown the effects of statins on the pattern of n-6 fatty acids (FA), but limited attention has been paid to the n-3 FA. We investigated, in THP-1 and in HepG2 cells, the effects of simvastatin on the conversion of the 18C FA precursors in the n-3 and n-6 series, [1-(14)C] alpha-linolenic acid (alpha-LNA) and [1-(14)C] linoleic acid (LA) respectively, and on the metabolism of [1-(14)C] stearic acid (SA). THP-1 cells, as in the case of LA, actively converted alpha-LNA to its products, and after simvastatin treatment, the total conversion was significantly increased (from 57.2+/-7.2 to 74.3+/-8.5%, p<0.05). HepG2 cells also converted LA and alpha-LNA, but simvastatin increased significantly only the conversion of LA (9.5+/-1.9% versus 23.8+/-5.1%, p<0.02). SA conversion was similar in untreated cells (about 50%), while statin increased the production of oleic acid in HepG2, but in THP-1 cells there was a decrease. In conclusion, LA, alpha-LNA and SA are differentially metabolized in THP-1 and in HepG2 cells and their increased conversion by simvastatin is lower in HepG2 than in THP-1. These differences may reflect the distinct features of the two cell lines: monocytes, precursors of phagocytic cells, versus hepatocytes with mainly metabolic functions. Substantial differences concern also cellular FA pools: structural in THP-1 cells, and also depot, resulting in sequestering of the substrates, in HepG2. The greater n-3 FA metabolism in THP-1 cells may have favourable functional effects.

Differential effects of estrogens and progestins on the anticoagulant tissue factor pathway inhibitor in the rat

Oral contraceptives (OC) and postmenopausal hormone therapy (HT) modulate plasma levels of proteins that regulate blood coagulation. It remains unclear whether the progestin component contributes to these changes. The present study was designed to determine whether progestins modulate two essential plasma anticoagulants, antithrombin (AT) and tissue factor pathway inhibitor (TFPI), in an animal model. Ovariectomized rats were treated orally with three progestins, norethindrone acetate (NETA), trimegestone (TMG), or drospirenone (DSP), either alone or combined with 17alpha-ethyinylestradiol (EE). Plasma AT levels were unchanged. However, TFPI activity was reduced by EE alone (10-100 microg/kg/day) in a dose-dependent manner; NETA (3 or 10 mg/kg/day) reduced TFPI by approximately 40 or approximately 80%, respectively, while TMG and DSP had no effect. NETA and EE effects were blocked by co-administration of ICI-182,780, an estrogen receptor antagonist, suggesting that both responses were likely estrogen receptor-mediated. Reduced TFPI after NETA or EE treatment was not accompanied by changes in TFPI mRNA levels in tissues that express TFPI, but there was a positive correlation between plasma TFPI and total cholesterol. Sex hormone effects on TFPI in this model and as reported in women may help to shift the coagulation balance to a more prothrombotic state. Progestins such as TMG and DSP that lack estrogenic activity could potentially have an improved clinical profile.

Effects of Addition of Policosanol to??Omega-3 Fatty Acid Therapy on the??Lipid Profile of Patients with Type??II Hypercholesterolaemia

BACKGROUND

Policosanol is a mixture of higher aliphatic primary alcohols purified from sugar-cane wax. The mixture has cholesterol-lowering efficacy, its specific effects being to reduce serum total (TC) and low-density lipoprotein cholesterol (LDL-C), and to increase high-density lipoprotein cholesterol (HDL-C). The effects of policosanol on triglycerides (TG) are modest and inconsistent. Omega-3 fatty acids (FA) from fish oil protect against coronary disease, mainly through antiarrhythmic and antiplatelet effects. Omega-3 FA also have lipid-modifying effects, mostly relating to TG reduction. Thus, potential benefits could be expected from combined therapy with omega-3 FA and policosanol.

OBJECTIVE

To investigate whether combined therapy with omega-3 FA + policosanol offers benefits compared with omega-3 FA + placebo with respect to the lipid profile of patients with type II hypercholesterolaemia.

METHODS

This randomised, double-blind study was conducted in 90 patients with type II hypercholesterolaemia. After 5 weeks on a cholesterol-lowering diet, patients were randomised to omega-3 FA + placebo, omega-3 FA + policosanol 5 mg/day or omega-3 FA + policosanol 10 mg/day for 8 weeks. Omega-3 FA was supplied as 1g capsules (two per day); placebo and policosanol were provided in tablet form. Physical signs and laboratory markers were assessed at baseline and after 4 and 8 weeks on therapy. Drug compliance and adverse experiences (AEs) were assessed at weeks 4 and 8. The primary efficacy variable was LDL-C reduction; other lipid profile markers were secondary variables.

RESULTS

After 8 weeks, omega-3 FA + policosanol 5 and 10 mg/day, but not omega-3 FA + placebo, significantly reduced LDL-C by 21.1% and 24.4%, respectively (both p < 0.0001). Omega-3 FA + policosanol 5 mg/day also significantly lowered TC (12.7%; p < 0.01) and TG (13.6%; p < 0.05), and significantly increased HDL-C (+14.4%; p < 0.001). Omega-3 FA + policosanol 10 mg/day significantly decreased TC (15.3%; p < 0.001) and TG (14.7%; p < 0.01), and significantly increased HDL-C (+15.5%; p < 0.0001). Omega-3 FA + placebo significantly reduced TG (14.2%; p < 0.05) but had no significant effect on other lipid profile variables. The proportion of randomised patients in the omega-3 FA + policosanol 5 or 10 mg/day groups that achieved LDL-C targets or reductions 15% was significantly greater than in the omega-3 FA + placebo group (p < 0.001). Combined therapy with omega-3 FA + policosanol 5 or 10 mg/day resulted in significantly greater changes in LDL-C, TC and HDL-C than treatment with omega-3 FA + placebo, but did not modify the TG response compared with the omega-3 FA + placebo group. Four patients (two in the omega-3 FA + placebo group and two in the omega-3 FA + policosanol 10 mg/day group) withdrew from the study; none of these withdrawals was due to AEs. Two patients reported mild AEs, namely nausea/headache (one in the omega-3 FA + placebo group) and heartburn (one in the omega-3 FA + policosanol 5 mg/day group).

CONCLUSIONS

Policosanol 5 or 10 mg/day administered concomitantly with omega-3 FA 1 g/day improved LDL-C, TC and HDL-C, maintained the reduction in TG attributable to omega-3 FA monotherapy, and was well tolerated. Treatment with omega-3 FA + policosanol could be useful for regulating lipid profile in patients with type II hypercholesterolaemia, but further studies involving larger sample sizes are needed before definitive conclusions can be drawn.

Optimal management of hyperlipidemia in primary prevention of cardiovascular disease

Cardiovascular disease (CVD) in the developed countries continues to grow at an epidemic proportion. There are a significant number of young adults with no clinical evidence of CVD, but who have two or more risk factors that predispose them to CV events and death. Many of these risk factors are modifiable, and by controlling these factors, the CVD burden can be decreased significantly. Recent statistics have shown that, if all major forms of CVD were eliminated, the life expectancy would rise by almost 7 years. Hence it is imperative that primary prevention efforts should be initiated at a young age to avert decades of unattended risk factors. Hyperlipidemia has been linked to CVD almost a century ago. Since then various clinical trials have not only supported this link, but have also shown the CV benefits in aggressively treating patients with hyperlipidemia. In this generation, we have various therapeutic agents that are capable of reducing the elevated lipid levels. With drugs like statins, we are able to reduce the risk of CVD by about 30% and avoid major adverse events. Newer drugs are being researched and introduced in the treatment of hyperlipidemia in humans. These can be used in combination therapy resulting in optimal levels of lipids. The new National Cholesterol Education Program (NCEP)/Adult Treatment Panel III (ATP III) guidelines have come as a wake-up call to clinicians about primary prevention of CVD through strict lipid management and multifaceted risk management approach in the prevention of CVD.

Dyslipidemia, statins, and venous thromboembolism: a potential risk factor and a potential treatment

The optimal drug for the prevention of venous thromboembolism is one that is efficacious, associated with minimal bleeding risk, and easy to administer. Statins fulfill the latter two criteria, but their efficacy remains unproved. By examining the association between dyslipidemia and venous thromboembolism, as well as the evidence that statins might prevent venous thromboembolism, there may be a new rationale for the use of this class of drugs. There may be a common link between arterial and venous thrombosis. Dyslipidemia may be one of the many systemic factors associated not only with arterial thrombosis, but with venous thromboembolism as well. This may occur through the effects of circulating lipid molecules on the vascular endothelium, platelet function, and coagulation factors. By impeding these mechanisms, statins may be protective against venous thrombosis, but epidemiologic studies are few in number, and no randomized clinical trials have been conducted. Better epidemiologic evidence is required to establish whether dyslipidemia is a risk factor for venous thromboembolism. If future observational studies can demonstrate that statins are associated with a lower risk of venous thromboembolism, then consideration should be given to conducting a randomized clinical trial comparing statins with placebo for the prevention of venous thromboembolism. Until then, the efficacy of statins for the prevention or treatment of venous thromboembolism remains uncertain.

Effect of long-term hormone replacement therapy on tissue factor pathway inhibitor and thrombin activatable fibrinolysis inhibitor in healthy postmenopausal women: a randomized controlled study

It was recently reported from the Women's Health Initiative that healthy women using combined hormone replacement therapy (HRT) for 5 years have an increased cardiovascular risk. We hypothesize that the increased risk is confined to subgroups of atherosclerotic women. Such women may have higher arterial tissue factor expression and higher thrombin formation, and changes in tissue factor pathway coagulation inhibitor (TFPI) and thrombin activatable fibrinolysis inhibitor (TAFI) may be deleterious. Healthy postmenopausal women (n = 719) were randomized to hormone therapy [n = 357; opposed (n = 290) and unopposed (n = 67)] or no treatment (n = 362). Plasma TFPI and TAFI and the TFPI -287T/C and TAFI -438G/A polymorphisms were measured 5-6 years after randomization. Concentrations of TFPI were significantly lower in the hormone group than in the control group (P < 0.001) and in all genotypes of the TFPI polymorphism. Overall, concentrations of TAFI did not differ between the two groups but were reduced by hormone therapy in homozygotes for the rare TAFI -438 A allele (P < 0.05). The hormone effects on TFPI and TAFI were similar in smokers and non-smokers and in women using unopposed and opposed therapy. The observed decrease in TFPI may contribute to the increased cardiovascular risk associated with HRT.

Why might statins prevent venous thromboembolism: what needs to be done to know more?

Dyslipidaemia may be a risk factor for venous thromboembolism and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) may be protective. The current review outlines the cumulative evidence from both the basic and epidemiologic sciences for why this might be so and offers some directions for future research.

Treatment with cerivastatin in primary mixed hyperlipidemia induces changes in platelet aggregation and coagulation system components

Platelet activation, impairment of fibrinolysis, activation of the coagulation pathway, and dyslipidemia are important factors in the pathogenesis and progression of ischemic heart disease, and patients generally need to use an antiplatelet agent. Lipid-lowering cerivastatin, a novel 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, was administered to 20 patients with primary mixed hyperlipidemia for the assessment of the effect of cerivastatin on lipid levels, plasma fibrinogen concentration, factor VII, VIII, and X levels, plasminogen and antiplasmin concentrations, platelet count, and aggregation (adenosine diphosphate [ADP], collagen, and epinephrine induced). Assessments were made immediately after 2 months of a standard lipid-lowering diet, 4 weeks of placebo administration, and 4 weeks of cerivastatin treatment. Cerivastatin achieved significant reductions in triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels. The significant improvement of the lipid profile was associated with platelet aggregation reduction in vitro stimulated by ADP, collagen, and epinephrine (P < .05, P = .05, P < .005, respectively). Significantly lower levels of factor VII and fibrinogen were observed (P = .001, P < .0001) immediately after cerivastatin treatment. No significant differences were detected in factor VIII level, plasminogen and antiplasmin concentrations, and platelet count after cerivastatin treatment. It was concluded that cerivastatin in mixed hyperlipidemia can exert beneficial changes on specific hemostatic variables and platelet aggregation in addition to its positive effects on plasma lipid values.

Tissue factor pathway inhibitor and other endothelium-dependent hemostatic factors in elderly individuals with normal or impaired glucose tolerance and type 2 diabetes

OBJECTIVE

Impaired glucose tolerance (IGT) is believed to be a prediabetic phase that precedes the development of type 2 diabetes. In elderly subjects, IGT and diabetes are both independently associated with the occurrence of cardiovascular disease. Endothelial damage precedes atherosclerotic changes of the vascular wall. Therefore, several markers of endothelial dysfunction were examined in elderly subjects with IGT and elderly patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Von Willebrand factor (vWF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor type-1 (PAI-1), and thrombomodulin were studied as markers of endothelial dysfunction in a population-based study of elderly subjects with normal glucose tolerance (NGT) or IGT and type 2 diabetes. In addition to these endothelium-dependent factors, we also investigated tissue factor pathway inhibitor (TFPI) activity in relation to metabolic parameters and cardiovascular risk factors.

RESULTS

All data were adjusted for age. Increased levels of vWF antigen, t-PA antigen, and PAI-1 activity were seen in the IGT and diabetic group compared with the NGT group. TFPI activity and thrombomodulin levels were increased in all elderly subjects, and no differences were seen between the groups. There was a positive association between HbA(1c) and TFPI activity and vWF antigen. Fasting blood glucose levels correlated with vWF antigen, t-PA antigen, and PAI-1 activity, whereas urine albumin excretion correlated with TFPI activity, vWF antigen, and PAI-1 activity. Serum insulin levels correlated strongly not only with vWF antigen and t-PA antigen but also with PAI-1 activity. This correlation did not change after further adjustment for serum glucose and HbA(1c), which may suggest that in the elderly subjects, impaired fibrinolysis is probably associated with insulin resistance. There were no associations between the endothelium-dependent hemostatic factors and lipids, except for a negative correlation between HDL cholesterol and thrombomodulin.

CONCLUSIONS

In elderly subjects with IGT, several endothelium-dependent hemostatic factors are already consistently increased, indicating endothelial damage in this stage.

Improved fibrinolysis after 1-year treatment with HMG CoA reductase inhibitors in patients with coronary heart disease

The study was aimed to investigate the effect of two different statins on the levels of haemostatic variables reflecting procoagulant and fibrinolytic activity in patients with coronary heart disease (CHD), with the hypothesis that statins might beneficially modify these levels. Fifty-eight patients were randomized to treatment with atorvastatin (n=28) or simvastatin (n=30) for 1 year. The starting dose in both groups was 20 mg/day. Fasting blood samples were collected before and after 12-month treatment for determinations of fibrinogen, prothrombin fragment 1+2 (F1+2), plasma D-dimer, soluble tissue factor, tissue plasminogen activator (tPA) antigen, tPA activity, plasminogen activator inhibitor type-1 activity (PAI-1 activity) and serum D-dimer as a global test of fibrinolytic activity. In the total population, improved fibrinolytic activity was observed after 1 year with increased levels of serum D-dimer (P=.001) and tPA activity (P=.024) and a reduction in tPA antigen (P=.048). No statistically significant changes were observed in any of the measured coagulation variables. Separately examined, an improved fibrinolytic profile was seen in the atorvastatin group with a significant increase in serum D-dimer (P=.005), a borderline increase in tPA activity (P=.083) and a borderline reduction in tPA antigen (P=.069). Within the simvastatin group, a reduction in prothrombin F1+2 was observed (P=.038). The differences in changes between the groups were statistically significant only for global fibrinolysis (serum D-dimer, P=.046). In conclusion, an improved fibrinolytic profile was observed after statin treatment, most pronounced with atorvastatin. The results indicate that the drugs promote a profibrinolytic profile, and may in part explain the benefit of statin treatment rendered in the prevention of CHD.

Diet and drug therapy: a dynamic duo for reducing coronary heart disease risk

A large proportion of the United States population requires aggressive low-density lipoprotein (LDL) cholesterol- lowering therapy to meet the new treatment guidelines established by the National Cholesterol Education Program Adult Treatment Panel III. This has further widened the gap between the number of people being treated compared with those who should be treated. Moreover, many people being treated do not meet their LDL cholesterol goal. Diet and healthy lifestyle practices remain the cornerstone of treatment to lower LDL cholesterol. Pharmacologic therapy has assumed an increasingly important role in reaching LDL cholesterol goals. Diet and healthy-lifestyle interventions have been shown to augment the benefits of cholesterol-lowering drugs. Together, this dynamic duo provides the most effective clinical means identified to date for maximally lowering LDL cholesterol levels.

Serum lipids and regulation of tissue factor-induced coagulation in middle-aged men

Formation of an occlusive thrombus by exposure of tissue factor (TF) to circulating blood and subsequent triggering of coagulation by TF-activated factor VII (FVIIa) complexes on ruptured atherosclerotic plaques is thought to be a key event in myocardial infarction. Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of TF-induced coagulation in which the anticoagulant function most probably is restricted to free TFPI in human plasma. The present study was undertaken to assess the interrelations between serum lipids and components of TF-induced coagulation in 234 apparently healthy men aged 36-56 years recruited from the general population. Plasma free TFPI antigen (Ag) was positively correlated (P < .001) with total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, apolipoprotein B (apoB-100), fibrinogen, total amount of FVII (FVIIam), coagulation activity of factor VII (FVIIc), and FVIIa. The significant predictors for free TFPI Ag were total cholesterol, triglycerides, fibrinogen, FVIIc, and age, which explained 33% of the plasma variation in free TFPI Ag assessed by multiple regression analysis. A highly significant (P < .0001) linear trend for increase in atherogenic lipids (i.e., total cholesterol and triglycerides), FVII (i.e., FVIIc and FVIIa), and fibrinogen across quartiles of TFPI Ag was demonstrated after adjustment for confounders. These findings may indicate a compensatory increase in plasma free TFPI with lipid and hemostatic risk factors for atherothrombotic diseases in healthy middle-aged men.

Level of plasma tissue factor pathway inhibitor is inversely correlated with intraarterial diastolic pressure in subjects who underwent coronary angiography

There are only a few studies of the relationship between hemostatic abnormalities and intraarterial pressure, so the present study investigated the association of various newer lipid and hemostatic variables with intraarterial pressure levels. Levels of total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, triglyceride, lipoprotein-(a), remnant-like particle cholesterol, cholesteryl ester transfer protein, uric acid, blood glucose, fibrinogen, free form of tissue factor pathway inhibitor (TFPI), C-reactive protein, serum amyloid A protein, anti-Chlamydia pneumoniae immunoglobulin G and immunoglobulin A, and apolipoproteins (apo) A-I, B, and E were measured in 176 patients who underwent diagnostic coronary angiography. Intraarterial blood pressure was determined from central aortic pressure using a standard fluid-filled catheter-external transducer system. Multivariate regression analyses showed that TFPI level was the only independent factor associated with aortic diastolic pressure. The linear regression equation demonstrated a significant negative correlation of TFPI level with aortic diastolic pressure (r=-0.395, p=0.0011). With respect to the association with other parameters, the TFPI level showed significant correlations between the HDL-C level and the apo A-I level, both in the overall patients and in the patients with coronary artery stenosis. This is the first evidence that the level of the plasma free form of TFPI is inversely correlated to aortic diastolic pressure.

Beneficial effects of statins in coronary artery disease--beyond lowering cholesterol

OBJECTIVE

To review the benefits of statins in coronary artery disease management beyond their cholesterol-lowering effects.

DATA SOURCES

A MEDLINE search (1966-May 2000) was conducted using the following terms: lovastatin, pravastatin, simvastatin, atorvastatin, fluvastatin, cerivastatin, endothelium, plaque stabilization, antithrombotic effects.

STUDY SELECTION

English-language human studies and case reports.

DATA EXTRACTION

Studies published demonstrating other mechanisms of statins' clinical beneficial effects were evaluated and reviewed.

DATA SYNTHESIS

The understanding of the pharmacologic effects of statins has led to the realization that the benefits of these agents extend beyond simply lowering cholesterol. These properties include beneficial effects on vessel endothelial tissue; decreased low-density lipoprotein oxidation and inflammation; ability to stabilize atherosclerotic plaques and perhaps promote regression; proliferative effects on smooth-muscle growths, possibly strengthening atherosclerotic plaques; antithrombotic effects by inhibiting platelet aggregation and stimulation of fibrinolytic factors; and improvement of blood viscosity and flow. With these actions, statins may benefit the situation of long-term atherosclerotic plaque formation and the setting of acute coronary syndrome.

CONCLUSIONS

Further large-scale studies are needed to determine the clinical importance and validity of these postulated beneficial effects of statins.

Effects of HMG-CoA reductase inhibitor on hemostasis

Clinical trials of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor (statin) therapy have demonstrated improvement in coronary atherosclerosis progression and reduction in risk of cardiovascular events. However, improvement in cardiovascular end-points is incompletely explained by the baseline or treated LDL cholesterol level. The beneficial effects of statins on clinical events may involve nonlipid mechanisms that modify hemostasis. Local activation of platelets and thrombus formation adjacent to atheromatous plaques, especially where ruptured or eroded, are now recognized to be of pathophysiological importance in the acute and chronic clinical expression of coronary heart disease. Thus, favorable effects of statins on hemostasis may be relevant to decreasing or delaying the progression and clinical manifestations of atherosclerosis.

Differences in free and total tissue factor pathway inhibitor, and tissue factor in peripheral artery disease compared to healthy controls

Tissue factor (TF) is one of the major initiators of coagulation and raised plasma levels have been found in various cardiovascular diseases. TF activity is, however, regulated by tissue factor pathway inhibitor (TFPI), and alteration in levels of TF and/or TFPI may thus relate to thrombogenesis and atherogenesis. To investigate possible abnormalities in TF and free TFPI (i.e. unbound to TF) and total TFPI among patients with peripheral artery disease (PAD), we studied 42 patients (mean age 57, 35 men) with objectively proven (by ABPI/Doppler) disease and 42 age- and sex- matched healthy controls. TF, free TFPI and total TFPI were measured in citrated plasma by ELISA. TF was higher in the patients with PAD compared to controls (275+/-122 pg/ml versus 158+/-60, P<0.0001) but levels of total TFPI were lower in the patients (43+/-10 ng/ml versus 50+/-15, P=0.021). There was no significant difference in levels of free TFPI between patients and controls (7.2+/-1.5 ng/ml in controls, 7.5+/-1. 6 among patients, P=0.39). Within the control patients, levels of free and total TFPI were significantly correlated (Spearman r=0.51, P=0.001) but in the patients with PAD this correlation was poor (r=0. 21, P=0.178). We suggest that reduced levels of total TFPI and raised levels of TF may contribute to the process of atherogenesis and the increased risk of thrombosis among patients with cardiovascular disease.

Cell and molecular biology of the assembly and secretion of apolipoprotein B-containing lipoproteins by the liver

Triglycerides are one of the most efficient storage forms of free energy. Because of their insolubility in biological fluids, their transport between cells and tissues requires that they be assembled into lipoprotein particles. Genetic disruption of the lipoprotein assembly/secretion pathway leads to several human disorders associated with malnutrition and developmental abnormalities. In contrast, patients displaying inappropriately high rates of lipoprotein production display increased risk for the development of atherosclerotic cardiovascular disease. Insights provided by diverse experimental approaches describe an elegant biological adaptation of basic chemical interactions required to overcome the thermodynamic dilemma of producing a stable emulsion vehicle for the transport and tissue targeting of triglycerides. The mammalian lipoprotein assembly/secretion pathway shows an absolute requirement for: (1) the unique amphipathic protein: apolipoprotein B, in a form that is sufficiently large to assemble a lipoprotein particle containing a neutral lipid core; and, (2) a lipid transfer protein (microsomal triglyceride transfer protein-MTP). In the endoplasmic reticulum apolipoprotein B has two distinct metabolic fates: (1) entrance into the lipoprotein assembly pathway within the lumen of the endoplasmic reticulum; or, (2) degradation in the cytoplasm by the ubiquitin-dependent proteasome. The destiny of apolipoprotein B is determined by the relative availability of individual lipids and level of expression of MTP. The dynamically varied expression of cholesterol-7alpha-hydroxylase indirectly influences the rate of lipid biosynthesis and the assembly and secretion lipoprotein particles by the liver.

Effects of lipids and lipoproteins on thrombosis and rheology

Atherosclerotic plaque rupture and erosions precipitate thrombus formation and may lead to an acute ischemic syndrome. Lipids and lipoproteins modulate the expression and/or function of thrombotic, fibrinolytic and rheologic factors, and thereby influence hemostasis and potential tissue damage resulting from vascular injury. Triglyceride-enriched lipoproteins are accompanied by elevations in factor VII clotting activity, plasminogen activator inhibitor (PAI-1) and viscosity of blood and plasma. Low density lipoprotein (LDL) promotes platelet activation and tissue factor expression and LDL levels correlate with levels of vitamin K dependent coagulation factors and fibrinogen. Conversely, LDL inhibits tissue factor pathway inhibitor (TFPI) which limits activation of the extrinsic coagulation pathway. High density lipoprotein (HDL) has anti-atherothrombotic properties that result from inhibition of platelet and erythrocyte aggregation, reduced blood viscosity and suppression of tissue factor activity and PAI-1 activity and antigen levels. The effects of lipids and lipoproteins on hemostasis and rheology may have important implications for the clinical sequelae following plaque disruption and erosion.

Direct effects of statins on the vascular wall

The beneficial effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on coronary events have generally been attributed to their hypocholesterolemic properties. Mevalonate and other intermediates of cholesterol synthesis (isoprenoids) are necessary for cell proliferation and other important cell functions; thus effects other than cholesterol reduction may help to explain the antiatherosclerotic properties of statins. Recently we provided in vitro and in vivo evidence of decreased smooth-muscle cell (SMC) proliferation and migration by fluvastatin and simvastatin, but not by pravastatin, independent of plasma cholesterol reduction. The ability of fluvastatin to interfere with arterial SMC proliferation at therapeutic concentrations (0.1-1 microM) prompted us to investigate the pharmacologic activity of sera from 10 patients treated with fluvastatin, 40 mg once daily, on the proliferation of cultured human arterial myocytes. Pravastatin, 40 mg once daily, displays a lipid-lowering activity similar to that of fluvastatin without affecting SMC proliferation and was investigated as a control for assessing this non-lipid-related effect of fluvastatin. Fluvastatin and pravastatin, given for 6 days to patients with type IIa hypercholesterolemia, resulted in a similar decrease in low-density-lipoprotein (LDL) cholesterol. However, the addition of 15% whole-blood sera from patients treated with fluvastatin to the culture medium resulted in a 43% inhibition of cholesterol synthesis in SMCs (p < 0.01) that mirrored the pharmacokinetic profile of fluvastatin. When SMC proliferation was investigated, a significant inhibition of cell growth (-30%; p < 0.01) was detected with sera obtained 6 h after the last dose. No effect on SMC proliferation or cholesterol biosynthesis was observed when sera from patients treated with pravastatin were evaluated. These results suggest that statins exert a direct antiproliferative effect on the arterial wall, beyond their effects on plasma lipids, which could prevent significant cardiovascular disease.

Fluvastatin and tissue factor pathway inhibitor in type IIA and IIB hyperlipidemia and in acute myocardial infarction

Tissue factor pathway inhibitor (TFPI) is a serine protease inhibitor that regulates tissue factor-induced blood coagulation. In an open-label 8-week study, 20 hypercholesterolemic patients (10 type IIa and 10 type IIb) were enrolled and given fluvastatin 40 mg once daily at bedtime. At baseline (after a 4-week controlled diet) and at week 8, total cholesterol, total triglycerides and lipoprotein subfractions were assessed. TFPI antigen levels were measured at the same time by ELISA. We also measured TFPI concentrations in 10 control subjects and in 10 patients at the time of and ten days after acute myocardial infarction. In type IIa patients fluvastatin reduced total cholesterol levels by 26% and LDL-cholesterol by 30% (P < 0.001); in type IIb, fluvastatin significantly reduced total cholesterol levels by 24% (P < 0.001). In both dyslipidemic groups the baseline total TFPI levels were significantly higher than in the control group (P < 0.002). The therapeutic lipid-lowering effect was paralleled by a significantly reduction of total TFPI antigen concentrations from 132 +/- 23 to 71 +/- 37 ng/mL (P < 0.001) in type IIa and from 120 +/- 30 to 91 +/- 29 ng/mL (P < 0.05) in type IIb patients; in control subjects total TFPI levels were 81 +/- 22 ng/mL; however the lipoprotein-bound TFPI antigen subfractions did not differ significantly in the treated and control groups. In patients with recent myocardial infarction there was a significant reduction from day 0 to day 10 in total TFPI antigen levels, from 120 +/- 48 ng/mL to 80 +/- 16 ng/mL (P < 0.05). The reported reduction of TFPI antigen levels after fluvastatin treatment could be a sign of normalization of an up-regulated clotting system rather than an unfavourable reduction of a natural anticoagulant.

Tissue factor pathway inhibitor in complex with low density lipoprotein isolated from human plasma does not possess anticoagulant function in tissue factor-induced coagulation in vitro

Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of the extrinsic coagulation system. In human plasma 70-85% is associated with apoB-containing lipoproteins whereas 10-20% exists in a carrier free form. The purpose of the present study was to assess the anticoagulant function of TFPI in complex with low density lipoproteins (LDL) on tissue factor (TF)-induced coagulation in vitro. LDL-TFPI complexes were isolated by preparative density gradient ultracentrifugation, LDL-free TFPI by preparative gel filtration and the anticoagulant properties were assessed by a diluted prothrombin time assay (dPT). LDL-free TFPI (0-0.46 U/ml) added to the dPT mixture, caused a prominent dose-dependent prolongation of dPT (0-42.2 sec.) which could be abolished by the addition of blocking anti-TFPI IgG. Contrary, increasing amounts of LDL-bound TFPI (0-4.0 U/ml) shortened dPT by 11.4 sec at the highest concentration. LDL-bound TFPI was not immunodetected by anti-TFPI IgG directed against the distal portion of the C-terminus, and appeared on Western blotting with a major band at 67 kDa and a weak band at 34 kDa which suggest that LDL-bound TFPI lack anticoagulant function due to carboxy terminal truncation. Our data provide evidence for the hypothesis that the anticoagulant function of TFPI is restricted to its carrier free form in human plasma.

Effectiveness and safety of low-dose pravastatin and squalene, alone and in combination, in elderly patients with hypercholesterolemia

A double-blind, placebo-controlled study was conducted to compare the efficacy and safety of low-dose (10 mg) prevastatin and squalene (860 mg), either alone or in combination therapy, with placebo in the treatment of elderly patients with hypercholesterolemia. Ambulatory elderly patients (N = 102) were assigned in randomized fashion to receive active treatment or placebo for 20 weeks after a single-blind placebo lead-in period of 8 weeks. Total cholesterol and triglyceride levels in plasma were at least 250 mg/dL and less than 300 mg/dL, respectively. Concentrations of lipids and lipoproteins were measured, and clinical laboratory tests included liver function and creatine kinase determinations. Pravastatin 10 mg daily was more effective than squalene in reducing total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides and in increasing levels of high-density lipoprotein (HDL) cholesterol. Combination therapy significantly reduced total cholesterol and LDL cholesterol and increased HDL cholesterol to a greater extent than either drug alone. Adverse events and clinical laboratory abnormalities were generally mild and transient in all groups, and all but two patients finished the study. The incidence of side effects was low; myopathy did not occur. Coadministration of pravastatin and squalene combined the specific effects of the two drugs on lipoprotein concentrations. This combination may be useful and more cost-effective in elderly patients with hypercholesterolemia, who might have a higher incidence of side effects when using larger doses of pravastatin alone.

Low levels of tissue factor pathway inhibitor (TFPI) in two out of three members of a family with thrombophilia

We describe a family with severe thrombosis of early onset in two siblings and in their father. Low levels of TFPI were detected in the two siblings (50% and 45% respectively) but their parents have normal TFPI levels. All other hemostatic proteins associated with thrombophilia, as well as blood lipids were within the normal range. The release of TFPI, after heparin administration, was proportionally reduced in the two siblings as compared with controls. The study of this family does not permit to conclude that low levels of TFPI are responsible for their thrombophilia. In the future the study of more families with similar characteristics may allow to know the inheritance of TFPI and whether there is a causal relationship between low levels of TFPI and thrombosis.

Influences of lipid-modifying agents on hemostasis

Drugs affecting lipid metabolism may influence, to a variable extent, the hemostatic system, that is, platelet activation, fibrinogen, and fibrinolysis. These effects may or may not be linked to the activity of these compounds on the lipid/lipoprotein profile. For this reason it may be important to consider the effects of hypolipidemic drugs on the different aspects of hemostasis, because this may allow a better understanding of their clinical use, as well as, eventually, a more proper selection in individual patients. Among the major lipid-lowering agents, fibric acids belong to a multifaceted series of abnormal fatty acids known to interact with a liver nuclear receptor, in turn activating fatty acid catabolism. A similar activity may be exerted by n-3 fatty acids from fish, as well as by other chemically related or unrelated compounds. Among fibric acids all but gemfibrozil can reduce fibrinogen levels; this last drug can, however, apparently activate fibrinolysis. Among the selective cholesterol-lowering medications, both resins and HMG CoA reductase inhibitors may reduce, in some patients, over prolonged periods of treatment, platelet sensitivity to major aggregants. This effect may be seen best with non-liver-selective agents (e.g., simvastatin), although recent data cast doubt on its constancy. A direct comparative evaluation of different HMG CoA reductase inhibitors on platelet aggregability has never been carried out. These last drugs may also reduce the circulating levels of the tissue factor pathway inhibitor (TFPI), transported by LDL in plasma, which is a potentially negative effect. A lipid-lowering molecule with antioxidant activity, for example, probucol, may also possibly play a role in controlling platelet activation.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of n-3 fatty acids on plasma lipids and lipoproteins and other cardiovascular risk factors in patients with hyperlipidemia

This review discusses the effects of dietary n-3 fatty acids on the plasma concentrations and metabolism of lipoproteins with a particular focus on work in human subjects. The influence of dietary n-3 fatty acids on the concentrations of plasma lipoproteins are affected by the amount of n-3 fatty acids as well as by the lipoprotein phenotype in the patients under investigation. On the basis of the observed changes in lipoproteins, dietary n-3 fatty acids exert the greatest effects on the concentrations of triglyceride-rich lipoproteins; their therapeutic potential is greatest in patients with hypertriglyceridemia. In addition to their effects on plasma lipoproteins, dietary n-3 fatty acids have been reported to exert potentially favorable effects on blood pressure, platelet function and viscosity. These effects may justify the use of supplements of dietary n-3 fatty acids in selected patients with hypertriglyceridemia to reduce the risk of atherosclerosis; however, the benefits of such therapy remain to be demonstrated.

Elevated plasma levels of vascular endothelial cell markers in patients with hypercholesterolemia

Hypercholesterolemia is associated with an increased incidence of vascular complications. To assess the actual degree of activation of coagulation systems and vascular disorders in hypercholesterolemia, plasma levels of vascular endothelial cell markers, such as thrombomodulin (TM), tissue-type plasminogen activator, plasminogen activator inhibitor-I (PAI-I), and von Willebrand factor, were measured in 51 patients with hypercholesterolemia. We also investigated the effects of Pravastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on plasma lipid, lipoprotein a, and hemostatic markers. The mean plasma levels of thrombin-antithrombin III complex (TAT), fibrinopeptide A (FPA), TM, and PAI-I were significantly elevated in hypercholesterolemia. Of the hemostatic markers, only TM was significantly increased in patients with ischemic heart diseases (IHD). The mean concentration of total cholesterol and levels of TAT, FPA, PAI-I, and TM were significantly reduced after the Pravastatin treatment. The PIC/TAT ratio was significantly increased in non-IHD patients after treatment, this was not the case in IHD patients. These findings suggested the presence of a thrombogenic state and vascular endothelial cell disorders in hypercholesterolemia; such a state might well be related to hypofibrinolysis.

HMG-CoA reductase inhibitor use in the aged. A review of clinical experience

While the benefit of cholesterol-lowering in the elderly has yet to be proven in clinical trials, individuals at high risk of coronary events who otherwise enjoy a good quality of life, should not be denied cholesterol-lowering therapy on the basis of age alone. Moreover, hypolipidaemic drugs are already extensively used in the aged. The HMG-CoA reductase inhibitors lovastatin, simvastatin and pravastatin are potent well tolerated hypolipidaemic therapies in young subjects. Although there have been few studies on their use in elderly subjects, the available data suggest the efficacy and safety of HMG-CoA reductase inhibitors in similar to that established for younger age groups.

Coagulation inhibition and activation in pancreatic cancer. Changes during progress of disease

BACKGROUND

To elucidate the disturbed hemostatic balance in patients with pancreatic cancer, the levels of plasma coagulation inhibition and coagulation activation were determined.

METHODS

Twenty-one patients with adenocarcinoma of the pancreas were followed from time of diagnosis until death, using plasma analyses of coagulation inhibitors and a molecular marker of coagulation activation (thrombin-antithrombin complex, TAT).

RESULTS

TAT was increased significantly at the time of diagnosis of pancreatic cancer compared with age-adjusted healthy control subjects (mean, 6.2 +/- 4.6 micrograms/l [standard deviation] versus 2.0 +/- 0.7 micrograms/l). It increased with disease progression (mean in the terminal phase, 14.1 micrograms/l; P < 0.05). Plasma levels of tissue factor pathway inhibitor (TFPI) also were increased significantly at the time of diagnosis compared with the control group (mean, 176 +/- 80% versus 127 +/- 29%; P < 0.05). The TFPI decreased to normal levels (121 +/- 40%) after surgical removal of the pancreatic tumor (n = 4) or relief of the cholestasis using a bypass procedure (n = 6). The TFPI levels increased significantly as the malignant disease progressed (from 1-3 months postoperatively to the terminal phase of disease; mean, 114 +/- 52% versus 154 +/- 60%). There was a significant positive correlation between TFPI levels and bilirubin levels; the correlation coefficient at diagnosis was 0.70 (P < 0.001). The levels of the coagulation inhibitors antithrombin, heparin cofactor II, protein C, and free protein S decreased significantly with disease progression compared with the normal values found at diagnosis.

CONCLUSIONS

The mechanism for TFPI increase in cancer is not known. It may be related to the preoperative cholestasis seen in this study, but the increased degree of coagulation activation also may contribute.

Comparative hypolipidemic effects of lovastatin and simvastatin in patients with heterozygous familial hypercholesterolemia

We have compared the effects of lovastatin and simvastatin on plasma lipoproteins, fibrinogen and urinary mevalonic acid excretion in twenty-three patients with heterozygous familial hypercholesterolemia. After a baseline period patients were randomly assigned to receive lovastatin or simvastatin at doses of 10, 20 and 40 mg twice daily, for a period of 2 months each, and then, after a 4-week wash-out period, all patients received the alternate drug for a similar period of therapy. Both drugs were well-tolerated and no patients were withdrawn due to side effects. Lipid values returned to baseline after discontinuation of therapy and no carry-over effect was observed. Treatment with lovastatin resulted in decreases in LDL cholesterol concentrations from 274 mg/dl at baseline to 211, 192 and 178 mg/dl, respectively, on doses of 20, 40 and 80 mg/day. Treatment with simvastatin reduced concentrations of LDL cholesterol to 194, 168 and 156 mg/dl, respectively, on doses of 20, 40 and 80 mg/day. Concentrations of HDL cholesterol increased on both drugs, but no dose response relationship was apparent. Both drugs reduced the 24-h urinary excretion of mevalonic acid, an intermediate in cholesterol biosynthesis, but the magnitude of decrease was similar with lovastatin and simvastatin. Small, but statistically non-significant decreases in fibrinogen occurred with both drugs. Patients who showed the greatest hypolipidemic effect during treatment with lovastatin also showed an excellent therapeutic response to simvastatin and vice versa. We conclude that, on a milligram per milligram basis, simvastatin is twice as potent as lovastatin in the treatment of familial hypercholesterolemia and that with both drugs, reductions in LDL cholesterol concentrations are accompanied by decreases in the urinary excretion of mevalonic acid.