Treatments in Endocrinology最新文献

Weight reduction has been shown to improve glycemic control and cardiovascular risk factors associated with insulin resistance in obese individuals with type 2 diabetes mellitus. Therapeutic options for these patients include promoting weight loss (non-pharmacologic and pharmacologic treatment) and improving glycemic control, as well as treating common associated risk factors such as arterial hypertension and dyslipidemias. This article provides an overview of anti-obesity drugs used in the treatment of obese individuals with type 2 diabetes. The most widely investigated drugs, sibutramine and orlistat, result in modest, clinically worthwhile weight loss, with demonstrable improvements in many co-morbidities, among them, type 2 diabetes. Clinical trials with these anti-obesity medications in cohorts of obese diabetic patients have been reviewed as well as cathecolaminergic agents (diethylpropion [amfepramone], fenproporex, mazindol, ephedrine-caffeine combination), serotoninergic drugs (fenfluramine, dexfenfluramine, fluoxetine), and other drugs that have some action on weight loss (the antidiabetic agent metformin, anti-epileptic agents topiramate and zonisamide, and the antidepressive bupropion [amfebutamone]). These trials show variable benefits in terms of effects on glucose profiles.

Since the publication of the results of the Women's Health Initiative that described the risks of hormone replacement therapy, many women are actively seeking alternative treatments for menopausal symptoms. Black cohosh (Actaea racemosa, syn. Cimicifuga racemosa) is one such alternative that has been used in the US for over 100 years. To date only two cimicifuga extracts have been tested clinically, and the current recommended dosage is 40-80 mg/day. Review of the published clinical data suggests that cimicifuga may be useful for the treatment of menopausal symptoms, such as hot flashes, profuse sweating, insomnia, and anxiety. However, the methodology used in most of the trials is poor and further clinical assessment of cimicifuga is needed. In terms of safety, transient adverse events such as nausea, vomiting, headaches, dizziness, mastalgia, and weight gain have been observed in clinical trials. A few cases of hepatotoxicity have been reported, but a direct association with the ingestion of cimicifuga has not been demonstrated. The most recent data suggest that cimicifuga is not estrogenic.

Protracted critically ill patients have a seriously deranged metabolism, characterized by severe hyperglycemia, a disturbed serum lipid profile, and protein hypercatabolism. The severity of stress-induced hyperglycemia and insulin resistance in critically ill patients reflect the risk of death. A large, prospective, randomized, controlled study showed that maintaining normoglycemia with intensive insulin therapy reduces morbidity and mortality of surgical intensive care patients. These results were recently confirmed by two studies: one randomized controlled study of surgical intensive care patients and a prospective observational study of a heterogeneous patient population admitted to a mixed medical/surgical intensive care unit. The clinical benefits of intensive insulin therapy appear to be related both to prevention of glucose toxicity and to other direct insulin actions that are independent of glycemic control. Prevention of the toxic effects of high circulating glucose levels protected the ultrastructure and function of hepatocyte mitochondria. Benefits of the non-glycemic effects of insulin included partial correction of the deranged serum lipid profile and possibly counteraction of the catabolic state. In addition to its metabolic effects, intensive insulin therapy also prevented excessive inflammation and improved immune function.

The 'incretin effect' describes the phenomenon of an enhanced insulin response following oral ingestion of glucose compared with that after intravenous administration of glucose, leading to identical postprandial plasma glucose excursions. It accounts for up to 60% of the postprandial insulin secretion, but is diminished in patients with type 2 diabetes mellitus. Gastrointestinal hormones that promote the incretin effect are called incretins. Glucagon-like peptide-1 (GLP-1) is an important incretin. Under hyperglycemic conditions in humans, it stimulates insulin secretion and normalizes blood glucose levels. GLP-1 does not stimulate insulin secretion at normal glucose levels; therefore, it does not cause hypoglycemia. Furthermore, it inhibits glucagon secretion and delays gastric emptying. In vitro and animal data have demonstrated that GLP-1 increases beta-cell mass by stimulating islet cell neogenesis and by inhibiting the apoptosis of islet cells. The improvement of beta-cell function due to GLP-1 can be indirectly observed from the increased insulin secretory capacity of humans receiving such treatment. GLP-1 may represent an attractive therapeutic method for patients with type 2 diabetes because of its multiple effects, including the simulation of satiety in the CNS by acting as a transmitter or by crossing the blood brain barrier. Native GLP-1 is degraded rapidly upon intravenous or subcutaneous administration and is therefore not feasible for routine therapy. Long-acting GLP-1 analogs (e.g. liraglutide) and exendin-4 (exenatide) that are resistant to degradation, called 'incretin mimetics', are being investigated in clinical trials. Dipeptidyl peptidase-IV inhibitors (e.g. vildagliptin, sitagliptin, and saxagliptin) that inhibit the enzyme responsible for incretin degradation are also being studied.

Ibandronate is a nitrogen-containing bisphosphonate that has been approved for once-monthly administration in women with post-menopausal osteoporosis. Animal data suggest that the efficacy of the drug is determined by the cumulative dose rather than the frequency of administration. After treatment for 1 year in a large, randomized, double-blind, multicenter trial in women with postmenopausal osteoporosis, once-monthly ibandronate 150 mg was non-inferior to once-daily ibandronate 2.5 mg in terms of increases in mean lumbar spine (primary endpoint) and hip bone mineral density (BMD). In addition, once-monthly ibandronate 150 mg was significantly more effective than once-daily ibandronate for mean increase from baseline in lumbar spine BMD after 1 and 2 years. In another large, randomized, double-blind trial in women with osteoporosis, both once-daily and intermittent (>2-month between-dose interval [not approved]) ibandronate were significantly more effective than placebo in reducing the risk of new vertebral fractures, after treatment for 3 years. Once-daily and intermittent ibandronate also increased mean lumbar spine and hip BMD from baseline by significantly more than placebo. Oral once-monthly, once-daily, and intermittent ibandronate were generally well tolerated. Monthly ibandronate had a similar tolerability profile to once-daily ibandronate. The incidence of adverse events, including gastrointestinal events, with once-daily and intermittent ibandronate did not differ significantly from that with placebo. Significantly more women with osteoporosis preferred once-monthly ibandronate and found it more convenient than once-weekly alendronate, according to data from a 6-month, randomized, open-label, crossover study.

Patients with diabetes mellitus are at higher risk for cardiovascular events than those without diabetes. Furthermore, patients with diabetes have a characteristic 'lipid triad' of low high-density lipoprotein-cholesterol (HDL-C) levels, high triglyceride levels, and normal or slightly raised low-density lipoprotein-cholesterol (LDL-C) levels, with a preponderance of small, dense LDL-C particles. Current guidelines on preventing cardiovascular disease recognize the need not only to reduce LDL-C levels, but also to increase HDL-C and decrease triglyceride levels in diabetic patients. Some clinical trials of HMG-CoA reductase inhibitors (statins) have included large populations of diabetic patients. In some of these trials (such as 4S [Scandinavian Simvastatin Survival Study], CARE [Cholesterol and Recurrent Events] trial, and the HPS [Heart Protection Study]), HMG-CoA reductase inhibitor treatment significantly reduced cardiovascular events in diabetic patients, whereas in other trials (ALLHAT-LLT [Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial], ASCOT [Anglo-Scandinavian Cardiac Outcomes Trial]) the reductions were not significant. In CARDS (Collaborative Atorvastatin Diabetes Study), the first large HMG-CoA reductase inhibitor study to enroll only patients with type 2 diabetes, atorvastatin reduced cardiovascular events by 37% (p=0.001) compared with placebo. Fibric acid derivatives (fibrates), which are agonists of peroxisome proliferator-activated alpha receptors, exert their effects by altering the transcription of genes encoding proteins that control lipoprotein metabolism. Fibric acid derivatives are a valuable tool in the treatment of dyslipidemia in patients with diabetes, as they reduce plasma triglyceride levels by 30--50%, increase HDL-C levels by 10--15%, and shift the distribution of LDL subfractions towards larger, less atherogenic particles. The DAIS (Diabetes Atherosclerosis Intervention Study), which was conducted exclusively in patients with type 2 diabetes, found that fenofibrate reduces the progression of angiographic coronary artery disease. The VA-HIT (Veterans Affairs Cooperative Studies Program HDL-C Intervention Trial) showed that gemfibrozil reduced cardiovascular events in subgroups of diabetic patients. A large clinical event study, FIELD (Fenofibrate Intervention and Event Lowering in Diabetes), which is currently being completed, will provide further information on the value of fenofibrate for the reduction of cardiovascular risk in patients with diabetes.

Young women have become increasingly active in athletics during the 20th century. Those involved in sports that emphasize lean body type are at high risk for the development of menstrual dysfunction, including amenorrhea. This is mediated by an alteration in function of the hypothalamic-pituitary-ovarian (HPO) axis, with loss of normal secretion of luteinizing hormone, and subsequent lack of estrogen production. Disruption of the HPO axis appears to be dependent on the body's recognition of an energy imbalance, which may be due to a lack of compensatory caloric intake in the face of significant energy expenditure. Other pituitary hormones, such as triiodothyronine, growth hormone, and insulin-like growth factor-1 may also be affected. These metabolic changes have an impact on bone mineralization during a critical period in the development of bone mass. Recognition by physicians of the so-called 'female athlete triad', consisting of disordered eating, amenorrhea, and osteoporosis, may allow therapeutic intervention. Diagnosis of eating disorders and decreased bone mineral density can have significant impact on the health of the young athlete. Treatment is aimed at restoring normal menstrual function by increasing caloric intake to balance the increased energy demands of athletic participation. Concurrent treatment of the hypoestrogenemic state using estrogen replacement is controversial, but may aid in alleviating further loss of bone mass.