Effects of niceritrol on levels of serum lipids, lipoprotein(a), and fibrinogen in patients with primary hypercholesterolemia

Serum Lipoprotein(a) Levels and Their Association with Atherosclerotic Cardiovascular Disease in Japan

AIMS

To investigate the distribution of lipoprotein(a) (Lp(a)) and its association with atherosclerotic cardiovascular disease (ASCVD) in Japanese patients at high risk for ASCVD using a health insurance database.

METHODS

Between July 2013 and June 2021, patients eligible for ASCVD prevention according to the 2017 Japan Atherosclerosis Society (JAS) guidelines with documented Lp(a) test results were extracted from the Medical Data Vision claims database and divided into three groups: primary prevention high-risk (Group I), secondary prevention (Group II) and secondary prevention high-risk (Group III). Data on lipid levels, cardiovascular morbidity risk factors and lipid-lowering treatments were extracted.

RESULTS

Of 700,580 patients with documented low-density lipoprotein cholesterol (LDL-C), 2,967 (0.42%) were tested for Lp(a). In 2,170 eligible patients, the median [interquartile range] serum concentration of Lp(a) was 13.9 [7.5-24.6] mg/dL, with 151 patients (7.0%) above the recommended risk threshold of ≥ 50 mg/dL. Lp(a) levels increased with risk across all prevention groups. Being in the highest Lp(a) quintile (Q5) was associated with an increased frequency of ASCVD (28.9% versus 18.9% in the lowest quintile (Q1) for unstable angina; 18.7% versus 10.1% for myocardial infarction; 27.9% versus 17.0% for ischemic stroke). In the secondary prevention groups, the proportion of patients meeting an LDL-C target of ＜70 mg/dL decreased from 30.2% in Q1 to 19.0% in Q5 for Group II and from 32.9% to 16.3% for Group III.

CONCLUSIONS

Despite a high prevalence of Lp(a) ≥ 50mg/dL in Japanese patients at high risk for ASCVD, it found that the Lp(a) testing rate was very low.

Efficacy and tolerability of combined treatment with L-carnitine and simvastatin in lowering lipoprotein(a) serum levels in patients with type 2 diabetes mellitus

Lipoprotein(a) [Lp(a)] concentration is generally related to coronary artery disease (CAD) and cerebrovascular disease. However, at present, few interventions are available to lower Lp(a) concentrations. We investigated the effects of l-carnitine, co-administered with simvastatin, on hyper-Lp(a) in patients with type 2 diabetes mellitus. We conducted an open, randomised, parallel-group study, in one investigational center (University hospital). Fifty-two patients with type 2 diabetes mellitus, a triglyceride serum levels <400mg/dL (<4.5 mmol/L), and Lp(a) serum levels >20mg/dL (0.71 mmol/L) were randomised to receive simvastatin alone (n=26) or simvastatin plus l-carnitine (n=26) for 60 days. Simvastatin was administered, in both groups, at a dosage of 20 mg/day, while l-carnitine was administered at a dosage of 2g/day once daily. Both treatments were given orally. Serum levels of triglycerides, total cholesterol, LDL cholesterol, high-density lipoprotein (HDL) cholesterol, non-HDL cholesterol (total cholesterol minus HDL cholesterol), apolipoprotein B, and Lp(a) were measured at baseline and 60 days after starting treatment. No difference in time by groups (simvastatin and simvastatin plus l-carnitine) were observed in the reduction of LDL cholesterol, non-HDL cholesterol, and apoB serum levels. On the other hand, Lp(a) serum levels increase from baseline to 60 days in the simvastatin group alone versus a significant decrease in the combination group. Our findings provide support for a possible role of combined treatment with l-carnitine and simvastatin in lowering Lp(a) serum levels in patients with type 2 diabetes mellitus than with simvastatin alone. Our results strongly suggest that l-carnitine may have a role among lipid-lowering strategies.

Effect of niacin supplementation on fibrinogen levels in patients with peripheral vascular disease

This study demonstrates that niacin supplementation decreases plasma fibrinogen and low-density lipoprotein cholesterol in subjects with peripheral vascular disease randomized to receive niacin, warfarin, antioxidants, or placebo. Changes in fibrinogen levels are highly correlated with changes in low-density lipoprotein cholesterol (r = 0.61; p < 0.009) in subjects taking niacin.

Pentaerythritol tetranicotinate (niceritrol) decreases plasma lipoprotein(a) levels

We determined the most effective dosage of pentaerythritol tetranicotinate (niceritrol) to reduce plasma lipoprotein(a) [Lp(a)] levels in 44 Japanese patients (16 men and 28 women; mean age, 59.2 +/- 10.8 years) with hyperlipidemia types IIa, IIb, and IV. Patients received oral niceritrol at a dosage of 750 mg (3 tablets)/d for 8 weeks, followed by 1,500 mg (6 tablets)/d for 8 weeks. Administration of niceritrol 750 mg/d for 8 weeks decreased total and low-density lipoprotein (LDL) cholesterol in patients with type IIa hyperlipidemia and decreased triglycerides in patients with type IV hyperlipidemia, but did not affect Lp(a). However, niceritrol 1,500 mg/d for 8 weeks decreased Lp(a) in patients with initial Lp(a) levels greater than 30 mg/dL in addition to decreasing total and LDL cholesterol and triglycerides. These results suggest that the effective dosage of niceritrol to reduce the serum Lp(a) concentration in Japanese hyperlipidemic patients with a high Lp(a) level (> or = 30 mg/dL) is greater than 1,500 mg/d.

A cysteine-containing truncated apo A-I variant associated with HDL deficiency

We identified a 50-year-old Japanese woman with a novel mutation in the apolipoprotein (apo) A-I gene causing high-density lipoprotein (HDL) deficiency. The patient had extremely low HDL cholesterol and apo A-I levels (0.14 mmol/L and 0.8 mg/dL, respectively) but no evidence of coronary heart disease. However, she had bilateral xanthomas of the Achilles tendon, elbow, and knee joint as well as corneal opacities. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of serum followed by immunoblotting revealed that the patient's apo A-I had a lower molecular weight (24,000) than normal apo A-I. A partial gene duplication encompassing 23 nucleotides was found by DNA sequence analysis, resulting in a tandem repeat of bases 333 to 355 from the 5' end of exon 4. This tandem repeat caused a frameshift mutation with premature termination after amino acid 207. The frameshift gives rise to a predicted protein sequence that contains two cysteines. We designated this mutant as apo A-ISasebo. Apo A-ISasebo formed heterodimers with apo A-II and apo E in the patient's plasma and was associated with both the low-density lipoprotein and HDL fractions. The patient's cholesterol esterification rate and lecithin-cholesterol acyltransferase activity were reduced to about 30% of normal, although specific enzyme activity was unaffected, suggesting that it remained functionally normal. In addition, cholesteryl ester transfer activity was reduced to about half of normal. Thus, apo A-ISasebo was associated with complex derangements of lipoprotein metabolism.

New targets for lipid lowering and atherosclerosis prevention

The effectiveness of plasma lipid lowering in the clinic is well supported by a growing number of contributions, indicating the significant improvement in cardiovascular risk in primary and particularly in secondary prevention. While these studies have clearly indicated that the more potent agents for cholesterol reduction can provide a very effective help, other pathways of lipid metabolism have gained interest. These should be evaluated, in the hope of providing a more complete answer to the question of regulating lipid absorption, distribution, and tissue deposition. In addition to newer more potent systemic lipid-lowering drugs (in particular hydroxymethylglutaryl coenzyme A reductase inhibitors), nonsystemic agents, including cholesterol sequestrants, are receiving attention. Some of these are effective at low concentrations, thus providing a potentially powerful tool for plasma cholesterol regulation. Another area of development is that of acyl coenzyme A cholesterol acyltransferase inhibitors, i.e., drugs interfering with cholesterol esterification in tissues, particularly in the arterial wall; the major problem with these seems to be that of poor tolerability and of lack of definitive proof of plasma cholesterol reduction in humans. At present, drugs for the treatment of elevated lipoprotein(a) levels are not available, with few exceptions; in this case, a better understanding of the regulation of lipoprotein(a) metabolism and of the potential benefit of treatment seems necessary. Elevation of congenitally low high density lipoprotein cholesterol levels may also be an important target: microsomal enzyme inducers have been tested, but have not provided a clinically significant response; drugs with a mixed endocrine-hypolipidemic activity possibly may prove effective. Other targets, e.g., the correction of the lipoprotein pattern characterized by "small low density lipoprotein," and the development of drugs specifically acting on the cholesteryl ester transfer protein and lipoprotein lipase systems, are being explored. Finally, new areas of development are in recombinant apolipoproteins (apo's) and in gene therapy. One case, i.e., that of apo A-I/HDL, is entering the clinical field; the mutant apo A-IMilano might provide help because of a combined cholesterol removing/fibrinolytic activity. In the case of gene therapy, at present, data on low density lipoprotein receptor replacement are encouraging. Further options, such as gene transfer in the arterial wall to induce vascular protection/disobliteration of occlusions, are also being tested.

Long-term effects of niceritrol on serum lipoprotein(a) and lipids in patients with high levels of lipoprotein(a)

The long-term effects of niceritrol on lipoprotein(a) (Lp[a]), lipids, apolipoproteins, and fibrinogen and fibrinolytic factors were evaluated in 20 outpatients who had serum Lp(a) levels higher than 20 mg/dL. The mean ( +/- SE) levels of Lp(a) decreased from 33.6 +/- 2.3 mg/dL to 23.5 +/- 3.5 mg/dL after 12 months of niceritrol treatment (P < 0.01). Serum levels of triglycerides and apolipoprotein E decreased significantly and high-density lipoprotein cholesterol (HDL-C) increased significantly after 12 months (P < 0.05). There were no significant changes overall in fibrinogen and fibrinolytic factors, although fibrinogen concentrations showed a tendency to decrease with treatment. PAI-1 levels decreased significantly (P < 0.05) after 6 months of niceritrol treatment. A significant correlation of percent reduction between Lp(a) and apolipoprotein B levels (P < 0.01) was observed, suggesting that the Lp(a)-lowering effects of niceritrol may be due to niceritrol inhibition of apolipoprotein B synthesis, the major apolipoprotein of Lp(a). The ability of niceritrol to decrease Lp(a) levels and increase HDL-C levels, together with its tendency to lower fibrinogen levels, may help prevent coronary events in patients with high levels of Lp(a).

Lipoprotein(A): physiologic function, association with atherosclerosis, and effects of lipid-lowering drug therapy

OBJECTIVE

To review the structure and physiologic function of lipoprotein(a) [Lp(a)], review the association of Lp(a) with the development of atherosclerosis, and to critically evaluate the current literature regarding the effects of lipid-lowering drug therapy on Lp(a) serum concentrations.

DATA SOURCES

English language clinical and animal studies, abstracts, and review articles pertaining to Lp(a).

STUDY SELECTION AND DATA EXTRACTION

Relevant human and animal studies examining Lp(a)'s role in atherosclerosis and the effect of drug therapy on Lp(a) serum concentrations.

DATA SYNTHESIS

Possible physiologic functions and potential atherogenic mechanisms of Lp(a) are discussed. Evidence supporting the association of Lp(a) with atherosclerosis is presented. Studies evaluating the effects of lipid-lowering drug therapy on Lp(a) concentrations are reviewed and critiqued.

CONCLUSIONS

Lp(a) concentrations are correlated with the risk of atherosclerotic vascular disease (AVD) in both animals models and human studies. Drug therapies that have produced a consistent reduction in Lp(a) concentration include niacin alone or in combination with a bile acid sequestrant or neomycin. However, additional, larger studies are needed to evaluate the ability of drug therapies to specifically reduce elevated Lp(a) concentrations. Preliminary information suggests that reduction in Lp(a) concentrations may be associated with atherosclerotic plaque regression. Although drugs are available to lower Lp(a), one cannot conclude that lowering of Lp(a) is warranted until clinical trials demonstrating beneficial effects have been published.

Detection of a point mutation in cholesteryl ester transfer protein gene by polymerase chain reaction-mediated site-directed mutagenesis

We describe a method for the rapid and non-radioactive examination of DNA samples for a mutation of cholesteryl ester transfer protein using a polymerase chain reaction-mediated site-directed mutagenesis. CETP deficiencies were studied in 554 Japanese subjects (370 men, 184 women) aged between 18 and 91 (mean 48.3 years). By this method, we detected one homozygote and 3 heterozygotes of the CETP deficiency.