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Biomedical subjects

P H Chong

Publications and source records attributed to P H Chong.

7 recordsLinked to original sources

Clinically relevant differences between the statins: implications for therapeutic selection.

Although the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, share a common lipid-lowering effect, there are differences within this class of drugs. The low-density lipoprotein (LDL) cholesterol-lowering efficacy, pharmacokinetic properties, drug-food interactions, and cost can vary widely, thus influencing the selection of a particular statin as a treatment option. The statins that produce the greatest percentage change in LDL cholesterol levels are atorvastatin and simvastatin. Atorvastatin and fluvastatin are least affected by alterations in renal function. Fewer pharmacokinetic drug interactions are likely to occur with pravastatin and fluvastatin, because they are not metabolized through the cytochrome P450 (3A4) system. The most cost-effective statins, based on cost per percentage change in LDL cholesterol levels, are fluvastatin, cerivastatin, and atorvastatin. Awareness of these differences may assist in the selection or substitution of an appropriate statin for a particular patient.

Decision Making↗

Effect of acetaminophen on atherosclerosis.

OBJECTIVE: To evaluate the antioxidant effects of acetaminophen in atherosclerosis. DATA SOURCES: Experimental literature and abstracts accessed through MEDLINE (1966-February 2001). DATA SYNTHESIS: Atherosclerosis is an inflammatory disorder associated with coronary events. The oxidative stress burden resulting from excess pro-oxidant free radical formation contributes to oxidative modification of low-density lipoprotein (lipid peroxidation) and is associated with atherosclerosis. Acetaminophen (phenol-like compound) may limit these key processes that are involved. The findings of earlier experimental laboratory tests and abstracts are evaluated. CONCLUSIONS: In vitro data suggest that acetaminophen may reduce lipid peroxidation, whereas animal data showed decreased progression of atherosclerosis. Further animal model and human studies are required to confirm these earlier findings.

Acetaminophen↗

The low-density lipoprotein cholesterol-lowering effect of pravastatin and factors associated with achieving targeted low-density lipoprotein levels in an African-American population.

STUDY OBJECTIVES: To describe the low-density lipoprotein cholesterol (LDL)-lowering effect of pravastatin in African-American patients and to identify factors associated with achieving National Cholesterol Education Program (NCEP)-defined target levels. DESIGN: Retrospectively defined cohort study. SETTING: Large, government-owned, teaching hospital. PATIENTS: Eighty-four African-American patients starting therapy with pravastatin in October-November 1997. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Whether or not target LDL concentrations were achieved was used to measure efficacy. Stepwise logistic regression identified the target LDL, baseline LDL, and baseline high-density lipoprotein cholesterol (HDL) as significant predictors of achieving the target. The proportion of patients achieving their target LDL when that target was below 160, below 130, and 100 mg/dl or below was 64%, 32%, and 13% (p=0.004), respectively. Medical record review identified the reasons for not achieving target as incorrect drug regimen, inadequate lipid monitoring, and noncompliance. CONCLUSION: These results indicate that substantial numbers of patients receiving lipid-lowering therapy are not meeting NCEP-defined targets and that with increased drug monitoring and compliance, improvements in achieving NCEP target LDL levels could be realized.

Black or African American↗

Periodontal disease and atherosclerotic cardiovascular disease: confounding effects or epiphenomenon?

Recent evidence suggests that periodontal disease may predispose to atherosclerotic cardiovascular disease. Data support mechanisms of host-derived local and systemic proinflammatory responses similar to atherosclerosis, consisting of monocytic-derived cytokines and other inflammatory mediators, which are induced by periodontal pathogens and its endotoxin, lipopolysaccharide. These mechanisms may contribute to the start of vascular endothelial dysfunction and further sequelae leading to atherosclerosis. Experimental evidence and biologic plausibility appear to support this proposal. However, clinical evidence from a MEDLINE search from January 1966-December 1999 proposed a weak or no correlation primarily due to confounding factors. The aim of care is to reduce vulnerable pathogens from the infected periodontium by standard treatment; however, new approaches appear promising. Increased awareness of a potential link among infective agents, immunoinflammatory processes, and atherosclerosis may clarify clinical implications.

Cardiovascular Diseases↗

Current, new and future treatments in dyslipidaemia and atherosclerosis.

The new therapeutic options available to clinicians treating dyslipidaemia in the last decade have enabled effective treatment for many patients. The development of the HMG-CoA reductase inhibitors (statins) have been a major advance in that they possess multiple pharmacological effects (pleiotropic effects) resulting in potent reductions of low density lipoproteins (LDL) and prevention of the atherosclerotic process. More recently, the newer fibric acid derivatives have also reduced LDL to levels comparable to those achieved with statins, have reduced triglycerides, and gemfibrozil has been shown to increase high density lipoprotein (HDL) levels. Nicotinic acid has been made tolerable with sustained-release formulations, and is still considered an excellent choice in elevating HDL cholesterol and is potentially effective in reducing lipoprotein(a) [Lp(a)] levels, an emerging risk factor for coronary heart disease (CHD). Furthermore, recent studies have reported positive lipid-lowering effects from estrogen and/or progestogen in postmenopausal women but there are still conflicting reports on the use of these agents in dyslipidaemia and in females at risk for CHD. In addition to lowering lipid levels, these antihyperlipidaemic agents may have directly or indirectly targeted thrombogenic, fibrinolytic and atherosclerotic processes which may have been unaccounted for in their overall success in clinical trials. Although LDL cholesterol is still the major target for therapy, it is likely that over the next several years other lipid/lipoprotein and nonlipid parameters will become more generally accepted targets for specific therapeutic interventions. Some important emerging lipid/lipoprotein parameters that have been associated with CHD include elevated triglyceride, oxidised LDL cholesterol and Lp(a) levels, and low HDL levels. The nonlipid parameters include elevated homocysteine and fibrinogen, and decreased endothelial-derived nitric oxide production. Among the new investigational agents are inhibitors of squalene synthetase, acylCoA: cholesterol acyltransferase, cholesteryl ester transfer protein, monocyte-macrophages and LDL cholesterol oxidation. Future applications may include thyromimetic therapy, cholesterol vaccination, somatic gene therapy, and recombinant proteins, in particular, apolipoproteins A-I and E. Non-LDL-related targets such as peroxisome proliferator-activating receptors, matrix metalloproteinases and scavenger receptor class B type I may also have clinical significance in the treatment of atherosclerosis in the near future. Before lipid-lowering therapy, dietary and lifestyle modification is and should be the first therapeutic intervention in the management of dyslipidaemia. Although current recommendations from the US and Europe are slightly different, adherence to these recommendations is essential to lower the risk of atherosclerotic vascular disease, more specifically CHD. New guidelines that are expected in the near future will encompass global opinions from the expert scientific community addressing the issue of target LDL goal (aggressive versus moderate lowering) and the application of therapy for newer emerging CHD risk factors.

Anticholesteremic Agents↗

Glycoprotein IIb/IIIa receptor antagonists in the management of cardiovascular diseases.

Recent studies of the effects of glycoprotein (GP) IIb/IIIa receptor antagonists on the clinical outcomes of patients with cardiovascular diseases are reviewed. The GP IIb/IIIa receptor antagonists studied include abciximab (a murine monoclonal antibody); eptifibatide (a synthetic peptide); and tirofiban, lamifiban, xemilofiban, sibrafiban, and lefradafiban (synthetic nonpeptides). A majority of clinical trials of GP IIb/IIIa receptor antagonists have been performed in patients with unstable angina or acute myocardial infarction and in patients undergoing percutaneous coronary interventions in whom an intracoronary thrombus may lead to ischemic complications. There is abundant evidence that GP IIb/IIIa receptor antagonists reduce the risk of death, acute myocardial infarction, and urgent revascularization procedures in high- and low-risk patients undergoing percutaneous coronary interventions. Abciximab remains the most studied of these agents in interventional settings. Data are accumulating on synthetic peptide and nonpeptide GP IIb/IIIa receptor antagonists that also demonstrate lower rates of death and ischemic complications in the treatment of acute coronary syndromes. In patients who have had a successful response to intravenous GP IIb/IIIa receptor antagonists, oral agents may represent an option for secondary prevention. Additional studies are required in order to determine further uses for these agents. A growing body of evidence supports the role of GP IIb/IIIa receptor antagonists in invasive and pharmacologic treatment approaches to acute coronary syndromes.

Abciximab↗

Atorvastatin calcium: an addition to HMG-CoA reductase inhibitors.

Atorvastatin calcium is an HMG-coenzyme A (CoA) reductase inhibitor that was approved by the Food and Drug Administration on December 17, 1996. Like other such agents, it inhibits the action of HMG-CoA reductase and thereby decreases endogenous cholesterol synthesis, leading to a decrease in circulating low-density lipoprotein cholesterol. In addition to its effect on lipoprotein profile, atorvastatin reduces triglycerides to a greater extent than other HMG-CoA reductase inhibitors. These actions occur in a dose-dependent fashion. The adverse effect profile is similar to that of other agents in this class. Indications for atorvastatin include primary hypercholesterolemia as well as other lipid disorders.

Animals↗