A randomized, double-blind study of gemfibrozil for the treatment of protease inhibitor-associated hypertriglyceridaemia

Therapeutic approaches to combating lipoatrophy: do they work?

Therapeutic strategies for combating HIV-associated lipodystrophy, and lipoatrophy in particular, have been a major focus of HIV clinical research. The initial impetus focused on protease inhibitor withdrawal strategies, which resulted in improved lipid profiles and insulin resistance but no change in subcutaneous or visceral adipose tissue. Nucleoside reverse transcriptase inhibitor withdrawal strategies, specifically withdrawal of thymidine analogues, have achieved greater success in the reversal of lipoatrophy. In particular, the MITOX extension study demonstrated a 35% improvement in limb fat over a 2 year period after a switch from a thymidine analogue to abacavir. However, recovery from lipoatrophy is a slow process, and limited access to and potential toxicities introduced by alternative therapies can limit switch strategies. The use of thiazolidinediones as agents to reverse lipoatrophy has, unfortunately, been shown to be ineffective, as have alternative therapeutic approaches with agents such as metformin, lipid-lowering agents and growth hormones. Although prevention of lipodystrophy may be the only definitive approach to combat this syndrome, the role of intermittent highly active antiretroviral therapy as a means of reducing the incidence, or slowing the development, of lipodystrophy is currently under evaluation.

The effects of HIV protease inhibitors on carbohydrate and lipid metabolism

Since the introduction of HIV protease inhibitors (PIs), disorders of glucose and lipid metabolism have emerged. In dissecting out the direct effect on lipid and glucose metabolism, it has become apparent that individual PIs have different effects on metabolism. Some PIs such as indinavir acutely induce insulin resistance. PIs have also been shown to cause other disorders of glucose metabolism, including impairment of insulin secretion and increased endogenous glucose production. Individual PIs also have different effects on lipid metabolism. Ritonavir predominantly increases triglyceride and very low-density lipoprotein cholesterol levels. Limited studies in HIV-negative volunteers suggest that several of the PIs do not increase low-density lipoprotein cholesterol levels. This review examines the direct effects of PIs on glucose and lipid metabolism by assessing prospective studies of HIV-infected and healthy normal volunteers, and in vitro studies.

The effects of HIV protease inhibitors on carbohydrate and lipid metabolism

Since the introduction of HIV protease inhibitors (PIs), disorders of glucose and lipid metabolism have emerged. In dissecting out the direct effect on lipid and glucose metabolism, it has become apparent that individual PIs have different effects on metabolism. Some PIs such as indinavir acutely induce insulin resistance. PIs have also been shown to cause other disorders of glucose metabolism, including impairment of insulin secretion and increased endogenous glucose production. Individual PIs also have different effects on lipid metabolism. Ritonavir predominantly increases triglyceride and very low-density lipoprotein cholesterol levels. Limited studies in HIV-negative volunteers suggest that several of the PIs do not increase low-density lipoprotein cholesterol levels. This review examines the direct effects of PIs on glucose and lipid metabolism by assessing prospective studies of HIV-infected and healthy normal volunteers, and in vitro studies.

Nevirapine and efavirenz elicit different changes in lipid profiles in antiretroviral-therapy-naive patients infected with HIV-1

BACKGROUND

Patients infected with HIV-1 initiating antiretroviral therapy (ART) containing a non-nucleoside reverse transcriptase inhibitor (NNRTI) show presumably fewer atherogenic lipid changes than those initiating most ARTs containing a protease inhibitor. We analysed whether lipid changes differed between the two most commonly used NNRTIs, nevirapine (NVP) and efavirenz (EFV).

METHODS AND FINDINGS

Prospective analysis of lipids and lipoproteins was performed in patients enrolled in the NVP and EFV treatment groups of the 2NN study who remained on allocated treatment during 48 wk of follow-up. Patients were allocated to NVP (n = 417), or EFV (n = 289) in combination with stavudine and lamivudine. The primary endpoint was percentage change over 48 wk in high-density lipoprotein cholesterol (HDL-c), total cholesterol (TC), TC:HDL-c ratio, non-HDL-c, low-density lipoprotein cholesterol, and triglycerides. The increase of HDL-c was significantly larger for patients receiving NVP (42.5%) than for patients receiving EFV (33.7%; p = 0.036), while the increase in TC was lower (26.9% and 31.1%, respectively; p = 0.073), resulting in a decrease of the TC:HDL-c ratio for patients receiving NVP (-4.1%) and an increase for patients receiving EFV (+5.9%; p < 0.001). The increase of non-HDL-c was smaller for patients receiving NVP (24.7%) than for patients receiving EFV (33.6%; p = 0.007), as were the increases of triglycerides (20.1% and 49.0%, respectively; p < 0.001) and low-density lipoprotein cholesterol (35.0% and 40.0%, respectively; p = 0.378). These differences remained, or even increased, after adjusting for changes in HIV-1 RNA and CD4+ cell levels, indicating an effect of the drugs on lipids over and above that which may be explained by suppression of HIV-1 infection. The increases in HDL-c were of the same order of magnitude as those seen with the use of the investigational HDL-c-increasing drugs.

CONCLUSION

NVP-containing ART shows larger increases in HDL-c and decreases in TC:HDL-c ratio than an EFV-containing regimen. Based on these findings, protease-inhibitor-sparing regimens based on non-nucleoside reverse transcriptase inhibitor, particularly those containing NVP, may be expected to result in a reduced risk of coronary heart disease.

Treatment of metabolic syndrome

The metabolic syndrome is intended to identify patients who have increased risk of diabetes and/or a cardiac event due to the deleterious effects of weight gain, sedentary lifestyle, and/or an atherogenic diet. The National Cholesterol Education Program's Adult Treatment Panel III definition uses easily measured clinical findings of increased abdominal circumference, elevated triglycerides, low high-density lipoprotein-cholesterol, elevated fasting blood glucose and/or elevated blood pressure. Three of these five are required for diagnosis. The authors also note that other definitions of metabolic syndrome focus more on insulin resistance and its key role in this syndrome. This review focuses on how treatment might affect each of the five components. Abdominal obesity can be treated with a variety of lower calorie diets along with regular exercise. Indeed, all of the five components of the metabolic syndrome are improved by even modest amounts of weight loss achieved with diet and exercise. For those with impaired fasting glucose tolerance, there is good evidence that a high fiber, low saturated fat diet with increased daily exercise can reduce the incidence of diabetes by almost 60%. Of note, subjects who exercise the most, gain the most benefit. Metformin has also been shown to be helpful in these subjects. Thiazolidinedione drugs may prove useful, but further studies are needed. Although intensified therapeutic lifestyle change will help the abnormal lipid profile, some patients may require drug therapy. This review also discusses the use of statins, fibrates, and niacin. Likewise, while hypertension in the metabolic syndrome benefits from therapeutic lifestyle change, physicians should also consider angiotensin converting enzyme inhibitor drugs or angiotensin receptor blockers, due to their effects on preventing complications of diabetes, such as progression of diabetic nephropathy and due to their effects on regression of left ventricular hypertrophy. Aspirin should be considered in those with at least a 10% risk of a coronary event over 10 years. Finally, three related conditions, nonalcoholic fatty liver disease, polycystic ovary syndrome and protease inhibitor associated lipodystrophy improve with therapeutic lifestyle change. Although metformin is shown to be useful with polycystic ovary syndrome, the data supporting drug therapy for the other syndromes is less convincing. More robust studies are needed before any firm recommendations can be made.

Fenofibrate is effective in treating hypertriglyceridemia associated with HIV lipodystrophy

OBJECTIVE

To determine the effectiveness of fenofibrate in treating hypertriglyceridemia associated with highly active antiretroviral therapy-associated HIV lipodystrophy syndrome (HLS).

METHODS

The authors recruited from their HIV metabolic clinic 55 adult patients with anthropomorphic changes consistent with HLS together with hypertriglyceridemia. The patients had no prior history of taking lipid-lowering medications and were free of liver and renal disease. They were on various highly active antiretroviral therapy regimens, and these regimens were not altered during the course of the study. Fenofibrate was started at 54 mg a day and the dose increased every 2 weeks to a maximum of 162 mg/day. Fasting lipid concentrations were measured at baseline and 6 months after the intervention.

RESULTS

At baseline, the fasting plasma concentrations of total cholesterol, triglyceride, and high-density lipoprotein (HDL) cholesterol were 259 +/- 11, 886 +/- 172, and 35.7 +/- 2.3 (mean +/- SEM) mg/dL, respectively. After 6 months of fenofibrate treatment, the fasting plasma concentrations were as follows: total cholesterol, 243 +/- 13; triglycerides, 552 +/- 104, and HDL cholesterol, 35.7 +/- 1.8 mg/dL. The decrease in fasting plasma triglyceride concentration was statistically significant (P < 0.05). Fenofibrate was well tolerated, and no subjects dropped out of the study.

CONCLUSION

Fenofibrate is an effective, well-tolerated treatment for hypertriglyceridemia associated with HLS.

Management of Dyslipidaemia in HIV-Infected Patients Receiving Antiretroviral Therapy

Dyslipidaemia associated with the treatment of HIV infection, particularly with the use of protease inhibitors (PIs), can raise cholesterol and triglyceride (TG) levels to the thresholds indicated for intervention. Recent evidence from epidemiological studies has shown that there are correlations between antiretroviral drug use and increased risks for, and incidences of, cardiovascular disease, including myocardial infarction and coronary heart disease. The primary goals of dyslipidaemia therapy for HIV patients are reductions of both low-density lipoprotein cholesterol (LDL-C) and markedly elevated TG levels. Dietary strategies and exercise programs may be tried, although these have shown inconsistent results. The two options for drug therapy are switching anti-retroviral agents and using lipid-lowering drugs. Each approach is associated with advantages and limitations, and the need to maintain viral suppression must be balanced with the need to treat abnormal lipid levels. Most drug switches replace the PI component with drugs from another antiretroviral class. Selection of drug therapy for lipid lowering depends on the type of dyslipidaemia predominating and the potential for drug interactions. The use of the statins pravastatin and atorvastatin is recommended for the treatment of patients with elevated LDL-C levels and gemfibrozil or fenofibrate for patients with elevated TG concentrations. Development of new PIs with more favourable effects on the lipid profile should be of benefit.

Cardiovascular risk factors in HIV-infected patients

Highly active antiretroviral therapy (HAART) commonly leads to persistent dyslipidemia and insulin resistance that appear likely to confer an increased incidence of cardiovascular disease (CVD). Both protease inhibitors (PIs) and, to a lesser extent, nucleoside analog reverse transcriptase inhibitors (NRTIs) appear to be involved, through direct metabolic effects of PIs and an indirect effect of PI and NRTI-related lipodystrophy. Several studies have found a variable relationship between CVD incidence and HAART, but these studies were not prospective and may not have been adequately powered. A variety of treatment strategies have been evaluated for dyslipidemia and insulin resistance, including lifestyle changes, drugs, and antiretroviral switching, but their relative safety, efficacy and roles are unclear. Although treatment of dyslipidemia and insulin resistance is commonly recommended, it should be remembered that such therapy is likely to be of greater benefit in those with a greater perceived CVD risk (i.e., multiple risk factors) and the lowest risk of HIV disease progression.

Effects of Metformin Or Gemfibrozil on the Lipodystrophy of HIV-Infected Patients Receiving Protease Inhibitors

Background

Hypertriglyceridaemia and insulin resistance are common in HIV-infected patients treated with protease inhibitors, particularly in those with lipodystrophy. Whether a therapeutic approach addressed to those metabolic abnormalities may have any impact on body fat is not clear.

Methods

Patients on stable antiretroviral therapy containing protease inhibitors, with abdominal obesity defined by increased waist-to-hip ratio, and plasma triglycerides >200 mg/dl, were randomized to receive blind medication consisting of metformin 850 mg, gemfibrozil 600 mg or placebo every 12 h for 1 year. Weight, height, waist and hip were measured, and fasting blood analyses, including at least CD4 cell count, plasma HIV-1 RNA, lactate, glucose, insulin, triglycerides, total, HDL and LDL cholesterol were performed at baseline and every 3 months. An oral glucose tolerance test, and assessments of total and regional fat by bioimpedance analysis and sonography, respectively, were also done at baseline, 6 and 12 months.

Results

One-hundred-and-eight patients were randomized to placebo ( n=36), gemfibrozil ( n=37) or metformin ( n=35). There was absolute loss of total and regional fat in the three arms without significant changes in the waist-to-hip ratio. However, the loss of fat in patients on gemfibrozil was significantly lower than in patients on placebo. No patient discontinued study drugs due to adverse effects.

Conclusion

In this population of HIV-infected patients, there was a loss of fat along time. The finding of relative preservation of fat associated with gemfibrozil therapy deserves further investigation in the search of potential effective therapies for lipodystrophy in HIV-infected subjects.