Comparison of the hemodynamic and metabolic effects of low-dose hydrochlorothiazide and lisinopril treatment in obese patients with high blood pressure

Approach to Antihypertensive Therapy

Antihypertensive agents are commonly prescribed by physicians to prevent the long-term mortality from chronic hypertension. They are also given to improve survival in a number of conditions (eg, heart failure, coronary artery disease), independent of the effect on blood pressure. Several classes of antihypertensives are available with unique pharmacologic characteristics and adverse effects. Not all agents in the same class have identical effects, and careful selection of drugs based on the comorbid conditions is recommended.

Treatment of hypertension in obese patients

Obesity is a global pandemic and with its rise, its associated co-morbidities are increasing in prevalence, particularly uncontrolled hypertension. Lifestyle changes should be an anchor for the management of obesity-related hypertension; however, they are difficult to sustain. Drug therapy is often necessary to achieve blood pressure control. Diuretics, inhibitors of the renin-angiotensin system, and dihydropyridine calcium channel blockers are often used as first trio, with subsequent additions of mineralocorticoid receptor antagonists and/or dual alpha/beta blocking agents. While a number of agents are currently available, 50 % of hypertensive patients remain uncontrolled. A number of novel drug and invasive therapies are in development and hold significant potential for the effective management of obesity-related hypertension.

The renin-angiotensin system in the pathophysiology of type 2 diabetes

Increased activation of the renin-angiotensin system (RAS) has been related to cardiovascular disease and type 2 diabetes mellitus. Most randomized clinical trials have demonstrated that RAS blockade reduces the incidence of type 2 diabetes, which has been explained by improved insulin secretion and insulin sensitivity. In this review, an overview of the mechanisms that may underlie the association between the RAS and type 2 diabetes will be provided, with focus on skeletal muscle and adipose tissue function. This will include discussion of several human studies performed in our laboratory to investigate the metabolic and hemodynamic effects of the RAS, combining in vivo measurements of whole-body and tissue metabolism with molecular and immunohistochemical approaches. Available data suggest that the detrimental effects of the RAS on insulin secretion are mediated by a reduction in pancreatic blood flow and induction of islet fibrosis, oxidative stress as well as inflammation, whereas both impaired skeletal muscle function and adipose tissue dysfunction may underlie RAS-induced insulin resistance. Thus, although future studies in humans are warranted, current evidence supports that targeting the RAS in intervention studies may improve metabolic and cardiovascular function in conditions of insulin resistance like obesity and type 2 diabetes.

Medical complications of obesity and optimization of the obese patient for colorectal surgery

Obesity is a medical epidemic with an enormous impact on disease prevalence and health care utilization. In the preoperative period, an awareness of medical issues associated with obesity is an important part of the planning for surgical procedures. The authors highlight the diagnostic and treatment options for medical conditions commonly affecting the obese patient including diabetes, hypertension, coronary artery disease, and deep venous thrombosis.

Secondary hypertension: obesity and the metabolic syndrome

The epidemic of obesity in the United States and around the world is intensifying in severity and scope and has been implicated as an underlying mechanism in systemic hypertension. Obese hypertensive individuals characteristically exhibit volume congestion, relative elevation in heart rate, and high cardiac output with concomitant activation of the renin-angiotensin-aldosterone system. When the metabolic syndrome is present, insulin resistance and hyperinsulinemia may contribute to hypertension through diverse mechanisms. Blood pressure can be lowered when weight control measures are successful, using, for example, caloric restriction, aerobic exercise, weight loss drugs, or bariatric surgery. A major clinical challenge resides in converting short-term weight reduction into a sustained benefit. Pharmacotherapy for the obese hypertensive patient may require multiple agents, with an optimal regimen consisting of inhibitors of the renin-angiotensin-aldosterone system, thiazide diuretics, beta-blockers, and calcium channel blockers if needed to attain contemporary blood pressure treatment goals.

The effect of body mass index on fasting blood glucose after initiation of thiazide therapy in hypertensive patients

BACKGROUND

The prevalence of obesity, hypertension, and type 2 diabetes mellitus is increasing in the United States. In this setting, it is important to understand the effects of antihypertensives on glucose metabolism. We therefore examined the association between body mass index (BMI) (kg/m(2)) and fasting blood glucose (FBG) in subjects in whom thiazide antihypertensive therapy had been initiated.

METHODS

A retrospective observational study was carried out on individuals with hypertension who had been started on thiazide therapy. The subjects' age, thiazide dose, BMI, serum potassium, FBG, new onset of diabetes mellitus, and concurrent use of other antihypertensives were included in the analysis. Predictors of change in FBG were analyzed using multiple linear regression analysis, while predictors of new-onset diabetes mellitus were determined using multiple logistic regression.

RESULTS

A total of 2,624 individuals who had been started on thiazide therapy for hypertension were divided into quartiles of increasing BMI. FBG was found to be associated with baseline BMI and, after thiazide initiation, there was a step-wise increase in the magnitude of change in FBG with increasing BMI (P < 0.001 for both). Analysis using multiple linear regression found that BMI and baseline FBG predicted the magnitude of FBG change in subjects initiated on thiazide treatment (P < 0.001 for both). Analysis with logistic regression found that, after thiazide initiation, BMI, serum potassium baseline (P < 0.05 for both), and baseline FBG (P < 0.001) predicted the development of diabetes mellitus.

CONCLUSIONS

There is an overall increase in FBG in individuals who are started on treatment with thiazides for hypertension. The magnitude of change in FBG and the development of new-onset diabetes mellitus after thiazide initiation were associated with increases in BMI and baseline FBG. American Journal of Hypertension (2008) doi:10.1038/ajh.2007.75American Journal of Hypertension (2008); 21 4. 438-442 doi:10.1038/ajh.2007.75.

Effect of valsartan addition to amlodipine on insulin sensitivity in overweight-obese hypertensive patients

OBJECTIVE

The aim of the study was to evaluate the effect of valsartan/amlodipine combination on insulin sensitivity in overweight-obese hypertensive patients.

METHODS

After a 4-week placebo period, 58 overweight-obese (BMI >or=25 kg/m(2)) patients, with mild to moderate essential hypertension (DBP >95 and <110 mmHg, SBP >140 mmHg) were treated with amlodipine 5 mg od or valsartan 160 mg od or amlodipine 5 mg plus valsartan 160 mg od for 8 weeks according to a randomized, open-label, blinded end-point, cross-over study. At the end of the placebo period and each treatment period, blood pressure (BP) and insulin sensitivity (IS) (by euglycemic hyperinsulinemic clamp technique) were evaluated. IS was expressed as the amount of glucose infused during the last 30 min (glucose infusion rate, GIR) in mg/kg/min.

RESULTS

Valsartan/amlodipine combination produced a significantly greater decrease in SBP/DBP values (-22.3/16.7 mmHg, p<0.001 vs baseline) than valsartan (-15.2/11.7 mmHg, p<0.01 vs baseline) and amlodipine monotherapy (-16.1/12.6 mmHg, p<0.01 vs baseline). Both valsartan and amlodipine provided a significant increase in GIR (+1.24 mg/kg/min, p=0.036 vs baseline and +1.02 mg/kg/min, p=0.047, respectively), but such an increase was significantly greater with their combination (+1.82 mg/kg/min, p<0.01 vs baseline). These greater changes in IS were not related to BP changes.

CONCLUSION

Valsartan/amlodipine combination improved IS more than respective monotherapy beyond affording greater BP reductions. This strengthens the rationale to use valsartan/amlodipine combination in the treatment of overweight-obese hypertensives.

Effect of short-term ACE inhibitor treatment on peripheral insulin sensitivity in obese insulin-resistant subjects

AIMS/HYPOTHESIS

This study was designed to investigate the effect of short-term ACE inhibitor treatment on insulin sensitivity and to examine possible underlying metabolic and haemodynamic effects in obese insulin-resistant subjects.

METHODS

A randomised, double-blind placebo-controlled trial was performed in 18 obese insulin-resistant men (age, 53 +/- 2 years; BMI, 32.6 +/- 0.8 kg/m(2); homeostasis model assessment of insulin resistance, 5.6 +/- 0.5; systolic blood pressure [SBP], 140.8 +/- 3.2; diastolic blood pressure [DBP], 88.8 +/- 1.6 mmHg), who were free of any medication. The aim was to examine the effects of 2 weeks of ACE inhibitor treatment (ramipril, 5 mg/day) on insulin sensitivity, forearm blood flow, substrate fluxes across the forearm, whole-body substrate oxidation and intramuscular triacylglycerol (IMTG) content.

RESULTS

Ramipril treatment decreased ACE activity compared with placebo (-22.0 +/- 1.7 vs 0.2 +/- 1.1 U/l, respectively, p < 0.001), resulting in a significantly reduced blood pressure (SBP, -10.8 +/- 2.1 vs -2.7 +/- 2.0 mmHg, respectively, p = 0.01; DBP, -10.1 +/- 1.3 vs -4.2 +/- 2.1 mmHg, respectively, p = 0.03). Ramipril treatment had no effect on whole-body insulin-mediated glucose disposal (before: 17.9 +/- 2.0, after: 19.1 +/- 2.4 micromol kg body weight(-1) min(-1), p = 0.44), insulin-mediated glucose uptake across the forearm (before: 1.82 +/- 0.39, after: 1.92 +/- 0.29 micromol 100 ml forearm tissue(-1) min(-1), p = 0.81) and IMTG content (before: 45.4 +/- 18.8, after: 48.8 +/- 27.5 micromol/mg dry muscle, p = 0.92). Furthermore, the increase in carbohydrate oxidation (p < 0.001) and forearm blood flow (p < 0.01), and the decrease in fat oxidation (p < 0.001) during insulin stimulation were not significantly different between treatments.

CONCLUSIONS/INTERPRETATION

Short-term ramipril treatment adequately reduced ACE activity and blood pressure, but had no significant effects on insulin sensitivity, forearm blood flow, substrate fluxes across the forearm, whole-body substrate oxidation and IMTG content in obese insulin-resistant subjects.

Management of hypertension in overweight and obese patients: A practical guide for clinicians

The association between obesity and cardiovascular disease is well established, and up to 60% of overweight or obese patients have hypertension. Dietary interventions associated with modest weight loss are effective in controlling blood pressure and in reducing use of antihypertensive drug therapy in overweight and obese patients. However, long-term maintenance of weight loss is achieved only in a small proportion of patients. Orlistat and sibutramine may help to achieve and maintain weight loss but may not be sufficient to control blood pressure in overweight and obese hypertensive patients. Consequently, antihypertensive drug therapy is often necessary in addition to weight loss interventions. Few studies have investigated different antihypertensive drugs, specifically in overweight and obese patients with hypertension. Based on studies involving obese and nonobese patients, first-line treatment options include a diuretic alone or an angiotensin-converting enzyme (ACE) inhibitor alone. If monotherapy is inadequate for blood pressure control, combination therapy with diuretic and ACE inhibitor and/or combining either of these drugs with a calcium channel blocker are reasonable treatment options. Additional studies to further clarify the management of these patients are warranted.

Why blockade of the renin–angiotensin system reduces the incidence of new-onset diabetes

Recent trials have suggested that inhibitors of the renin-angiotensin system (RAS), such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), may reduce the incidence of new-onset diabetes in patients with or without hypertension and at high risk of developing diabetes. In this review, we critically evaluate the evidence from recent clinical trials for such a potential preventive effect of ACE inhibitors and ARBs, including a meta-analysis of these recent trials. The reduced incidence of diabetes in patients at high risk of developing diabetes by ACE inhibitors or ARBs has been explained by haemodynamic effects, such as improved delivery of insulin and glucose to the peripheral skeletal muscle, and non-haemodynamic effects, including direct effects on glucose transport and insulin signalling pathways, all of which decrease insulin resistance. There is now evidence that the pancreas may contain an in situ active RAS, which appears to be upregulated in an animal model of type 2 diabetes. Thus, ACE inhibitors and ARBs may act by attenuating the deleterious effect of angiotensin II on vasoconstriction, fibrosis, inflammation, apoptosis and beta-cell death in the pancreas, thereby protecting a critical beta-cell mass essential for insulin production. New evidence is presented that ACE inhibitors and ARBs may delay or prevent the development of insulin resistance and diabetes, for which novel mechanisms are suggested. The actions of agents that interrupt the RAS on insulin resistance, obesity and diabetes warrant further investigation in other animal models. Prospective clinical studies with the primary endpoint of the prevention of diabetes are now indicated to (i) further explore whether the inhibitors of the RAS are superior compared to other antihypertensive agents such as calcium channel blockers (CCBs) and (ii) to evaluate the potential beneficial effects of combination antihypertensive regimens on the development of diabetes.

Prevention and treatment of the metabolic syndrome

The prevalence of the metabolic syndrome is increasing owing to lifestyle changes leading to obesity. This syndrome is a complex association of several interrelated abnormalities that increase the risk for cardiovascular disease and progression to diabetes mellitus (DM). Insulin resistance is the key factor for the clustering of risk factors characterizing the metabolic syndrome. The National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III defined the criteria for the diagnosis of the metabolic syndrome and established the basic principles for its management. According to these guidelines, treatment involves the improvement of the underlying insulin resistance through lifestyle modification (eg, weight reduction and increased physical activity) and possibly by drugs. The coexistent risk factors (mainly dyslipidemia and hypertension) should also be addressed. Since the main goal of lipid-lowering treatment is to achieve the NCEP low-density lipoprotein cholesterol (LDL-C) target, statins are a good option. However, fibrates (as monotherapy or in combination with statins) are useful for the treatment of the metabolic syndrome that is commonly associated with hypertriglyceridemia and decreased high-density lipoprotein cholesterol (HDL-C) levels. The blood pressure target is < 140/90 mm Hg. The effect on carbohydrate homeostasis should possibly be taken into account in selecting an antihypertensive drug. Patients with the metabolic syndrome commonly have other less well-defined metabolic abnormalities (eg, hyperuricemia and raised C-reactive protein levels) that may also be associated with an increased cardiovascular risk. It seems appropriate to manage these abnormalities. Drugs that beneficially affect carbohydrate metabolism and delay or even prevent the onset of DM (eg, thiazolidinediones or acarbose) could be useful in patients with the metabolic syndrome. Furthermore, among the more speculative benefits of treatment are improved liver function in nonalcoholic fatty liver disease and a reduction in the risk of acute gout.

The Management of Hypertension in the Overweight and Obese Patient

The management of hypertension in the overweight and obese patient is a frequently encountered but under investigated clinical problem. The conventional management of such patients involves weight reduction with dietary therapy or a combined approach with dietary and anti-obesity drug therapy. However, long-term weight reduction, which is necessary to sustain blood pressure (BP) control, is not feasible in over 80% of patients. Anti-obesity therapy with orlistat has inconsistent effects on BP and may benefit only patients who have uncontrolled or non-medicated hypertension. Anti-obesity therapy with sibutramine may be associated with a modest worsening of BP control. Consequently, antihypertensive drug therapy is often required to supplement a weight reduction programme, and also in patients with severe hypertension or hypertension-associated end-organ damage. Treatment with a thiazide diuretic should be considered as first-line antihypertensive drug therapy in overweight and obese patients. ACE inhibitors or non-dihydropyridine calcium channel antagonists are reasonable alternatives where clinically indicated, or they can be used in combination with a thiazide diuretic if treatment with the diuretic alone is insufficient. If such treatment is inadequate for BP control, the addition or substitution of an alpha- or beta-adrenoceptor antagonist may be considered, although the latter can be associated with weight gain. Concurrent disease is an important determinant of first-line and supplementary antihypertensive drug therapy. Additional studies are needed to determine the long-term (>1 year) efficacy and safety of antihypertensive and anti-obesity management strategies in the overweight and obese hypertensive patient.

Modulation of metabolic control by angiotensin converting enzyme (ACE) inhibition

Angiotensin converting enzyme (ACE) inhibitors are a widely used intervention for blood pressure control, and are particularly beneficial in hypertensive type 2 diabetic subjects with insulin resistance. The hemodynamic effects of ACE inhibitors are associated with enhanced levels of the vasodilator bradykinin and decreased production of the vasoconstrictor and growth factor angiotensin II (ATII). In insulin-resistant conditions, ACE inhibitors can also enhance whole-body glucose disposal and glucose transport activity in skeletal muscle. This review will focus on the metabolic consequences of ACE inhibition in insulin resistance. At the cellular level, ACE inhibitors acutely enhance glucose uptake in insulin-resistant skeletal muscle via two mechanisms. One mechanism involves the action of bradykinin, acting through bradykinin B(2) receptors, to increase nitric oxide (NO) production and ultimately enhance glucose transport. A second mechanism involves diminution of the inhibitory effects of ATII, acting through AT(1) receptors, on the skeletal muscle glucose transport system. The acute actions of ACE inhibitors on skeletal muscle glucose transport are associated with upregulation of insulin signaling, including enhanced IRS-1 tyrosine phosphorylation and phosphatidylinositol-3-kinase activity, and ultimately with increased cell-surface GLUT-4 glucose transporter protein. Chronic administration of ACE inhibitors or AT(1) antagonists to insulin-resistant rodents can increase protein expression of GLUT-4 in skeletal muscle and myocardium. These data support the concept that ACE inhibitors can beneficially modulate glucose control in insulin-resistant states, possibly through a NO-dependent effect of bradykinin and/or antagonism of ATII action on skeletal muscle.

Response to six classes of antihypertensive medications by body mass index in a randomized controlled trial

Blood pressure increases with increasing body mass index (BMI) and BMI is linearly related to blood pressure in population studies. Obesity has been said to cause resistance to antihypertensive medications. We compared short-term and 1-year blood pressure response by BMI category and weight change with hydrochlorothiazide, atenolol, diltiazem-SR, captopril, clonidine, prazosin, or placebo in 1292 male veterans. Drug doses were titrated to achieve goal diastolic blood pressure <90 mm Hg over 4-8 weeks. Patients who achieved goal blood pressure were maintained for 1 year. BMI did not predict change in systolic, diastolic or pulse pressures during titration for any drug. At 1 year obese patients (BMI >30) were 2.5 times more likely to have diastolic blood pressure controlled by atenolol than normal weight (BMI <27) patients (p=0.01). Only prazosin patients gained weight: 1.7 lb (end-titration, p<0.0001; 1-year, p=0.02). Obesity does not appear to cause resistance to antihypertensive medications.

[Effectiveness of combined therapy at set doses in a cohort of hypertense patients not controlled by single therapy]

OBJECTIVE

To evaluate the effectiveness of the fixed dose of a lisinopril-hydrochlorothiazide combination treatment in the control of blood pressure, in poorly controlled high blood pressure people, treated with monotherapy.Design. Prospective observational study.Setting. Primary care frame.Participants. 931 patients (56.7% women) with an average age of 62.0+/-3 years, were included by 199 primary care physicians. 915 patients (98%) ended the study and finally they were included for the statistical analysis.

MAIN MEASUREMENTS

OMS/SIH recommendations on blood pressure measurement and diagnose of poor control were followed. Pulse pressure, body mass index and basic clinical analyses were assessed. Four continuation visits were made during six months.

RESULTS

Lisinopril-hidrochlorothiazide (20/12.5 mg) reduced significantly SBP (24.6 +/- 3.5 mm Hg) and DBP (14,3 +/- 0.7 mm Hg) (P<.001). Blood pressure control was only influenced by age (OR, 0.81; 95% CI, 0.71-0.92; P=.001). Pulse pressure was reduced in 10.4 +/- 4.3 mm Hg (P<.001). After 24 weeks of treatment, glycemic and lipidic profiles showed an improvement, as well as HbA1c in diabetic people.

CONCLUSIONS

In Primary care, a 52.8% of poorly controlled with monotherapy high blood pressure people were controlled by a combination of lisinopril-hydrochlorothiazide (20/12.5 mg). In addition, pulse pressure was decreased and both lipid and glucose blood profiles improved.

Renal and cardiovascular considerations for the nonpharmacological and pharmacological therapies of obesity-hypertension

Obesity-associated hypertension is a common disease that involves a complex pathogenesis. Failure to control hypertension (HTN) in obese subjects provides a great threat to their renal and cardiovascular functions. The treatment of obesity-associated HTN is often difficult, and requires nonpharmacological and/or pharmacological approaches. Weight reduction is the cornerstone of the therapies of obesity-HTN, as it reverses the multiple components of its pathogenesis. When weight loss cannot be sustained or fails, pharmacological means should then be used. Angiotensin-converting enzyme inhibitors (ACEI) are the drug of choice: they can reduce blood pressure, protect the kidney and heart, and improve the metabolic abnormalities in obese subjects. Angiotensin-2 type-1 receptor blockers have a renoprotective benefit similar to ACEI, and they provide an important alternative to the use of ACEI. Diuretics are very effective in African-American obese hypertensives, but small doses should be used to avoid adverse effects on metabolic profiles. Long-acting calcium channel blockers are also effective and have the advantage of no adverse metabolic effects. Nondihydropyridine calcium channel blockers may provide additional renal and cardiovascular protective effects. The beta-adrenergic receptor blockers can cause further weight gain and metabolic abnormalities in obese subjects; therefore, careful monitoring is needed. There are few clinical data that support the efficacy and benefit of centrally acting alpha-2 agonists and alpha-adrenergic receptor antagonists in the treatment of obesity-HTN.

Optimizing blood pressure control in the obese patient

Obesity is a major public health issue, and hypertension is one of the most common associated comorbidities. Current guidelines for optimal blood pressure levels in obese patients or for the treatment of obesity-hypertension do not provide specific recommendations that go beyond the rather general recommendation to lose weight. Based on the strong ties between obesity, hypertension, and type 2 diabetes, and the similarity of complications that occur in obesity-related hypertension and in hypertension associated with type 2 diabetes, it seems appropriate to explore the optimal blood pressure levels for obese hypertensive patients. Recently published studies underline the importance of weight reduction to reach this goal. Several lines of reasoning support the use of angiotensin converting enzyme inhibitors or angiotensin receptor blockers as the appropriate first-line therapy in obese patients with uncomplicated hypertension. Nondihydropyridine calcium channel blockers, a-blockers, or low-dose diuretics may be added when necessary. Clearly, further studies are needed to define target blood pressure levels in obese patients and to clarify the value of established and newer drugs, like angiotensin receptor blockers, for the treatment of obese hypertensive patients. The role of antiobesity drugs in the management of the obese hypertensive patient also remains to be defined.

Management of type 2 diabetes mellitus in the elderly: special considerations

The principles of managing type 2 diabetes mellitus in the elderly are no different from those in younger patients, but the priorities and therapeutic strategies need to be cautiously individualised. The objectives of treatment are to improve glycaemic control in a stepwise approach that involves nonpharmacological methods including diet and exercise, and pharmacological therapy including mixtures of oral antihyperglycaemic agents alone or in combination with insulin. Although the goals of treatment may be the same for elderly and younger patients, certain aspects of type 2 diabetes in the elderly require special consideration. Treatment decisions are influenced by age and life expectancy, comorbid conditions and severity of the vascular complications. Adherence to dietary therapy, physical activity, and medication regimens may be compromised by comorbid conditions and psychosocial limitations. Drug-induced hypoglycaemia has been the main consideration and the most serious potential complication. In addition, the long term macrovascular and microvascular complications of type 2 diabetes are a source of significant morbidity and mortality. Indeed, vascular and neuropathic complications are already present at the time of diagnosis in a significant number of patients, and the impact of improved diabetes control depends on the age and life expectancy of the patient. Age-related changes in pharmacokinetics and the potential for adverse effects and drug interactions should also be considered when choosing appropriate pharmacological therapy. In general, a conservative and stepwise approach to the treatment of the elderly patient with type 2 diabetes is suggested; treatment may be initiated with monotherapy, followed by early intervention with a combination of oral agents including a sulphonylurea as a foundation insulin secretagogue in addition to a supplemental insulin sensitiser. Insulin therapy is eventually required if significant hyperglycaemia [glycosylated haemoglobin (HbA1c) >8%] persists despite oral combination therapy. Combination therapy with evening insulin and a long-acting sulphonylurea such as glimepiride is an effective strategy to improve hyperglycaemia in the elderly patient with type 2 diabetes in whom polypharmacy with oral agents is unsuccessful. In addition, such a regimen is simple to follow for the patient who may not be able to adhere to a more complicated insulin regimen. Hyperglycaemia in the elderly can be managed well with practical intervention and a straightforward treatment plan to enhance compliance. Optimal glycaemic control should be possible for every patient if treatment is individualised; however, strict glycaemic control may not be achievable in all patients or even desirable in many elderly patients.

The metabolic syndrome and related cardiovascular risk

The metabolic syndrome is a complex association of several risk factors including insulin resistance, dyslipidemia, and essential hypertension. Insulin resistance has been associated with sympathetic activation and endothelial dysfunction, which are the main mechanisms involved in the pathophysiology of hypertension and its related cardiovascular risk. According to the Sixth Report of the Joint National Committee, and guidelines of the World Health Organization/International Society of Hypertension, the presence of multiple risk markers suggests that both hypertension and risk factors should be aggressively managed in order to obtain a better outcome. Primary prevention of obesity at different levels--individual, familial, and social-- starting early in childhood has proven to be cost effective, and will be mandatory to reduce the world epidemic of obesity and its severe consequences.

Choice of drug treatment for obesity-related hypertension: where is the evidence?

Hypertension and obesity are common medical conditions independently associated with increased cardiovascular risk. Many large epidemiological studies have demonstrated associations between body mass index and blood pressure, and there is evidence to suggest that obesity is a causal factor in the development of hypertension in obese individuals. Consequently, all hypertension management guidelines consider weight reduction as a first step in the management of increased blood pressure in obese individuals. Weight reduction may be achieved by behaviour modification, diet and exercise, or by the use of anti-obesity medications. However, the long-term outcomes of weight management programmes for obesity are generally poor, and most hypertensive patients will require antihypertensive drug treatment. Some classes of antihypertensive agents may have potentially unwanted effects on some of the metabolic and haemodynamic abnormalities that link obesity and hypertension, yet most hypertension guidelines fail to provide specific advice on the pharmacological management of obese patients. This may be because there are currently no studies examining the efficacy of specific antihypertensive agents in reducing mortality in obese hypertensive patients. This paper reviews the theoretical reasons for the differential use of the major classes of antihypertensive agents in the pharmacological management of obesity-related hypertension and also considers the potential role of anti-obesity agents.

Obesity and hypertension

Substantial evidence from epidemiological data supports a link between obesity and hypertension. However, the relationship between the two disorders is not straightforward and most likely represents an interaction of demographic, genetic, hormonal, renal, and hemodynamic factors. Age, race, and sex also modulate the strength of the association between obesity and hypertension. Hyperinsulinemia, which is characteristic of obesity, can contribute to the probability of developing hypertension by activating the sympathetic nervous system (SNS) and by causing sodium retention. The pressor effect of insulin in obesity may be further enhanced by the observation that its vasodilator action can be blunted in obese subjects. Preliminary data have shown that leptin, whose levels are increased in most obese individuals, can contribute to hypertension in obesity through its effects on insulin, SNS, and sodium excretion. The kidney may also have a role in the pathophysiology of hypertension in obesity. Abnormal renal sodium handling coupled with structural changes in the kidney of an obese patient can raise blood pressure. In addition, obesity is associated with distinct cardiovascular hemodynamic alterations and development of eccentric myocardial hypertrophy. Most of these obesity-associated abnormalities, as well as hypertension itself, can be reversed by weight loss. Furthermore, weight loss can prevent, or at least delay, the development of hypertension in patients with high-normal blood pressure. Weight reduction should be the first-line treatment in every obese hypertensive patient. However, the majority of patients will need pharmacologic intervention in conjunction with weight loss. Selection of antihypertensive agents in the overweight patient should take into account the mechanisms leading to hypertension and the metabolic abnormalities that characterize the obese patient.

Insulin resistance and hypertension

Insulin resistance, a common accompaniment of essential hypertension, increases cardiovascular risk both directly, and via its adverse effect on other cardiovascular risk factors. Decreasing insulin resistance by lifestyle modification including diet, weight loss, and physical exercise is an important component of therapy in all patients. With the exception of thiazide diuretics as monotherapy, the currently utilized classes of agent appear equally effective in lowering blood pressure in insulin resistant patients. Currently utilized agents do, however, differ substantially in their effect on insulin resistance and associated risk factors. Agents that diminish insulin resistance may have a rationale in treating insulin resistant patients with hypertension although a decisive recommendation about class of agent in this group of patients must await several prospective large scale trials currently underway. Lower intervention thresholds and lower therapeutic goals would appear to apply to hypertensive patients with insulin resistance especially in the presence of impaired glucose tolerance or overt diabetes mellitus.

Lisinopril versus hydrochlorothiazide in obese hypertensive patients: a multicenter placebo-controlled trial. Treatment in Obese Patients With Hypertension (TROPHY) Study Group

Because obesity-associated hypertension has unique hemodynamic and hormonal profiles, certain classes of antihypertensive agents may be more effective than others as monotherapy. Thus, we compared the efficacy and safety of the angiotensin-converting enzyme inhibitor lisinopril and the diuretic hydrochlorothiazide in a 12-week, multicenter, double-blind trial in 232 obese patients with hypertension. Patients with an office diastolic pressure between 90 and 109 mm Hg were randomized to treatment with daily doses of lisinopril (10, 20, or 40 mg), hydrochlorothiazide (12.5, 25, or 50 mg), or placebo. Mean body mass indexes were similar for all patients. At week 12, lisinopril and hydrochlorothiazide effectively lowered office diastolic (-8.3 and -7.7 versus -3.3 mm Hg, respectively; P<.005) and systolic (-9.2 and -10.0 versus -4.6 mm Hg, respectively; P<.05) pressures compared with placebo. Ambulatory blood pressure monitoring confirmed that lisinopril and hydrochlorothiazide effectively lowered 24-hour blood pressure compared with placebo (P<.001). Significant dose-response differences were observed between treatments. Sixty percent of patients treated with lisinopril had an office diastolic pressure <90 mm Hg compared with 43% of patients treated with hydrochlorothiazide (P<.05). Responses to therapies differed with both race and age. Neither treatment significantly affected insulin or lipid profiles; however, plasma glucose increased significantly after 12 weeks of hydrochlorothiazide therapy compared with lisinopril (+0.31 versus -0.21 mmol/L; P<.001). Hydrochlorothiazide also decreased serum potassium levels by 0.4 mmol/L from baseline. In conclusion, lisinopril was as effective as hydrochlorothiazide in treating obese patients with hypertension. Treatment with angiotensin-converting enzyme inhibitors may show greater efficacy as monotherapy at lower doses compared with thiazide diuretics, may have a more rapid rate of response, and may offer advantages in patients at high risk of metabolic disorders.

Lisinopril. A review of its pharmacology and clinical efficacy in elderly patients

Lisinopril, the lysine analogue of enalaprilat, is a long-acting angiotensin converting enzyme (ACE) inhibitor which is administered once daily by mouth. The efficacy of lisinopril in reducing blood pressure is well established in younger populations, and many trials now show it to be effective in lowering blood pressure in elderly patients with hypertension. In comparative and non-comparative clinical trials, 68.2 to 89.1% of elderly patients responded (diastolic pressure < or = 90 mm Hg) to > or = 8 weeks' lisinopril treatment. Age-related differences in antihypertensive efficacy do not appear to be clinically significant, and dosages effective in elderly patients tend to range from 2.5 to 40 mg/day. Dosages usually need to be lower in patients with significant renal impairment. In congestive heart failure, lisinopril 2.5 to 20 mg/day increases exercise duration, improves left ventricular ejection fraction and has no significant effect on ventricular ectopic beats. It is similar in efficacy to enalapril and digoxin and similar or superior to captopril on most end-points. Data from the GISSI-3 post-myocardial infarction trial show that lisinopril reduced mortality and left ventricular dysfunction when given for 42 days starting within 24 hours of the onset of infarction symptoms. Results at 6 weeks and 6 months were similar in elderly and younger patients. Elderly patients, however, among other subgroups, exhibited a strong reduction in risk of low ejection fraction after treatment (-25.5%). Economic studies suggest that lisinopril is cost saving compared with other ACE inhibitors in some markets. When given according to the GISSI-3 protocol, lisinopril appears to be one of the less expensive of the successful ACE inhibitor regimens for acute myocardial infarction. In other trials, patients with diabetic nephropathy and hypertension improved or did not deteriorate during lisinopril treatment. Blood pressure was controlled and reductions or trends towards reductions in albuminuria were observed. These reductions were similar to those in diltiazem, nifedipine and verapamil recipients, and greater than those in patients receiving atenolol. Lisinopril appears to reduce mortality in diabetic patients after myocardial infarction and may also improve neuropathy associated with diabetes. Lisinopril is well tolerated and the profile of adverse events seen is typical of ACE inhibitors as a class. There is a tendency for more elderly than younger patients to discontinue treatment, but this trend is not clearly related to the incidence of adverse events in these age groups. Drug interactions occur with few other agents and are usually clinically significant only between lisinopril and either diuretics or lithium. Lisinopril is, thus, an effective treatment for elderly patients with hypertension, congestive heart failure and acute myocardial infarction and has shown promising benefits in patients with diabetic nephropathy.

Metabolic manifestations of low-dose diuretics

Hypertension has been defined and treated as a disease of abnormal systolic and diastolic blood pressure. Recent data have, however, demonstrated that effective blood-pressure control has not resulted in the expected decrease in coronary artery disease. These findings are probably a result of hypertension being a complex inherited syndrome of cardiovascular risk factors, all of which are genetically linked and all of which contribute to the development of cardiovascular disease in these patients. Included in the hypertension syndrome are abnormalities of lipid profile, insulin resistance, changes in renal function, left ventricular hypertrophy and reduced arterial compliance. In many patients, high blood pressure is a late manifestation of this disease process. Since all cardiovascular risk factors contribute to heart disease in these patients, they should all be considered in the management of this disease process. Diuretics and beta blockers, when used at high doses, negatively impact lipid metabolism and insulin sensitivity, while angiotensin converting enzyme (ACE) inhibitors and calcium antagonists tend to have a neutral effect on these metabolic risk factors. These findings have resulted in decreased use of diuretics and beta blockers in favor of newer agents such as ACE inhibitors and calcium antagonists. However, recent data have demonstrated that when used at low doses (6.25 or 12.5 mg of hydrochlorothiazide), diuretics lack significant metabolic side effects while bringing about significant reductions in blood pressure. Thus, at these doses, hydrochlorothiazide is a useful drug in the treatment of hypertension, both as monotherapy and in combination therapy.