Comparison of the effects of atenolol and nifedipine on glucose, insulin, and lipid metabolism in patients with hypertension

Safety and tolerability of β-blockers: importance of cardioselectivity

Cardioselective β-blockade is generally well tolerated in practice and contraindications to this therapy are uncommon. β-blockers are a diverse therapeutic class, and their individual tolerability profiles are influenced strongly by their pharmacodynamic effects across different adrenergic receptors. Bisoprolol, probably the β-blocker with the highest selectivity for blockade of β1- vs. β2-adrenoceptors, does not block β2-adrenoceptors to an appreciable extent at doses in therapeutic use. Side-effects often attributed to β-blockers, such as erectile dysfunction and adverse metabolic effects are uncommon with bisoprolol and other β-blockers used at doses which only block β1-adrenoceptors. Cautious use of a cardioselective β-blocker is not contraindicated in people with chronic obstructive pulmonary disease or asthma and the outcomes benefits of β-blockers in patients with coronary heart disease or heart failure are also apparent in patients with concurrent COPD. Starting with a low dose and titrating upwards carefully is important for optimising the tolerability of a β-blocker. Most people with hypertension will receive combination antihypertensive therapy in practice, and the low-dose combination therapy approach provides a useful strategy for optimising the efficacy and tolerability of a regimen that includes a β-blocker, compared with up-titrating an existing monotherapy.

A human-based multi-gene signature enables quantitative drug repurposing for metabolic disease

Insulin resistance (IR) contributes to the pathophysiology of diabetes, dementia, viral infection, and cardiovascular disease. Drug repurposing (DR) may identify treatments for IR; however, barriers include uncertainty whether in vitro transcriptomic assays yield quantitative pharmacological data, or how to optimise assay design to best reflect in vivo human disease. We developed a clinical-based human tissue IR signature by combining lifestyle-mediated treatment responses (>500 human adipose and muscle biopsies) with biomarkers of disease status (fasting IR from >1200 biopsies). The assay identified a chemically diverse set of >130 positively acting compounds, highly enriched in true positives, that targeted 73 proteins regulating IR pathways. Our multi-gene RNA assay score reflected the quantitative pharmacological properties of a set of epidermal growth factor receptor-related tyrosine kinase inhibitors, providing insight into drug target specificity; an observation supported by deep learning-based genome-wide predicted pharmacology. Several drugs identified are suitable for evaluation in patients, particularly those with either acute or severe chronic IR.

Association of an oral formulation of angiotensin-(1-7) with atenolol improves lipid metabolism in hypertensive rats

The β-adrenergic blockers and antagonists of the renin-angiotensin system (RAS) are among the drugs that present better results in the control of cardio-metabolic diseases. The aim of the present study was to evaluate the effect of the association of the β-blocker, atenolol, and an oral formulation of Ang-(1-7) on lipid metabolism in spontaneously hypertensive rats (SHR). The main results showed that SHR treated with oral formulation of Ang-(1-7) in combination to atenolol have an improvement of lipid metabolism with a reduction of total plasma cholesterol, improvement of oral fat load tolerance and an increase in the lipolytic response stimulated by the β-adrenergic agonist, isoproterenol, without modification of resting glucose or insulin sensitivity in adipocytes. In conclusion, we showed that administration of an Ang-(1-7) oral formulation in association with a β-blocker induces beneficial effects on dyslipidemia treatment associated with hypertension.

Metabolic effect of combined telmisartan and nifedipine CR therapy in patients with essential hypertension

BACKGROUND

In addition to exerting a blood pressure (BP)-lowering effect, telmisartan produces favorable metabolic effects via peroxisome proliferator-activated receptor γ activation. While a combination of telmisartan and a calcium channel blocker is often used to achieve a target BP level, the metabolic effects of this drug combination remain unclear. Therefore, this study evaluated the metabolic effects of telmisartan plus nifedipine controlled release (CR) therapy, in hypertensive patients without metabolic disease.

METHODS

Sixteen patients with essential hypertension, who had not undergone antihypertensive therapy in the previous 6 months, were studied. Patients were initiated on telmisartan (40 mg/day). If their office BP was not reduced to 140/90 mmHg after 6 weeks, nifedipine CR (20-40 mg per day) was added for 18 weeks. The other patients whose BP had achieved the target of 140/90 mmHg, continued only telmisartan.

RESULTS

Telmisartan reduced BP (174 ± 13/92 ± 10 to 143 ± 22/78 ± 11 mmHg; P < 0.01) at 6 weeks in 16 patients, but eight patients did not achieve target BP levels and required addition of nifedipine. Telmisartan also resulted in a reduction in the homeostatic model assessment of insulin resistance (HOMA-IR) (1.30 ± 0.65 to 1.10 ± 0.42; P < 0.05) at 6 weeks, but did not affect adiponectin or leptin levels. Addition of nifedipine (n = 8) resulted in a reduction in BP (158 ± 18/80 ± 13 to 131 ± 8/73 ± 13 mmHg; P < 0.01) at 18 weeks, but did not affect the HOMA-IR (1.10 ± 0.40 to 1.02 ± 0.56; ns). In patients who did not require addition of nifedipine (n = 8), BP levels remained nearly identical at 18 weeks (127 ± 13/73 ± 9 to 128 ± 13/68 ± 8 mmHg; ns), and HOMA-IR also remained nearly identical.

CONCLUSIONS

Telmisartan produced a favorable metabolic effect in hypertensive patients without preexisting metabolic disorders. Addition of nifedipine CR produced further BP-lowering effects, and resulted in maintenance of metabolic indices.

Metabolic Effects of Pindolol and Propranolol in a Double-Blind Cross-Over Study in Hypertensive Patients

Metabolic effects of pindolol and propranolol were investigated in a randomised study of double-blind, double-dummy design in 39 Caucasians with newly detected hypertension. Each active treatment period was 6 months long. A euglycaemic hyperinsulinaemic clamp test was done to measure insulin sensitivity, and i.v. glucose tolerance was investigated with insulin determinations. Lipoprotein concentrations were quantified and lipoprotein lipase activities were determined in muscle and adipose tissue and in plasma after heparin injection. The blood pressure was significantly reduced by both regimes. The insulin sensitivity index was decreased by 34% during propranolol treatment and by 17% during pindolol treatment. The insulin concentrations in plasma were elevated at the end of the i.v. glucose tolerance test but were not high enough to compensate for the insulin resistance, so HbA1c and glucose concentrations were increased. A significant reduction of lipoprotein lipase activity in skeletal muscle during propranolol treatment probably explains the pronounced increase in serum triglyceride concentration during propranolol treatment despite lower free fatty acids and higher lipoprotein lipase activity in adipose tissue. These changes of lipoprotein lipase activity were not correlated to the changes in insulin sensitivity. In summary, the metabolic effects were significantly less pronounced with pindolol than with propranolol, which probably can be ascribed to the agonistic effect of pindolol on beta 2 adrenoceptors.

Selective imidazoline agonist moxonidine in obese hypertensive patients

Obesity is the major risk factor for the development of hypertension. This association accentuates the risk of cardiovascular disease, as it is frequently accompanied by the components of the metabolic syndrome. This randomised open parallel study evaluated the chronic effects of moxonidine--a selective imidazoline receptor agonist--on blood pressure, plasma catecholamines, leptin, insulin and components of the metabolic syndrome in obese hypertensives. Amlodipine was used as the control drug. Our results showed that moxonidine and amlodipine significantly reduced blood pressure when measured using the oscillometric method and 24-hour blood pressure monitoring. Moxonidine therapy decreased systolic blood pressure from 160.4 +/- 2.4 to 142.1 +/- 3.3 mmHg (p < 0.005) and diastolic blood pressure from 102.4 +/- 1.3 to 89.7 +/- 1.6 mmHg (p < 0.005) after 24 weeks of treatment. Moxonidine administration reduced the supine arterial plasma levels of adrenaline from 63.2 +/- 6.6 to 49.0 +/- 6.7 pg/ml (p < 0.005), the supine arterial plasma levels of noradrenaline from 187.9 +/- 10.7 to 149.7 +/- 13.2 pg/ml (p < 0.01) and the orthostatic venous plasma levels of noradrenaline from 258.6 +/- 25.0 to 190.3 +/- 16.4 pg/ml (p = 0.03). Those variables were not changed by amlodipine. The plasma levels of leptin and insulin 120 min after a glucose load decreased after moxonidine administration from 27.2 +/- 3.5 to 22.6 +/- 2.9 pg/ml (p < 0.05) and from 139.7 +/- 31.2 to 76.0 +/- 15.2 U/ml (p < 0.05), respectively. Amlodipine, however, did not modify those variables. This study showed a comparable reduction in blood pressure with both antihypertensive drugs. Moxonidine decreased sympathetic nervous activity, improved insulin resistance and reduced the plasma levels of leptin.

Calcium antagonists

Calcium antagonists were introduced for the treatment of hypertension in the 1980s. Their use was subsequently expanded to additional disorders, such as angina pectoris, paroxysmal supraventricular tachycardias, hypertrophic cardiomyopathy, Raynaud phenomenon, pulmonary hypertension, diffuse esophageal spasms, and migraine. Calcium antagonists as a group are heterogeneous and include 3 main classes--phenylalkylamines, benzothiazepines, and dihydropyridines--that differ in their molecular structure, sites and modes of action, and effects on various other cardiovascular functions. Calcium antagonists lower blood pressure mainly through vasodilation and reduction of peripheral resistance. They maintain blood flow to vital organs, and are safe in patients with renal impairment. Unlike diuretics and beta-blockers, calcium antagonists do not impair glucose metabolism or lipid profile and may even attenuate the development of arteriosclerotic lesions. In long-term follow-up, patients treated with calcium antagonists had development of less overt diabetes mellitus than those who were treated with diuretics and beta-blockers. Moreover, calcium antagonists are able to reduce left ventricular mass and are effective in improving anginal pain. Recent prospective randomized studies attested to the beneficial effects of calcium antagonists in hypertensive patients. In comparison with placebo, calcium antagonist-based therapy reduced major cardiovascular events and cardiovascular death significantly in elderly hypertensive patients and in diabetic patients. In several comparative studies in hypertensive patients, treatment with calcium antagonists was equally effective as treatment with diuretics, beta-blockers, or angiotensin-converting enzyme inhibitors. From these studies, it seems that a calcium antagonist-based regimen is superior to other regimens in preventing stroke, equivalent in preventing ischemic heart disease, and inferior in preventing congestive heart failure. Calcium antagonists are also safe and effective as first-line or add-on therapy in diabetic hypertensive patients. Heart rate-lowering calcium antagonists (verapamil, diltiazem) may have an edge over the dihydropyridines in post-myocardial infarction patients and in diabetic nephropathy. Thus, calcium antagonists may be safely used in the management of hypertension and angina pectoris.

Effect of cilnidipine on insulin sensitivity in patients with essential hypertension

To clarify the effect of cilnidipine, a long-acting dihydropyridine Ca-antagonist that blocks both L- and N-type Ca(2+)-channels, on insulin sensitivity, cilnidipine at 5 to 10 mg/day was administered to ten patients with essential hypertension for 12 weeks. Mean age and body mass index (BMI) were 57.7 +/- 5.0 (SEM) years old and 27.1 +/- 1.5, respectively. Blood pressure, serum levels of catecholamines, glucose and lipid were determined before and after the treatment. Insulin sensitivity was also measured by a euglycemic hyperinsulinemic clamp method using an artificial pancreas (STG-22; Nikiso, Tokyo, Japan) before and after the treatment. Cilnidipine administration significantly lowered blood pressure from 154/96 to 137/84 mmHg (p<0.05). The glucose infusion rate was significantly increased by 20.8%, from 3.27 +/- 0.36 to 3.95 +/- 0.55 mg/kg/min (p<0.05). HbA1C and serum lipid levels such as total cholesterol and triglyceride were not altered. In addition, cilnidipine treatment did not significantly increase serum norepinephrine levels (278 +/- 25.2 vs. 332 +/- 33.6 pg/ml). Our results suggest that cilnidipine improves insulin sensitivity, possibly due to its exerting a vasodilatory action without stimulating sympathetic nervous activity.

Combined effect of ACE inhibitor and exercise training on insulin resistance in type 2 diabetic rats

The aim of this study was to investigate whether a combined treatment of ACE inhibitor and exercise training is more effective than either treatment alone in alleviating the insulin resistant states in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of type 2 diabetes. OLETF rats (25 weeks old) were randomly divided into 5 groups; sedentary control, exercise-trained, temocapril (ACE inhibitor; 2 mg/kg/day)-treated, with and without exercise, and losartan (AT1 receptor antagonist; 1 mg/kg/day)-treated. Long-Evans Tokushima Otsuka rats were used as a non-diabetic control. Body weight, the amount of abdominal fat and blood pressure were higher for OLETF rats than for control rats. However, glucose infusion rate (GIR), an index of insulin resistance, was decreased greatly in OLETF rats. The fasting levels of blood glucose, insulin and lipids were also increased in the diabetic strain. In OLETF rats, both temocapril and losartan reversed hypertensive states significantly, whereas GIR and hyperlipidemia were improved when rats were treated with ACE inhibitors, but not with the AT1 receptor antagonist. Exercise training decreased body weight and the amount of abdominal fat, and also increased GIR in parallel with improved dislipidemia. The combination of the ACE inhibitor with exercise training also improved obesity, hyperinsulinemia, dislipidemia and fasting level of blood glucose, and this combination resulted in the greatest improvement of insulin resistance. These results suggest that the combination of ACE inhibitor and exercise training may be a beneficial treatment for mixed diabetic and hypertensive conditions.

Prescribing patterns and therapeutic implications for diabetic hypertension in Bahrain

OBJECTIVE

To determine drug prescription patterns and the extent of conformity with World Health Organization/international Society of Hypertension (WHO/ISH) guidelines in diabetic hypertension.

DESIGN

Retrospective prescription-based survey.

SETTING

Seven primary-care health centers, comprising approximately one-third of primary-care health centers in Bahrain.

PATIENTS

Patients with type 2 diabetes and hypertension.

MAIN OUTCOME MEASURE

The prescribing pattern of antihypertensive and antidiabetic drugs.

RESULTS

Among a study sample of 1,463 patients with type 2 diabetes and hypertension, antidiabetic agents were prescribed as monotherapy in the following descending order: glyburide, gliclazide, insulin, and metformin. As combinations, sulfonylureas plus metformin was most popular, followed by metformin plus insulin, and sulfonylureas plus insulin. Sulfonylurea and metformin with insulin was rarely used. There was no significant difference in prescribing of glyburide and metformin between the elderly and young middle-aged diabetic patients; many patients older than 65 years were treated with a beta-blocker along with a long-acting sulfonylurea. Both as monotherapy and in overall use, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and calcium-channel blockers were most often prescribed. Among 35.5% patients treated with antihypertensive combinations, various two- and three-drug combinations of beta-blockers, ACE inhibitors, calcium-channel blockers, and diuretics were often used. The proportion of patients taking atenolol 100 mg/d was higher with combination regimens. Hydrochlorothiazide 25 mg or equivalent thiazide diuretics were extensively used.

CONCLUSIONS

The prescribing pattern of antihypertensives in diabetic hypertension differs in many instances from WHO/ISH guidelines, especially regarding the choice of antihypertensive drugs and their combinations. The appropriateness of antidiabetic drug choice is questionable in relation to the antihypertensive used.

Haemodynamic and metabolic effects of rilmenidine in hypertensive patients with metabolic syndrome X. A double-blind parallel study versus amlodipine

OBJECTIVE

To compare the effects of rilmenidine with those of amlodipine on blood pressure, glucose metabolism, plasma lipid concentration and fibrinolysis parameters.

DESIGN

A four-month randomized double-blind, parallel group study.

PATIENTS AND METHODS

Obese hypertensive patients with hypertriglyceridaemia (> or = 2.3 mmol/l) and impaired glucose tolerance (OMS-ADA) were included (n = 52). A placebo run-in period of 2 weeks was followed by 4 months of double-blind treatment with either rilmenidine or amlodipine. Blood pressure was recorded using a mercury sphygmomanometer. Glucose metabolism was evaluated by an oral glucose tolerance test

RESULTS

Of the 52 patients recruited, 47 (21 rilmenidine and 26 amlodipine) completed the 4-month treatment period. The intention-to-treat analysis showed a comparable reduction in systolic and diastolic blood pressure (SBP, DBP) with the two anti-hypertensive treatments (rilmenidine -13.9/-13.5 mmHg; amlodipine - 17.6/-15.0 mmHg). Insulin concentrations under basal conditions and 2 h after a standard oral glucose load did not change significantly after treatment in both groups. Plasma glucose under basal conditions and 2 h after a standard oral glucose load as well as the area under the plasma glucose concentration curve tended to decrease in the rilmenidine group and to increase in the amlodipine group so that the changes in these parameters were significantly different between the two study groups (P= 0.041, P = 0.042 and P = 0.015, respectively). Plasminogen activator inhibitor type 1 (PAI-1) antigen and PAI-1 activity were only decreased in the rilmenidine group (not statistically significant).

CONCLUSION

Our results demonstrate that rilmenidine and amlodipine have a comparable anti-hypertensive effect but only rilmenidine is able to improve glucose metabolism.

Management of patients with hypertension and diabetes mellitus: advances in the evidence for intensive treatment

Diabetes mellitus is common in patients with hypertension, and greatly increases the risk of cardiovascular disease, including myocardial infarction, stroke, and peripheral vascular disease. "The pharmacologic therapy of patients with hypertension and diabetes has been surrounded by controversy because of concerns about the metabolic effects of several antihypertensive agents, as well as concerns about the safety of calcium antagonists. The objective of this review is to re-evaluate the management of diabetic patients with hypertension in light of the latest clinical trials. We also review the importance of intensive blood pressure control in these patients.

Improvement of insulin resistance in essential hypertension by long-acting Ca antagonist benidipine

To investigate whether the long-acting Ca channel blocker, benidipine improves insulin resistance in patients with essential hypertension, insulin sensitivity was measured using the steady state plasma glucose (SSPG) method in 11 or 14 nonobese and nondiabetic hypertensive subjects before and after treatment with benidipine or placebo, respectively, and 11 healthy control subjects. SSPG level was significantly higher in two hypertensive groups, indicating reduced insulin sensitivity than in controls. SSPG level significantly decreased after benidipine treatment, with a decrease of blood pressure. SSPG level and blood pressure did not change in the placebo group. As for oral glucose tolerance test, the area under the curve of insulin diminished significantly after benidipine treatment. SSPG level significantly correlated with intra-platelet Ca2+ concentrations in 9 hypertensive subjects. The long-acting Ca channel blocker benidipine has partially improved insulin resistance in essential hypertension, contributing to the prevention of atherosclerosis associated with insulin resistance.

Cilnidipine, the N- and L-type calcium channel antagonist, reduced on 24-h urinary catecholamines and C-peptide in hypertensive non-insulin-dependent diabetes mellitus

To evaluate the effects of cilnidipine (CNP), L- and N-type calcium channel blocker and nilvadipine (NVP) on 24-h urinary epinephrine (U-EP), norepinephrine (U-NE), dopamine (U-DA) and C-peptide (U-CPR) in patients associated with hypertension and non-insulin-dependent diabetes mellitus (HT-NIDDM), a randomized crossover study was performed with 35 HT-NIDDM patients. The patients were given CNP (10 mg/day) and NVP (8 mg/day), separately, for 4 weeks each. After CNP treatment, U-NE, U-DA and U-CPR levels were significantly reduced compared with pre-treatment levels: 160.4 +/- 12.7 to 111.7 +/- 8.9 microg/day (mean +/- S.E., P < 0.005); 934.8 +/- 163.4 to 590.3 +/- 33.4 microg/day (P < 0.05); 86.7 +/- 9.9 to 57.6 +/- 7.4 microg/day (P < 0.05), respectively. Although no significant differences were observed in U-EP, U-NE, U-DA and U-CPR levels by NVP treatment, U-NE, U-DA and U-CPR levels after CNP treatment were significantly lower than those after NVP treatment: 111.7 +/- 8.9 versus 155.0 +/- 13.7 microg/day (P < 0.02); 590.3 + 33.4 versus 822.2 +/- 104.3 microg/day (P < 0.05); 57.6 +/- 7.4 versus 80.6 +/- 8.1 microg/day (P < 0.05), respectively. In conclusion, it was demonstrated that CNP treatment significantly reduced U-NE, U-DA and U-CPR excretion compared with NVP treatment in HT-NIDDM patients.

Controlled study of the effect of angiotensin converting enzyme inhibition versus calcium-entry blockade on insulin sensitivity in overweight hypertensive patients: Trandolapril Italian Study (TRIS)

OBJECTIVE

The aim of this study was to evaluate the effect of trandolapril, an angiotensin converting enzyme inhibitor, on blood pressure, forearm blood flow and insulin sensitivity in comparison with nifedipine gastrointestinal therapeutic system.

PATIENTS AND METHODS

This is a multicentre, two-way parallel-group, open-label comparative study in 90 overweight hypertensive patients, who were randomly assigned to treatment for 8 weeks with either trandolapril or nifedipine. At baseline and after treatment, all patients underwent an oral glucose tolerance test, an evaluation of their metabolic profiles and a euglycaemic hyperinsulinaemic clamp test. In a subgroup of 18 patients, a forearm study was carried out.

RESULTS

Blood pressure fell by the second week of treatment and remained significantly reduced compared with baseline in both treatment groups. Plasma triglyceride levels were also significantly reduced after trandolapril therapy, but no significant changes occurred in the other metabolic parameters during treatment with either drug. During the euglycaemic hyperinsulinaemic clamp, whole-body glucose use was similar in the two treatment groups at baseline, and a moderate but statistically significant increase in insulin sensitivity was observed after trandolapril treatment (trandolapril: 5.0 +/- 0.2 versus 4.5 +/- 0.2 mg/kg per min; nifedipine: 4.1 +/- 0.3 versus 4.2 +/- 0.3 mg/kg per min; P < 0.05, versus baseline and trandolapril versus nifedipine treatment). Skeletal muscle glucose uptake was significantly higher after trandolapril than after nifedipine therapy (5.0 +/- 0.7 and 3.0 +/- 0.4 mg/min, respectively; P < 0.01). As forearm blood flow was similar in the two treatment groups at baseline and was unchanged after 8 weeks of therapy, skeletal muscle glucose extraction was significantly greater in the ACE inhibitor treated-group than in the nifedipine comparative group (trandolapril: baseline 21 +/- 2, treatment 24 +/- 3 mg/dl; nifedipine: baseline 18 +/- 3, treatment 16 +/- 2 mg/dl; P < 0.05, trandolapril versus nifedipine treatment).

CONCLUSIONS

During short-term treatment, ACE inhibition with trandolapril was able to moderately improve insulin sensitivity, in comparison with calcium blockade, and this effect appeared to be independent of the haemodynamic action of the drug.

Effect of the vasodilatory beta-blocker, nipradilol, and Ca-antagonist, barnidipine, on insulin sensitivity in patients with essential hypertension

OBJECTIVES

To assess the effects of a vasodilatory beta-adrenoceptor blocker, nipradilol, and a long-acting Ca channel blocker, barnidipine, on insulin sensitivity.

DESIGN

Insulin sensitivity was determined using a euglycemic hyperinsulinemic clamp technique before and after a 12-week treatment period in eighteen patients with essential hypertension.

RESULTS

Both drugs decreased blood pressure without affecting any serum parameters of glucose and lipid metabolism. Nipradilol significantly augmented glucose infusion rate (GIR) from 3.11+/-0.28 to 4.69+/-0.57mg/kg/min (p=0.027). Barnidipine also increased GIR from 3.91+/-0.43 to 5.29+/-0.43 mg/kg/min (p=0.028). Plasma norepinephrine concentrations significantly increased with barnidipine treatment, while nipradilol had no effect on plasma norepinephrine levels. No adverse events were reported during the study.

CONCLUSIONS

These results suggest that vasodilatory beta-blockers such as nipradilol and long-acting Ca channel blockers such as barnidipine may be useful in the treatment of insulin resistant hypertensive patients.

Absence of detectable regression of human hypertensive left ventricular hypertrophy following drug treatment for 1 year

1. The present study was designed to compare and contrast the effects of 1 year's treatment with angiotensin-converting enzyme inhibition (captopril 25-100 mg daily) and beta-blockade (atenolol 50-100 mg daily) on hypertensive cardiac structure and function as well as the other established cardiovascular risk factors of high blood pressure (BP), lipid profile and blood glucose. 2. This was a prospective randomized open drug trial with blinded end-point echocardiographic and cardiac Doppler assessment in 37 subjects who had primary essential hypertension and left ventricular hypertrophy of captopril (n = 20) versus atenolol (n = 17), adding hydrochlorothiazide if BP was not controlled by 1 month. Multiple time point measurements throughout the 1 year treatment period of the study were made of BP, echocardiographic parameters of cardiac structure and function, as well as lipid profile and blood glucose. 3. There were no significant between-group differences for captopril or atenolol with regard to BP (at baseline (mean +/- SD) 154.0/101.1 +/- 13.3/5.1 and 152.5/101.8 +/- 10.0/5.8 mmHg, respectively) which was normalized by 1 month (138.7/85.6 +/- 18.8/11.7 and 135.4/88.5 +/- 16.9/9.5 mmHg, respectively) in both treatment groups (both P < 0.01 vs baseline). Also, there were no between-group or within-group differences for any of the measures of left ventricular hypertrophy or systolic function throughout the 12 month treatment period; however, captopril alone significantly increased left ventricular early diastolic filling (P < 0.05 vs baseline) at most of the measured time points. Furthermore, there were no significant between- or within-group differences with regard to metabolic (lipids and glucose) profile over the 1 year treatment period of the present study. 4. Markers of cardiovascular risk, including BP, echocardiographic measures of left ventricular hypertrophy, lipid profile and blood glucose were not significantly different between therapies. Despite good BP control by 1 month, neither drug regimen regressed left ventricular hypertrophy. However, captopril significantly increased left ventricular early diastolic filling after 3 months of treatment.

Effects of 3-month nifedipine treatment on endocrine-metabolic parameters in patients with abdominal obesity and mild hypertension

It is widely accepted that abdominal obesity presents with exaggerated insulin secretion, insulin resistance and a trend toward glucose intolerance. Hypertension is frequently associated to abdominal obesity, and hyperinsulinism could play a role in its pathogenesis. Some studies reported that Ca-antagonists positively influence insulin sensitivity and glucose tolerance in obese patients with normal or elevated blood pressure. However, other studies reported worsening of metabolic balance during treatment with Ca-antagonists in hypertensive non-insulin-dependent diabetes mellitus (NIDDM) patients and in normal subjects. We studied 19 patients with abdominal obesity, mild hypertension and insulin resistance on balanced, mild hypocaloric diet (1400 Kcal), to verify the effects of the Ca-antagonist nifedipine on both basal and oral glucose tolerance test (OGTT)-induced glucose and insulin levels as well as on IGF-I basal and DHEA-S levels and fat mass (FM). To achieve this goal, 10 hypertensive obese subjects (HOB-NIFE, 3 males, 7 females, mean age +/- SD 44.6 +/- 1.7 yr; body mass index (BMI) 37.1 +/- 2.5 Kg/m2, WHR 0.95 +/- 0.02) received 3-month treatment with nifedipine (Adalat Crono 30 Bayer, 1 tab daily) while other 9 hypertensive obese (HOB, 3 males, 6 females, 42 +/- 2.4 yr, BMI 35.8 +/- 1.8 Kg/m2, WHR 0.91 +/- 0.03) were studied during diet only. The same parameters were studied also in 8 normotensive obese patients (OB: 3 males, 5 females, 48.1 +/- 2.1 yr, BMI 35.8 +/- 2.4 Kg/m2, WHR 0.90 +/- 0.03) on the same balanced hypocaloric diet. Basal systolic (SBP) and diastolic (DBP) blood pressure levels in HOB-NIFE and HOB were similar. At baseline, all groups had similar basal and OGTT-induced glucose, insulin and glucose insulin ratio (GIR) levels as well as IGF-I and DHEA-S levels. After 3 months BMI fell to the same extent in all groups (p < 0.05 vs baseline) while WHR and FFM/FM ratio did not change. SBP and DBP decreased HOB-NIFE (p < 0.02) but also during diet alone in both HOB and OB, though to a lesser extent (p < 0.05). Both basal and OGTT-stimulated glucose and insulin levels as well as IGF-I and DHEA-S levels were not modified in HOB-NIFE as well as in HOB and OB. In conclusion, our data indicate that nifedipine treatment does not modify glucose tolerance as well as insulin secretion and sensitivity, IGF-I and DHEA-S levels in hypertensive abdominal obese patients. Thus, nifedipine treatment has no detrimental effects on endocrine-metabolic balance in hypertensive obese patients.

Effects of calcium antagonists on insulin sensitivity and other metabolic parameters

The antihypertensive efficacy of calcium antagonists appears to be comparable to that of oral diuretics when used as monotherapy. Peripheral vascular dilation appears to be the principal mechanism of the long-term blood pressure-lowering effects of calcium antagonists. The calcium antagonists appear to have beneficial effects with respect to maintenance of renal blood flow and glomerular filtration rate. Metabolic abnormalities associated with diuretic and beta-blocker antihypertensive therapy, such as hypokalemia, hypercalcemia, hyperuricemia, lipid changes, and hyperglycemia, are generally not observed with calcium antagonists.

Calcium channel blockers and hypertension: evolving perspective--1996

In recent years, calcium channel blockers (CCBs) have been used extensively in the United States and elsewhere as antihypertensive agents, and their availability has been an important advance in the management of hypertension. As antihypertensive agents, the CCBs thus appear considerably more versatile than most previous vasodilators. The available studies indicate that CCBs are metabolically neutral and do not exacerbate dyslipidemia or impair glucose tolerance. In contrast to diuretics and beta-blockers, CCBs do not appear to alter insulin sensitivity. The CCBs also differ from previous vasodilators because of their favorable accompanying effects on the heart and kidney. Despite the attributes of CCBs enumerated earlier, a number of recent retrospective analyses by Psaty et al. (JAMA 1995;274:620-625) have suggested that CCBs may be detrimental and may promote adverse cardiovascular events. I have recently reviewed the results of Psaty's meta-analysis and report (Arch Intern Med 1995;155: 2150-2156). I have emphasized that it is the rate of drug delivery into the systemic circulation that produces profound effects on the hemodynamic and neurohumoral responses to a dihydropyridine CCB drug. During chronic treatment with dihydropyridines, major fluctuations in blood pressure (rapid onset and offset of antihypertensive effects) during the dosing interval may persist for drugs and formulations that are short acting. In contrast, slow-release formulations of otherwise rapidly absorbed dihydropyridines achieve a more gradual and sustained antihypertensive effect. It is probable that newer CCB formulations that do not provoke intermittent sympathetic activation and do not evoke a cardioacceleratory response would not be expected to promote adverse cardiovascular events.

Considerations in the treatment of insulin resistance and related disorders with a new sympatholytic agent

BACKGROUND

Prospective studies have documented the importance of blood glucose control in diabetic patients for risks for cardiovascular diseases. At age 70 years, more than 30% of people are hypertensive and among these about one-third have diabetes or impaired glucose tolerance. It is urgent to treat hypertension in these patients with drugs that do not further impair glucose control.

DRUG STUDIES

Prospective, randomized studies with antihypertensive drugs have demonstrated differences between different classes of drugs regarding effects on insulin sensitivity. Thus, treatment with beta-blockers or diuretics is associated with impaired insulin sensitivity, whereas most modern calcium channel blockers and angiotensin converting enzyme inhibitors are neutral. The most pronounced improvements have been obtained with alpha1-blockers. A new class of drugs, imidazoline I1-imidazoline receptor agonists, may be of interest in this context. Moxonidine, a drug in this class, inhibits sympathetic outflow and causes vasodilation. This effect together with other characteristics may lead to improved insulin resistance and glucose control.

CONCLUSIONS

In populations at high risk for diabetes, it may be justified to select drugs that improve insulin sensitivity when treating insulin-resistant individuals for hypertension.

Effect of nifedipine, captopril and prazosin on secretory function of pancreatic beta-cells in hypertensive patients with type-2 (non-insulin-dependent) diabetes and in hypertensive non-diabetics

The aim of our study was to compare the effect of captopril--the angiotensin-converting enzyme inhibitor, nifedipine--the calcium antagonist, and prazosin--the alpha blocker, on the secretory function of pancreatic beta-cells in hypertensive patients with NIDDM and with normal glucose tolerance. The effect of a 2-week treatment with nifedipine, captopril and prazosin upon glycaemia, serum insulin (IRI) and C-peptide (CP) following oral and intravenous glucose load were investigated in three groups, each including 10 non-diabetic patients with essential hypertension (h) and 10 hypertensive type 2 (non-insulin-dependent) diabetics (h + d), aged 32-63 years. Nifedipine produced increase in glycaemia in the oral test in both groups. In the (h) group, but not in the (h + d) group, the drug caused reduction of the glucose-dependent increases in serum IRI and CP, more marked with respect to CP, as expressed by the decrease in the molar serum CP/IRI ratio. These results indicate that in non-diabetic patients, nifedipine reduces the early response of beta-cells to glucose, but this effect is partly compensated by a decreased insulin uptake by the liver. In patients with type 2 diabetes, this phenomenon does not become manifest because of absence or reduction in the early glucose-dependent insulin release. After captopril, lower values of glycaemia and serum IRI and CP were observed in both groups suggesting an improvement of insulin sensitivity. In conclusion, nifedipine has a small influence, and captopril and prazosin are devoided of any influence on the secretory function of pancreatic beta-cells. These drugs may be recommended for the treatment of hypertension in patients with type 2 (non-insulin-dependent) diabetes.

Effects of antihypertensive drugs on coronary artery disease risk: a meta-analysis

1. The effects of antihypertensive drugs on lipids may also influence their effect on coronary artery disease (CAD). However, the clinical significance of these effects and the extent to which they persist during long-term therapy is uncertain. 2. We performed a meta-analysis on 23 randomized trials published between 1988 and 1994 that compared the effects of atenolol, celiprolol (a beta-blocker with beta 2-adrenoceptor intrinsic sympathomimetic activity), enalapril, nifedipine and doxazosin on plasma cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglycerides and blood pressure (BP). 3. Predicted changes in CAD risk were calculated by incorporating the results for these parameters into the Framingham equations. 4. While there were no differences in antihypertensive efficacy between the drugs, atenolol significantly (P < 0.05) reduced HDL-C and increased total cholesterol, LDL-C and triglycerides compared with celiprolol, enalapril, doxazosin and nifedipine. 5. The magnitude of the effects on lipids was not significantly influenced by the duration of therapy (up to 3 years for atenolol and doxazosin and up to 2 years for celiprolol). 6. The improvement in Framingham equation point scores (systolic BP formula) was significantly (P < 0.05) less for atenolol (-0.54; confidence intervals (CI) -0.29-(-0.78)) than for celiprolol (-1.69; CI -0.68-2.70), doxazosin (-1.67; CI -1.11-(-2.23)), enalapril (-1.43; CI 0.23-(-3.07)) and nifedipine (-1.91; CI -1.22-(-2.59)). Similar results were obtained for the Framingham diastolic BP formula. 7. These results suggest that the adverse effects of atenolol ]on plasma lipids do not improve with prolonged therapy and are theoretically great enough to reduce its efficacy in reducing CAD by approximately two thirds compared with antihypertensive drugs that do not adversely affect plasma lipids. However it must be emphasized that these are theoretical effects. In order to determine the actual differences between these drugs on CAD end points, studies using these end points are required.

Effects of a calcium channel blocker, manidipine, on insulin sensitivity in essential hypertensives

This study was designed to investigate the effects of the calcium channel blocker manidipine on insulin-dependent glucose uptake (insulin sensitivity) and insulin action to renal sodium handling and pressor systems in essential hypertensive (EHT). Seven EHT were hospitalized and a 2-h euglycemic hyperinsulinemic glucose clamp was performed in a fasting condition before and after 2 weeks administration of manidipine (20 mg/day). Insulin sensitivity was evaluated as M-value calculated from the infusion rate of glucose. Manidipine administration decreased mean blood pressure and increased M-value significantly in EHT. Before the manidipine treatment, hyperinsulinemia during the clamp induced a decrease of urinary sodium excretion and increases of plasma norepinephrine and plasma renin activity in EHT. After manidipine treatment, however, hyperinsulinemia induced natriuresis and did not augment the pressor systems activity. Thus, the calcium channel blocker improved insulin resistance as assessed by glucose clamp technique in EHT. Suppression of augmented renal sodium reabsorption and pressor system activities of insulin may be connected with the hypotensive mechanisms and the natriuresis caused by calcium channel blockers.

Improvement of insulin sensitivity for glucose metabolism with the long-acting Ca-channel blocker amlodipine in essential hypertensive subjects

To clarify whether the long-acting calcium-channel blocker amlodipine restores insulin insensitivity in essential hypertension, insulin sensitivity tests were performed at the physiological steady-state insulin level (45 to 55 microU/mL) before and after amlodipine (2.5 to 7.5 mg/d) administration for 2 to 4 months in borderline and mild essential hypertensive subjects. Instead of somatostatin, Sandostatin (Sandoz, Basel, Switzerland) was used for the determination of steady-state plasma glucose (SSPG) in the same way as previously described. SSPG, which was initially high (212.9 +/- 18.0 mg/dL, mean +/- SE), was significantly reduced to 169.8 +/- 14.7 after amlodipine treatment. Responses of ketone bodies during the test at 30 minutes, which reflect the insulin effect on lipolysis in adipose tissue and hepatic fatty acid oxidation, also improved after amlodipine treatment. Norepinephrine, noted to be mildly elevated after amlodipine treatment, decreased during the sensitivity test at 2 hours probably due to the sedative effect, without any change in the fractional extraction of Na. This indicates that the physiological level of insulin does not activate sympathetic nerve activity or stimulate Na reabsorption. The long-acting calcium-channel blocker amlodipine has significantly improved the initially decreased insulin sensitivity for glucose metabolism at least partially in borderline or mild essential hypertension.

Nicardipine may impair glucose metabolism in hypertensive diabetic patients

The respective effects of 6 month's administration of beta-blockers (atenolol, metoprolol, carteolol and arotinolol), calcium-channel blockers (nicardipine, diltiazem) and angiotensin converting enzyme inhibitor (enalapril) on hemoglobin A1c (HbA1c) levels were evaluated in hypertensive patients with non-insulin-dependent diabetes mellitus (NIDDM), using a retrospective method. NIDDM patients with stable HbA1c and body weight were selected for this study. The following results were obtained. (1) The administration of nicardipine or beta-blockers significantly elevated HbA1c levels. (2) The administration of diltiazem or enalapril did not have any influence on HbA1c levels. These findings suggest that not only beta-blocker but nicardipine (dihydropyridine type calcium-channel blocker) may cause deterioration in glucose metabolism in NIDDM patients.

Metabolic risk factors for atherosclerosis in heart transplant recipients

Development of coronary artery disease (CAD) in the cardiac allograft limits long-term survival after heart transplantation. Previous studies, focusing on lipoprotein metabolism, have paid little attention to changes in glucose and insulin metabolism that increase the risk of CAD in these patients. To address this issue, plasma glucose and insulin responses to an oral glucose load and lipid and lipoprotein concentrations were measured in male normal volunteers (n = 40) and cardiac transplant recipients with pretransplant diagnoses of either idiopathic cardiomyopathy (n = 24) or ischemic heart disease (n = 28), matched for age and body mass index. Patients with a pretransplant diagnosis of ischemic heart disease had higher plasma glucose and insulin concentrations in response to oral glucose as well as higher fasting plasma triglyceride, cholesterol, and low-density lipoprotein cholesterol concentrations than did the control group (p < 0.005 to p < 0.001). In addition, high-density lipoprotein cholesterol concentrations were lower and the ratio of cholesterol to high-density lipoprotein cholesterol higher than control values in those with a pretransplant diagnosis of ischemic heart disease (p < 0.001). Values for almost all variables were intermediate in patients with a pretransplant diagnosis of idiopathic cardiomyopathy and in most instances were significantly different from both. Thus, male cardiac transplant recipients are dyslipidemic, relatively glucose intolerant, and hyperinsulinemic compared to normal volunteers. These changes, observed in patients with a pretransplant diagnosis of either ischemic heart disease or idiopathic cardiomyopathy, emphasize the important role of immunosuppression in the development of metabolic risk factors for CAD in these individuals.

Metabolic effects of isradipine as monotherapy or in combination with pindolol during long-term antihypertensive treatment

OBJECTIVES

To evaluate the effects of isradipine alone and in combination with pindolol on glucose and lipid metabolism during long-term antihypertensive therapy.

DESIGN

Open long-term study with parallel groups.

SETTING

Kungsgärdet Geriatric Hospital, Uppsala, a tertiary referral hospital.

SUBJECTS

Twenty-six untreated hypertensive subjects.

INTERVENTIONS

After 4 weeks on placebo, isradipine was titrated up to 10 mg daily to achieve appropriate blood pressure control (n = 11). If this failed, 5-10 mg pindolol was added. The treatments were continued for 2 years.

MAIN OUTCOME MEASURES

Blood pressure, lipoprotein measurements, intravenous glucose tolerance test, hyperinsulinaemic euglycaemic clamp, HbA1c, body weight.

RESULTS

Treatment with isradipine alone caused a sustained reduction in blood pressure (-22/-10 mm Hg, P < 0.01), but an increase in body weight (+2.2 kg, P < 0.05) and HbA1c (+1.5%; P < 0.001) were also noted. Addition of pindolol resulted in a similar degree of blood pressure reduction and weight gain, whilst HbA1c was less affected (+1.0%; P < 0.05, compared to isradipine alone). Insulin sensitivity became impaired in both groups (-1.2 to -1.5 mg kg-1 min-1; P < 0.01 for M-value at hyperinsulinaemic clamp) but after adjustment for the change in body weight the impairment was only significant (P < 0.01) in the group with combined treatment. The combined treatment also resulted in an increase in very-low-density-lipoprotein (VLDL) triglycerides (+ 0.37 mmol L-1; P < 0.05).

CONCLUSIONS

The hypotensive effect of isradipine was sustained during long-term use but was associated with weight gain and an impaired glucose control. When isradipine was combined with pindolol there was also a reduction in insulin sensitivity and an increase in VLDL triglycerides, possibly as effects of the beta-adrenergic blockade.

Nitrendipine improves glucose tolerance and deoxyglucose uptake in hypertensive rats

We assessed the effect of the vasodilating calcium channel blocker nitrendipine on glucose tolerance in young spontaneously hypertensive rats (SHR) (n = 15). The nitrendipine group received 1 g/kg chow for 3 weeks. Untreated SHR (n = 14) served as controls. At 3 weeks body weight was comparable, whereas systolic blood pressure was 157 +/- 9 mm Hg in nitrendipine-treated rats versus 191 +/- 10 mm Hg in controls (mean +/- SD, P < .00001). Fasting glucose was 6.8 +/- 2.7 mmol/L in nitrendipine-treated versus 8.9 +/- 1.5 mmol/L in control rats (P < .03). An intravenous glucose tolerance test (300 mg/kg) showed plasma glucose levels at 2, 5, 15, and 30 minutes to be significantly lower in the nitrendipine-treated group versus controls (two-way ANOVA, P < .03). Glucose utilization was estimated by the uptake of [3H]deoxyglucose after its intravenous administration (2 microCi/100 g body wt) to instrumented awake animals. Heart and striated muscle uptake was, respectively, 7983 +/- 5812 and 951 +/- 731 cpm.microL/g.min in the nitrendipine-treated group versus 3532 +/- 2316 and 424 +/- 201 cpm.microL/g.min in controls (P < .02 and P < .04, respectively). [3H]Deoxyglucose plasma half-life and fasting and post-glucose load insulin levels were comparable in the two groups. The results show that nitrendipine improves glucose tolerance by increasing muscle glucose uptake. We suggest that glucose tolerance in SHR is influenced by muscle blood flow and can be improved by vasodilation.

The effect of angiotensin II receptor blockade on insulin sensitivity and sympathetic nervous system activity in primary hypertension

The objective of this study was to investigate the effect of Losartan (NK-954, DuP-753), a new selective angiotensin II receptor antagonist, on insulin sensitivity and sympathetic nervous system activity in patients with severe primary hypertension. Five patients with a record of diastolic blood pressure (DBP) > or = 115 mmHg, currently either untreated or with DBP > 95 mmHg on antihypertensive treatment, were examined in an open study with the euglycemic glucose clamp examination before and after being treated with Losartan for an average of 6 weeks. The glucose disposal rate increased from 6.2 +/- 2.6 to 7.9 +/- 2.6 mg/kg x min (27%, p < 0.05) during treatment with Losartan. The insulin sensitivity index (glucose disposal rate divided by mean insulin concentration during clamp) increased from 7.7 +/- 4.5 to 10.1 +/- 4.1 arbitrary units (30%, p < 0.05). Plasma noradrenaline decreased from 1.87 +/- 0.53 to 1.11 +/- 0.13 nmol/l (40%, p < 0.05), while plasma adrenaline was unchanged (0.23 +/- 0.10 vs. 0.22 +/- 0.11 nmol/l, n.s.). Mean blood pressure decreased from 132 +/- 10 to 119 +/- 13 mmHg (p < 0.05) and heart rate was unchanged during treatment with Losartan. Thus, antihypertensive treatment with the new selective angiotensin II receptor antagonist Losartan seems to improve insulin sensitivity. A decrease in plasma noradrenaline on Losartan suggests a sympathicolytic effect which together with vasodilation may explain the fall in blood pressure and the improvement in insulin sensitivity.

Altered body composition and fuel metabolism in stable kidney transplant patients on immuno-suppressive monotherapy with cyclosporine A

Glucocorticoid associated altered body fat distribution and muscle wasting are well known following kidney grafting. Whether an immunosuppressive regimen after glucocorticoid withdrawal (i.e. monotherapy with cyclosporine A (CsA)) is associated with normalization of altered body fat distribution and muscle mass remains to be determined. Therefore 18 renal transplant patients (nine males and nine females, 64 +/- 5 (mean +/- SEM) months since transplantation; CsA-monotherapy: 38 +/- 7 months) and 18 age, sex and body mass index matched healthy volunteers were investigated using indirect calorimetry and dual energy X-ray absorptiometry. Lean body mass (LBM) was decreased in patients mostly due to loss of striated muscle in the legs (P < 0.01). Compared to healthy controls, fat mass was increased in head and trunk (P < 0.01) and similar in extremities. Resting energy expenditure expressed per kg LBM was increased by more than 10% (P < 0.05) in patients vs. controls. Plasma insulin and glucose concentrations, total serum cholesterol (C), triglyceride levels and the ratio of LDL-C to HDL-C were all elevated (P < 0.01) in patients as compared with controls. In summary, renal transplant patients on immunosuppressive monotherapy with CsA demonstrate decreased muscle mass despite discontinuation of prednisone therapy. The increased upper body fat might account, at least in part, for peripheral hyperinsulinaemia and dyslipidaemia observed in kidney transplant patients even years after successful transplantation.

Effect of nicardipine treatment on carbohydrate and lipoprotein metabolism in patients with hypertension

This study evaluated the effect of nicardipine, calcium channel blocker, monotherapy on blood pressure and metabolic changes. Various aspect of carbohydrate and lipoprotein metabolism were studied before and after 12 weeks of nicardipine treatment in 23 patients with mild to moderate essential hypertension. Nicardipine was well tolerated and induced a significant decrease (p < 0.001) in both systolic and diastolic blood pressure without any changes in heart rate. Plasma levels of fasting glucose, insulin, C-peptide and hemoglobin A1c, hepatic extraction of insulin were similar following nicardipine treatment. Plasma glucose and insulin responses to an oral glucose challenge did not change in association with nicardipine therapy. Although high density lipoprotein (HDL) cholesterol concentration increased slightly, it did not reach statistical significance. Total cholesterol and low density lipoprotein (LDL) cholesterol levels also increased insignificantly. LDL triglyceride and very low density lipoprotein (VLDL) triglyceride concentrations were higher marginally, which resulted in slightly but insignificantly increase in total triglyceride concentration in association with nicardipine monotherapy for 12 weeks. In conclusion, treatment of patients with mild to moderate hypertension with nicardipine led to lower blood pressure effectively while had no significant influence on carbohydrate and lipoprotein metabolism.

Relationships between blood pressure and lipids in childhood

This review has discussed the potential interrelationships of elevated blood pressure and lipid abnormalities. Most of the data for this review have been collected in adults, but physiologic and genetic effects may have expression in childhood. Clustering of cardiac risk factors may be mediated by increased levels of insulin. These increased levels of insulin may be genetically determined or may be related to obesity. Recognition of the multiple risk factor phenotype is important, because individuals with multiple risk may have a much higher risk of future coronary events than do individuals with single risk factors. Medical therapy of individuals with multiple risk should be more aggressive than for individuals with single risk factors. Physicians should be cautious about therapy in the pediatric setting because of possible interaction between therapeutic agents and risk factors, however.

The role of the renin-angiotensin system in insulin sensitivity in normotensive subjects

Nonobese patients with essential hypertension have been reported to be insulin resistant. Because blockade of the renin-angiotensin system has been demonstrated to improve insulin sensitivity in hypertensive patients, the authors evaluated the effects of angiotensin-II administration and of angiotensin-converting enzyme inhibition with enalapril on insulin-mediated glucose uptake in normotensive men. The results showed no change in insulin sensitivity with either 0.3 ng/kg/min or 1 ng/kg/min angiotensin-II administration or with enalapril therapy. The authors conclude that neither physiologic amounts of angiotensin-II nor converting enzyme inhibition alter insulin sensitivity in normotensive men.

Individualised selection of antihypertensive therapy

Theoretically, it should be possible to match the requirements of individual patients with the pharmacological and clinical properties of the large number of antihypertensive drugs now available. The concept of automatic sequential stepped-care therapy is now largely outdated, but therapy of clinically important hypertension must be initiated with one agent. Diuretics remain a first-line option in the elderly and in Black patients, as do calcium antagonists. Outcome trials are available only for the elderly, and in these the benefits of initial diuretic therapy are well documented. Nonetheless, diuretics may often need to be co-prescribed with a beta-blocker or an adrenergic modifier such as methyldopa. beta-Blockers are preferred in patients with ischaemic heart disease or enhanced adrenergic drive, while alpha-blockers are preferred in patients with blood lipid abnormalities or prostatic problems. Calcium antagonists or angiotensin converting enzyme (ACE) inhibitors are being increasingly used as initial therapy when quality of life is important and metabolic neutrality is required. Calcium antagonists are more likely to be effective first-line therapy than ACE inhibitors in patients with a high salt intake, in patients with Raynaud's disease, when angina pectoris is present, and in Black patients. ACE inhibitors are preferred for combination with diuretic agents, and in the presence of congestive heart failure or low salt intake. Experimentally, both calcium antagonists and ACE inhibitors can prevent ischaemic ventricular fibrillation and atheroma. Combination therapy between these 2 drug classes is gaining increasing acceptance because of these theoretical advantages.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin resistance and cardiovascular drugs

Under certain circumstances the effect of insulin to promote glucose uptake in peripheral tissues is reduced because of a resistance to insulin action. This insulin resistance and the resulting hyperinsulinaemia are now recognised as common background factors that may be responsible for hypertension, hyperlipidaemia, decreased thrombolysis and also impaired glucose tolerance and diabetes. Hyperinsulinaemia has also been identified as an independent risk factor for coronary heart disease and promotes smooth muscle cell growth and plaque formation. A series of studies have now demonstrated that treatment with selective beta-blockers as well as thiazide diuretics impair insulin sensitivity by 15-30% and causes a compensatory increase in insulin concentrations. Furthermore, lipoprotein concentrations are affected in an unfavourable way. This is in contrast to the drugs belonging to ACE-inhibitors, calcium-channel blockers and alpha 1-blocker classes that are either neutral or may have the opposite effects in these respects.

Insulin resistance and hypertension

The author has reviewed the development of the concept that insulin resistance is related not only to the hypertensive state but potentially to the initiation and maintenance of high blood pressure. Potential sequelae of insulin resistance and hyperinsulinemia, as they apply to atherogenesis, are also discussed. The impact of present antihypertensive pharmacologic therapy on insulin resistance is addressed, as are future directions in pharmacologic and nonpharmacologic management of hypertension. In addition, the author speculates on possible mechanisms leading to insulin resistance in hypertension.