The ACE-inhibitor lisinopril affects plasma insulin levels but not fibrinolytic parameters

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Angiotensin-converting enzyme inhibition alters the fibrinolytic response to cardiopulmonary bypass

BACKGROUND

Increased plasminogen activator inhibitor-1 (PAI-1) concentrations after coronary artery bypass grafting (CABG) are associated with increased risk of vein graft occlusion. Because angiotensin II stimulates PAI-1 expression, we tested the hypothesis that preoperative angiotensin-converting enzyme (ACE) inhibition decreases PAI-1 expression after CABG.

METHODS AND RESULTS

We measured the effects of cardiopulmonary bypass (CPB) on PAI-1 antigen and tissue-type plasminogen activator (tPA) antigen and activity in 31 patients taking an ACE inhibitor (ACEI) who were randomized to continue ACEI until the morning of surgery (ACEI group, n=19) or to discontinue it 48 hours before surgery (No-ACEI group, n=12). Arterial blood samples were taken at baseline before CPB, twice during CPB, after separation from CPB, and on postoperative day 1 (POD1). CPB caused an early decrease in PAI-1 antigen, followed by an increase in PAI-1 antigen on POD1 (P<0.001 for effect of time). ACE inhibition attenuated the increase in PAI-1 antigen such that both PAI-1 antigen on POD1 (P=0.013) and the change in PAI-1 antigen from baseline to POD1 (P=0.009) were higher in the No-ACEI group (from 17.0+/-5.0 to 48.7+/-8.8 ng/mL) versus the ACEI group (from 19.9+/-3.4 to 33.1+/-6.2 ng/mL). There was no significant difference between the 2 groups in intraoperative tPA activity (P=0.259); however, the increase in tPA activity was significantly greater in the ACEI group than in the No-ACEI group (P=0.030).

CONCLUSIONS

Preoperative ACEI attenuates the increase in PAI-1 after CABG, suggesting a role for ACE inhibition in reducing the risk of acute graft thrombosis.

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.

Tissue availability of insulin-like growth factor I is inversely related to insulin resistance in essential hypertension: effects of angiotensin converting enzyme inhibition

BACKGROUND

The insulin-like growth factor I possesses biologic actions that resemble those of insulin. Tissue access of the factor depends on the distribution of the circulating bound factor between its binding protein 3 that remains within the intravascular space and its binding protein I that is able to cross the endothelium. Preliminary results have shown that tissue availability of insulin-like growth factor I is a determinant of glucose regulation in essential hypertension

OBJECTIVE

To investigate whether the tissue availability of circulating insulin-like growth factor I in patients with essential hypertension is related to insulin resistance and whether chronic angiotensin converting enzyme inhibition influences tissue availability of the factor and insulin resistance in these patients.

DESIGN AND METHODS

We studied 29 patients with essential hypertension and 20 age-matched and sex-matched normotensive subjects. The measurements were repeated for 25 patients after 12 months of treatment with lisinopril. Tissue availability of circulating insulin-like growth factor I was assessed by analyzing its distribution between its binding proteins 3 and 1. An insulin resistance index was estimated using the homeostasis model analysis of fasting insulin-glucose interactions. Levels of serum insulin-like growth factor I binding proteins 3 and 1, plasma insulin-like growth factor I, and insulin were determined by specific radioimmunoassays.

RESULTS

Baseline insulin resistance index was significantly higher in the hypertensive patients than it was in the normotensive controls. With the upper 100% confidence limit of the normotensive population as the cutoff point, a subgroup of 12 hypertensives had an abnormally high insulin resistance index. Compared with patients with normal insulin resistance indexes, patients with greater than normal indexes were characterized by lower binding protein 1 levels, similar binding protein 3 levels, lower binding protein 1 : binding protein 3 ratio and similar insulin-like growth factor I levels. The serum binding protein 1 level and the binding protein 1 : binding protein 3 ratio were inversely correlated to the insulin resistance index for the whole group of hypertensives. After treatment with lisinopril hypertensive patients with higher than normal insulin resistance indexes at baseline exhibited normalization of this parameter and significant increases of binding protein 1 levels and binding protein 1 : binding protein 3 ratio, with no significant changes in insulin-like growth factor I levels. These parameters remained unchanged for the remaining patients.

CONCLUSIONS

These results suggest that tissue availability of circulating insulin-like growth factor I is a determinant of insulin sensitivity in patients with essential hypertension. Whereas the patients with normal insulin sensitivity exhibit greater than normal tissue access of circulating insulin-like growth factor I, patients with insulin resistance present normal tissue access of the factor. Our findings suggest that the ability of angiotensin converting enzyme inhibitors to restore insulin sensitivity in essential hypertensives may be related to their ability to facilitate the tissue availability of circulating insulin-like growth factor I.

Lisinopril. A review of its pharmacology and use in the management of the complications of diabetes mellitus

Lisinopril, like other ACE inhibitors, lowers blood pressure and preserves renal function in hypertensive patients with non-insulin-dependent or insulin-dependent diabetes mellitus (NIDDM or IDDM) and early or overt nephropathy, without adversely affecting glycaemic control or lipid profiles. On available evidence, renoprotective effects appear to be greater with lisinopril than with comparator calcium channel blockers, diuretics and beta-blockers, despite similar antihypertensive efficacy. As shown by the EUCLID (EUrodiab Controlled trial of Lisinopril in Insulin-Dependent Diabetes) trial, lisinopril is also renoprotective in normotensive patients with IDDM and microalbuminuria. The effect in normotensive patients with normoalbuminuria was smaller than in those with microalbuminuria, and no conclusions can yet be made about its use in patients with normoalbuminuria. In complications other than nephropathy, lisinopril has shown some benefit. Progression to retinopathy was slowed during 2 years' lisinopril therapy in the EUCLID study. Although not yet fully published, these results provide the most convincing evidence to date for an effect of an ACE inhibitor in retinopathy. The drug may also improve neurological function, but this finding is preliminary. Lastly, post hoc analysis of the GISSI-3 trial indicates that lisinopril reduces 6-week mortality rates in diabetic patients when begun as early treatment after an acute myocardial infarction. The tolerability profile of lisinopril is typical of ACE inhibitors and appears to be similar in diabetic and nondiabetic individuals. Hypoglycaemia has occurred at a similar frequency with lisinopril and placebo, as shown in the EUCLID trial. In addition, the GISSI-3 study indicates that the incidence of persistent hypotension and renal dysfunction is increased with lisinopril in general, but the presence of diabetes does not appear to confer additional risk of these events in diabetic patients with acute myocardial infarction receiving lisinopril. In summary, lisinopril lowers blood pressure and produces a renoprotective effect in patients with IDDM and NIDDM without detriment to glycaemic control or lipid profiles. Like other ACE inhibitors, lisinopril should thus be viewed as a first-line agent for reducing blood pressure and preventing or attenuating nephropathy in hypertensive diabetic patients with IDDM or NIDDM and microalbuminuria or overt renal disease. The EUCLID study, using lisinopril, provides new data supporting an additional place in managing normotensive patients with microalbuminuria and IDDM. These findings, together with some evidence for an effect of lisinopril in delaying progression of retinopathy and in reducing mortality, suggest a broader role for the drug in managing diabetic vascular complications.

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.